Actron CP7665 User Manual

OPERATING

INSTRUCTIONS

Index

Safety Precautions .................................. 2

Vehicle Service Information .................... 3

Visual Inspection ..................................... 3

Electrical Specifications ........................ 32

Warranty ................................................ 96

1. Multimeter Basic Functions

Functions and Display Definitions ...... 4

Setting the Range ............................... 6

Battery and Fuse Replacement.......... 7

Measuring DC Voltage........................ 8

Measuring AC Voltage........................ 8

Measuring Resistance ........................ 9

Measuring DC Current......................10

Testing Diodes .................................. 11

Testing B at te ri es ...............................1 2

2. Automotive Testing with the CP7665

General Testing................................. 13

-Testing Fuses ................................. 13

-Testing Switches.............................13

-Testing Solenoids and Relays........ 14

CP7665

Starting / Charging System Testing .15

- No Load Battery Test ......................15

- Engine Off Battery Current Draw ...16

-

Cranking Voltage/Battery Load Test .

- Voltage Drops .................................18

- Charging System Voltage Test ...... 19

Ignition System Testing ....................21

- Ign it io n Co il T es ti n g ........................21

- Ignition System Wires .....................23

- Magnetic Pick-Up Coils ..................24

- Reluctance Sensors........................24

Fuel System Testing ......................... 25

-

Measuring Fuel Injector Resistance..

Testing Engine Sensors.................... 27

- Oxygen (O

- Temperature Type Sensors ............29

- Position Type Sensors –
Throttle and EGR Valve Position,

Vane Air Flow.................................. 30

Instrucciones en español .... 33

Instructions en français ....... 65

1

) Type Sensors............. 27

2

17

25

SAFETY GUIDELINES

TO PREVENT ACCIDENTS THAT COULD RESULT IN SERIOUS

INJURY AND/OR DAMAGE TO YOUR VEHICLE OR TEST

EQUIPMENT, CAREFULLY FOLLOW THESE SAFETY RULES AND

TEST PROCEDURES

• Always wear approved eye
protection.

• Always operate the vehicle in a
well ventilated area. Do not inhale
exhaust gases – they are very
poisonous!

• Always keep yourself, tools and
test equipment away from all
moving or hot engine parts.

• Always make sure the vehicle is in

park (Automatic transmission) or
neutral (manual transmission) and
that the parking brake is firmly
set. Block the drive wheels.

• Never lay tools on vehicle battery.
You may short the terminals
together causing harm to yourself,
the tools or the battery.

• Never smoke or have open flames
near vehicle. Vapors from gasoline

and charging battery are highly
flammable and explosive.

• Never leave vehicle unattended
while running tests.

• Always keep a fire extinguisher
suitable for gasoline/electrical/
chemical fires handy.

• Always use extreme caution when
working around the ignition coil,
distributor cap, ignition wires, and
spark plugs. These components
contain High Voltage when the
engine is running.

• Always turn ignition key OFF
when connecting or disconnect­ing electrical components, unless
otherwise instructed.

• Always follow vehicle
manufacturer’s warnings,
cautions and service procedures.

CAUTION:

Some vehicles are equipped with safety air bags. You

service manual cautions when working around the air bag components or
wiring. If the cautions are not followed, the air bag may open up unexpect­edly, resulting in personal injury. Note that the air bag can still open up
several minutes after the ignition key is off (or even if the vehicle battery is
disconnected) because of a special energy reserve module.

must

follow vehicle

All information, illustrations and specifications contained in this manual are based on the latest
information available from industry sources at the time of publication. No warranty (expressed or
implied) can be made for its accuracy or completeness, nor is any responsibility assumed by Actron
Manufacturing Co. or anyone connected with it for loss or damages suffered through reliance on
any information contained in this manual or misuse of accompanying product. Actron Manufactur­ing Co. reserves the right to make changes at any time to this manual or accompanying product
without obligation to notify any person or organization of such changes.

2

Vehicle Service Manual – Sources For Service
Information

The following is a list of sources to obtain vehicle service information for your
specific vehicle.

• Contact your local Automotive Dealership Parts Department.

• Contact local retail auto parts stores for aftermarket vehicle service

information.

• Contact your local library. Libraries often allow you to check-out automo­tive service manuals.

Do a Thorough Visual Inspection

Do a thorough visual and “hands-on” underhood inspection before
starting any diagnostic procedure! You can find the cause of many
problems by just looking, thereby saving yourself a lot of time.

• Has the vehicle been serviced
recently? Sometimes things get
reconnected in the wrong place,
or not at all.

• Don’t take shortcuts. Inspect
hoses and wiring which may be
difficult to see due to location.

• Inspect the air cleaner and
ductwork for defects.

• Check sensors and actuators for
damage.

• Inspect ignition wires for:

- Damaged terminals.

- Split or cracked spark plug

boots

- Splits, cuts or breaks in the

ignition wires and insulation.

• Inspect all vacuum hoses for:

- Correct routing. Refer to ve-

hicle service manual, or Ve-

hicle Emission Control
Information(VECI) decal lo­cated in the engine compart­ment.

- Pinches and kinks.

- Splits, cuts or breaks.

• Inspect wiring for:

- Contact with sharp edges.

- Contact with hot surfaces, such
as exhaust manifolds.

- Pinched, burned or chafed in­sulation.

- Proper routing and connec­tions.

• Check electrical connectors for:

- Corrosion on pins.

- Bent or damaged pins.

- Contacts not properly seated
in housing.

- Bad wire crimps to terminals.

3

Section 1. Multimeter Basic Functions

Digital multimeters or DMMs have many special features and functions. This
section defines these features and functions, and explains how to use these
functions to make various measurements.

1

11

5

3

8

4

6

Functions and Display Definitions

1. ROTARY SWITCH

Switch is rotated to turn multimeter
ON/OFF and select a function.

2. DC VOLTS

This function is used for measur­ing DC (Direct Current) Voltages in
the range of 0 to 500V.

3. OHMS

This function is used for measur-

ing the resistance of a component
in an electrical circuit in the range
of 0.1Ω to 20MΩ. (Ω is the electri­cal symbol for Ohms)

4.

DIODE CHECK

This function is used to check
whether a diode is good or bad.

5. HOLD

Press HOLD button to retain data

4

10

2

7
9

on display. In the hold mode, the
"H" annunciator is displayed.

6. TEST LEAD JACKS

BLACK Test Lead is

always inserted in the
COM jack.

RED Test Lead is in­serted in the jack cor­responding to the multimeter ro­tary switch setting.

Always connect TEST LEADS to the
multimeter before connecting them
to the circuit under test!!

DC AMPS

DC VOLTS AC VOLTS

OHMS DIODES

1.5V, 9V and 12V

BATTERY TESTS

7. AC VOLTS

This function is used for measur­ing AC Voltages in the range of 0
to 500V.

8. DC AMPS

This function is used for measur­ing DC (Direct Current) Amps in
the range of 0 to 10A.

9. 1.5V, 9V, AND 12V BATTERY
TEST

This function is used to test 1.5V,
9V, and 12V batteries under
load.

10. DISPLAY LIGHT

Press button to illuminate the dis­play.

11. DISPLAY

Used to display all measurements
and multimeter information.

Low Battery – If this symbol ap­pears in the lower left corner of the
display, then replace the internal
9V battery. (See Fuse and Battery

replacement on
page 7.)

High Voltage
indicator

Overrange Indi­cation – If “1” or “-

1” appears on the
left side of the dis­play, then the mul­timeter is set to a
range that is too
small for the
present measure-

ment being taken.
Increase the range until this disap­pears. If it does not disappear after
all the ranges for a particular func­tion have been tried, then the value
being measured is too large for the
multimeter to measure. (See Set­ting the Range on page 6.)

Zero Adjustment

The multimeter will automatically zero
on the Volts, Amps and Battery Test
functions.

Automatic Polarity Sensing

The multimeter display will show a minus
(-) sign on the DC Volts and DC Amps
functions when test lead hook-up is re­versed.

5

Setting the Range

Two of the most commonly asked
questions about digital multimeters
are What does Range mean? and
How do I know what Range the mul­timeter should be set to?

Fig. 2

What Does Range mean?

Range refers to the largest value
the multimeter can measure with
the rotary switch in that position. If
the multimeter is set to the 20V DC
range, then the highest voltage the
multimeter can measure is 20V in
that range.

EXAMPLE: Measuring Vehicle Bat­tery Voltage (See Fig. 1)

Fig. 1

Red

Let’s assume the multimeter is con­nected to the battery and set to the
20V range.

The display reads 12.56. This means
there is 12.56V across the battery
terminals.

Now assume we set the multimeter
to the 2000mV range. (See Fig. 2)

The multimeter display now shows
a “1” and nothing else. This means
the multimeter is being overranged
or in other words the value being
measured is larger than the current
range. The range should be in­creased until a value is shown on

Black

Red

Black

the display. If you are in the highest
range and the multimeter is still
showing that it is overranging, then
the value being measured is too
large for the multimeter to measure.

How do I know what Range the
multimeter should be set to?

The multimeter should be set in the
lowest possible range without
overranging.

EXAMPLE: Measuring an unknown
resistance

Let’s assume the multimeter is con­nected to an engine coolant sensor
with unknown resistance. (See Fig. 3)

Start by setting the multimeter to the
largest OHM range. The display
reads 0.0Ω or a short circuit.

Fig. 3

Red

Black

6

Fig. 4

Fig. 5

Fig. 6

This sensor can’t be shorted so re­duce the range setting until you get
a value of resistance.

At the 200KΩ range the multimeter
measured a value of 4.0. This means
there is 4KΩ of resistance across
the engine coolant sensor termi­nals. (See Fig. 4)

If we change the multimeter to the
20KΩ range (See Fig. 5) the dis­play shows a value of 3.87KΩ. The
actual value of resistance is 3.87KΩ
and not 4KΩ that was measured in
the 200KΩ range. This is very im­portant because if the manufacturer
specifications say that the sensor
should read 3.8-3.9KΩ at 70°F then
on the 200KΩ range the sensor
would be defective, but at the 20KΩ
range it would test good.

Now set the multimeter to the 2000Ω
range. (See Fig. 6) The display will
indicate an overrange condition be­cause 3.87KΩ is larger than 2KΩ.

This example shows that by de­creasing the range you increase the
accuracy of your measurement.
When you change the range, you
change the location of the decimal
point. This changes the accuracy of
the measurement by either increas-

ing or decreasing the number of
digits after the decimal point.

Battery and Fuse
Replacement

Important: A 9 Volt battery must be
installed before using the digital mul­timeter. (see procedure below for
installation)

Battery Replacement

1. Turn multimeter rotary
switch to OFF position.

2. Remove test leads from
multimeter.

3. Remove screws from back of
multimeter.

4. Remove back cover.

5. Install a new 9 Volt battery.

6. Re-assemble multimeter.

Fuse Replacement

1. Turn multimeter rotary
switch to OFF position.

2. Remove test leads from
multimeter.

7

3. Remove screws from back of
multimeter.

4. Remove back cover.

5. Remove fuse.

6. Replace fuse with same size
and type as originally
installed!
5mm x 20mm, 200mA, 250V,
fast acting.

7. Re-assemble multimeter.

Measuring DC Voltage

This multimeter can be used to mea­sure DC voltages in the range from 0
to 500V. You can use this multimeter
to do any DC voltage measurement
called out in the vehicle service
manual. The most common applica­tions are measuring voltage drops,
and checking if the correct voltage
arrived at or is being produced by a
sensor or a particular circuit.

To measure DC Voltages (see Fig. 7):

1. Insert BLACK test lead into
COM test lead jack.

2. Insert RED test lead into

test lead jack.

3. Connect RED test lead to posi­tive (+) side of voltage source.

4. Connect BLACK test lead to

Fig. 7

negative (-) side of voltage
source.

NOTE: If you don’t know which

side is positive (+) and which
side is negative (-), then arbi­trarily connect the RED test lead
to one side and the BLACK to
the other. The multimeter auto­matically senses polarity and will
display a minus (-) sign when
negative polarity is measured. If
you switch the RED and BLACK
test leads, positive polarity will
now be indicated on the display.
Measuring negative voltages
causes no harm to the multim­eter.

5. Turn multimeter rotary switch
to desired voltage range.

If the approximate voltage is un­known, start at the largest voltage
range and decrease to the appro­priate range as required. (See
Setting the Range on page 6)

6. View reading on display - Note
range setting for correct units.

NOTE: 200mV = 0.2V

Measuring AC Voltage

This multimeter can be used to mea­sure AC voltages in the range from
0 to 500V.

To measure AC Voltages (see Fig. 8):

Red

Black

Fig. 8

Red

Black

8

1. Insert BLACK test lead into
COM test lead jack.

2. Insert RED test lead into

test lead jack.

3. Connect RED test lead to one
side of voltage source.

4. Connect BLACK test lead to other
side of voltage source.

5. Turn multimeter rotary switch
to desired voltage range.

If the approximate voltage is un­known, start at the largest voltage
range and decrease to the appro­priate range as required. (See
Setting the Range on page 6)

6. View reading on display.

NOTE: 200mV = 0.2V

Measuring Resistance

Resistance is measured in electrical
units called ohms (Ω). The digital
multimeter can measure resistance
from 0.1Ω to 20MΩ (or 20,000,000
ohms). Infinite resistance is shown
with a “1” on the left side of display
(See Setting the Range on page 6).
You can use this multimeter to do any
resistance measurement called out
in the vehicle service manual. Test­ing ignition coils, spark plug wires,
and some engine sensors are com­mon uses for the OHMS (Ω) function.

To measure Resistance (see Fig. 9):

1. Turn circuit power OFF.

To get an accurate resistance
measurement and avoid possible
damage to the digital multimeter
and electrical circuit under test,
turn off all electrical power in the
circuit where the resistance mea­surement is being taken.

Fig. 9

Unknown

Resistance

RedBlack

2. Insert BLACK test lead into
COM test lead jack.

3. Insert RED test lead into

4. Turn multimeter rotary switch
to 200

Touch RED and BLACK multim­eter leads together and view
reading on display.

Display should read typically

0.2Ω to 1.5Ω.
If display reading was greater

than 1.5Ω, check both ends of
test leads for bad connections.
If bad connections are found,
replace test leads.

5. Connect RED and BLACK test
leads across component
where you want to measure
resistance.

When making resistance mea­surements, polarity is not im­portant. The test leads just have
to be connected across the com­ponent.

6. Turn multimeter rotary switch
to desired OHM range.

If the approximate resistance is
unknown, start at the largest OHM
range and decrease to the ap­propriate range as required. (See
Setting the Range on page 6)

9

test lead jack.

Ω range.

7. View reading on display - Note
range setting for correct units.

NOTE: 2KΩ = 2,000Ω; 2MΩ =
2,000,000Ω

If you want to make precise re­sistance measurements, then
subtract the test lead resistance
found in Step 4 above from the
display reading in Step 7. It is a
good idea to do this for resis­tance measurements less than
10Ω.

Measuring DC Current

This multimeter can be used to mea­sure DC current in the range from 0 to
10A. Unlike voltage and resistance
measurements where the multimeter
is connected across the component
you are testing, current measure­ments must be made with the multim­eter in series with the component.
Isolating current drains and short cir­cuits are some DC Current applica­tions.

Fig. 10

DC

Voltage

Source

Black

Electrical

Device

Red

To measure DC Current (see Figs.
10 & 11):

1. Insert BLACK test lead into
COM test lead jack.

2. Insert RED test lead into "10A"
test lead jack or "mA" test lead
jack.

3. Disconnect or electrically
open circuit where you want
to measure current.

This is done by:

• Disconnecting wiring harness.

• Disconnecting wire from

screw-on type terminal.

• Unsolder lead from component

if working on printed circuit
boards.

• Cut wire if there is no other

possible way to open electri­cal circuit.

4. Connect RED test lead to one
side of disconnected circuit.

5. Connect BLACK test lead to
remaining side of discon­nected circuit.

6. Turn multimeter rotary switch
to 10A DC position, 200mA or
200

µA position.

7. View reading on display.

If minus (-) sign appears on dis­play, then reverse RED and
BLACK test leads.

Fig. 11

DC

Voltage

Source

Black

Electrical

Device

Red

10

Testing Diodes

A diode is an electrical component
that allows current to only flow in one
direction. When a positive voltage,
generally greater than 0.7V, is ap­plied to the anode of a diode, the
diode will turn on and allow current to
flow. If this same voltage is applied to
the cathode, the diode would remain
off and no current would flow. There­fore, in order to test a diode, you must
check it in both directions (i.e. anode­to-cathode, and cathode-to-anode).
Diodes are typically found in alterna­tors on automobiles.

Performing Diode Test (see Fig. 12):

Fig. 12

1. Insert BLACK test lead into
COM test lead jack.

2. Insert RED test lead into

3. Turn multimeter rotary switch
to

4. Touch RED and BLACK test
leads together to test continu­ity.

Check display – should reset to

0.00.

5. Disconnect one end of diode
from circuit.

Diode must be totally isolated
from circuit in order to test its
functionality.

6. Connect RED and BLACK test

test lead jack.

function.

Anode

Cathode

Red

Black

leads across diode and view
display.

Display will show one of three
things:

• A typical voltage drop of
around 0.7V.

• A voltage drop of 0 volts.

• A “1” will appear indicating the

multimeter is overranged.

7. Switch RED and BLACK test
leads and repeat Step 6.

8. Test Results

If the display showed:

• A voltage drop of 0 volts in

both directions, then the diode
is shorted and needs to be
replaced.

• A “1” appears in both direc-

tions, then the diode is an open
circuit and needs to be re­placed.

• The diode is good if the dis-

play reads around 0.5V–0.7V
in one direction and a “1” ap­pears in the other direction
indicating the multimeter is
overranged.

11

Testing 1.5V, 9V and
12V Batteries

Test Procedure (see Fig. 13):

Fig. 13

Black

Red

1. Insert BLACK test lead into

2. Insert RED test lead into

3. Turn multimeter rotary switch

4. Connect RED test lead to posi-

5.

6. View reading on display.

Black

COM test lead jack.

to 1.5V, 9V or 12V

tive (+) terminal of battery.
Connect BLACK test lead to

negative (-) terminal of battery.

Red

test lead jack.

range.

12

Section 2. Automotive Testing

The digital multimeter is a very use­ful tool for trouble-shooting automo­tive electrical systems. This section
describes how to use the digital mul­timeter to test the starting and charg­ing system, ignition system, fuel
system, and engine sensors. The
digital multimeter can also be used
for general testing of fuses, switches,
solenoids, and relays.

General Testing

The digital multimeter can be used
to test fuses, switches, solenoids,
and relays.

Testing Fuses

This test checks to see if a fuse is
blown.

To test Fuses (see Fig. 14):

Fig. 14

Fuse

Red

Black

1. Insert BLACK test lead into
COM test lead jack.

2. Insert RED test lead into

3. Turn multimeter rotary switch
to 2000

4. Connect RED and BLACK test
leads to opposite ends of fuse.

• If the reading is zero - Fuse is

good.

test lead jack.

Ω function.

• If the reading is overrange -

Fuse is blown and needs to be
replaced.

NOTE: Always replace blown
fuses with same type and rating.

Testing Switches

This test checks to see if a switch
“Opens” and “Closes” properly.

To test Switches (see Fig. 15):

Fig. 15

1. Insert BLACK test lead into
COM test lead jack.

2. Insert RED test lead into

3. Turn multimeter rotary switch
to 2000

Ω function.

4. Connect BLACK test lead to
one side of switch.

5. Connect RED test lead to other
side of switch.

• If the reading is zero - The

switch is closed.

• If the reading is overrange -

The switch is open.

6. Operate switch.

• If the reading is zero - The

switch is closed.

13

Typical "Push"

Button Switch

Red

Black

test lead jack.

• If the reading is overrange -

The switch is open.

7. Repeat Step 6 to verify switch
operation.

Testing Solenoids
and Relays

This test checks to see if a solenoid
or relay has a broken coil. If the coil
tests good, it is still possible that the
relay or solenoid is defective. The
relay can have contacts that are
welded or worn down, and the sole­noid may stick when the coil is ener­gized. This test does not check for
those potential problems.

To test Solenoids and Relays (see
Fig. 16):

Fig. 16

Relay or
Solenoid

Black

Red

6. View reading on display.

• Typical solenoid / relay coil re­sistances are 200Ω or less.

• Refer to vehicle service manual
for the device's resistance
range.

If meter overranges, turn multi­meter rotary switch to next higher
range. (see Setting the Range
on page 6)

7. Test Results

Good Solenoid / Relay Coil:

play in Step 6 is within manufac­turers specification.

Bad Solenoid / Relay Coil:

• Display in Step 6 is not within
manufacturers specifications.

• Display reads overrange on
every ohms range indicating an
open circuit.

NOTE: Some relays and sole­noids have a diode placed across
the coil. To test this diode see
Testing Diodes on page 11.

Dis-

1. Insert BLACK test lead into
COM test lead jack.

2. Insert RED test lead into

3. Turn multimeter rotary switch
to 200

Most solenoids and relay coil
resistances are less than 200Ω.

4. Connect BLACK test lead to
one side of coil.

5. Connect RED test lead to other
side of coil.

test lead jack.

Ω function.

14

Starting/Charging System Testing

The starting system “turns over” the engine. It consists of the battery, starter
motor, starter solenoid and/or relay, and associated wiring and connections.
The charging system keeps the battery charged when the engine is running.
This system consists of the alternator, voltage regulator, battery, and
associated wiring and connections. The digital multimeter is a useful tool for
checking the operation of these systems.

No Load Battery Test

Before you do any starting/charging
system checks, you must first test
the battery to make sure it is fully
charged.

Test Procedure (see Fig. 17):

Fig. 17

Red

Black

1. Turn Ignition Key OFF.

2. Turn ON headlights for 10 sec­onds to dissipate battery sur­face charge.

3. Insert BLACK test lead into
COM test lead jack.

4. Insert RED test lead into

test lead jack.

5. Disconnect positive (+) battery
cable.

6. Connect RED test lead to posi­tive (+) terminal of battery.

7.

Connect BLACK test lead to
negative (-) terminal of battery.

8. Turn multimeter rotary switch
to 20V DC range.

9. View reading on display.

10.Test Results.

Compare display reading in Step
9 with the following chart.

Voltage Battery is Charged

12.60V
or greater 100%

12.45V 75%

12.30V 50%

12.15V 25%

If battery is not 100% charged, then
charge it before doing anymore start­ing/charging system tests.

Percent

15

Engine Off Battery
Current Draw

This test measures the amount of
current being drawn from the battery
when the ignition key and engine are
both off. This test helps to identify
possible sources of excessive bat­tery current drain, which could even­tually lead to a “dead” battery.

1. Turn Ignition Key and all ac­cessories OFF.

Make sure trunk, hood, and
dome lights are all OFF.

(See Fig. 18)

Fig. 18

Black

2. Insert BLACK test lead into
COM test lead jack.

3. Insert RED test lead into "10A"
(or "mA") test lead jack.

4. Disconnect positive (+) battery
cable.

5. Connect RED test lead to posi­tive (+) battery terminal.

6. Connect BLACK test lead to
positive (+) battery cable.

NOTE: Do not start vehicle dur­ing this test, because multimeter
damage may result.

7. Turn multimeter rotary switch
to 10A DC (or 200 mA) posi­tion.

8. View reading on display.

• Typical current draw is 100mA.

(1mA = 0.001A)

Red

• Refer to vehicle service manual
for manufacturers specific En­gine Off Battery Current Draw.

NOTE: Radio station presets
and clocks are accounted for in
the 100mA typical current draw.

9. Test Results.

Normal Current Draw:

reading in Step 8 is within manu­facturers specifications.

Excessive Current Draw:

- Display reading in Step 8 is
well outside manufacturers
specifications.

- Remove Fuses from fuse box
one at a time until source of
excessive current draw is lo­cated.

- Non-Fused circuits such as
headlights, relays, and sole­noids should also be checked
as possible current drains on
battery.

- When source of excessive cur­rent drain is found, service as
necessary.

16

Display

Cranking Voltage ­Battery Load Test

This test checks the battery to see if it
is delivering enough voltage to the
starter motor under cranking conditions.

Test Procedure (see Fig. 19):

Fig. 19

Red

1. Disable ignition system so ve­hicle won’t start.

Disconnect the primary of the
ignition coil or the distributor pick­up coil or the cam/crank sensor
to disable the ignition system.
Refer to vehicle service manual
for disabling procedure.

2. Insert BLACK test lead into
COM test lead jack.

3. Insert RED test lead into

test lead jack.

4. Connect RED test lead to posi­tive (+) terminal of battery.

Black

5.

Connect BLACK test lead to
negative (-) terminal of battery.

6. Turn multimeter rotary switch
to 20V DC range.

7. Crank engine for 15 seconds
continuously while observing
display.

8. Test Results.

Compare display reading in Step
7 with chart below.

Voltage Temperature

9.6V or greater70 °F and Above

9.5V 60 °F

9.4V 50 °F

9.3V 40 °F

9.1V 30 °F

8.9V 20 °F

8.7V 10 °F

8.5V 0 °F

If voltage on display corresponds to
above voltage vs. temperature chart,
then cranking system is normal.

If voltage on display does not corre­spond to chart, then it is possible
that the battery, battery cables, start­ing system cables, starter solenoid,
or starter motor are defective.

17

Voltage Drops

This test measures the voltage drop across wires, switches, cables, solenoids,
and connections. With this test you can find excessive resistance in the starter
system. This resistance restricts the amount of current that reaches the starter
motor resulting in low battery load voltage and a slow cranking engine at starting.

Test Procedure (see Fig. 20):

1. Disable ignition system so ve­hicle won’t start.

Disconnect the primary of the
ignition coil or the distributor pick­up coil or the cam/crank sensor
to disable the ignition system.
Refer to vehicle service manual
for disabling procedure.

2. Insert BLACK test lead into
COM test lead jack.

3. Insert RED test lead into

test lead jack.

4. Connect test leads.

Refer to Typical Cranking Volt­age Loss Circuit (Fig. 20).

•

Connect RED and BLACK test
leads alternately between 1 & 2,
2 & 3, 4 & 5, 5 & 6, 6 & 7, 7 & 9,
8 & 9, and 8 & 10.

Fig. 20 Typical Cranking Voltage

Loss Circuit

This is a representative
sample of one type of
cranking circuit. Your vehicle
may use a different circuit
with different components or
locations. Consult your
vehicle service manual.

5. Turn multimeter rotary switch
to 200mV DC range.

If multimeter overranges, turn mul­timeter rotary switch to the
2000mV DC range. (See Setting
the Range on page 6)

6. Crank engine until steady
reading is on display.

• Record results at each point

as displayed on multimeter.

• Repeat Step 4 & 5 until all

points are checked.

7. Test Results –

Estimated Voltage Drop of
Starter Circuit Components

Component Voltage

Switches 300mV
Wire or Cable 200mV
Ground 100mV

Solenoid

Red Black

Starter

18

Component Voltage

Battery Cable
Connectors 50mV

Connections 0.0V

• Compare voltage readings in
Step 6 with above chart.

•

If any voltages read high, inspect
component and connection for
defects.

• If defects are found, service as
necessary.

Charging System Voltage Test

This test checks the charging sys­tem to see if it charges the battery
and provides power to the rest of the
vehicles electrical systems (lights,
fan, radio etc).

Test Procedure (see Fig. 21):

Fig. 21

Black

1. Insert BLACK test lead into
COM test lead jack.

2. Insert RED test lead into

3. Turn multimeter rotary switch
to 20V DC range.

4. Connect RED test lead to posi­tive (+) terminal of battery.

5.

Connect BLACK test lead to
negative (-) terminal of battery.

6. Start engine - Let idle.

Red

test lead jack.

7. Turn off all accessories and
view reading on display.

• Charging system is normal if

display reads 13.2 to 15.2 volts.

• If display voltage is not be-

tween 13.2 to 15.2 volts, then
proceed to Step 13.

8. Open throttle and Hold engine
speed (RPM) between 1800 and
2800 RPM.

Hold this speed through Step 11 ­Have an assistant help hold
speed.

9. View reading on display.

Voltage reading should not
change from Step 7 by more
than 0.5V.

10.Load the electrical system by
turning on the lights, wind­shield wipers, and setting the
blower fan on high.

11.View reading on display.

Voltage should not drop down
below about 13.0V.

12.Shut off all accessories, re­turn engine to curb idle and
shut off.

19

13.Test Results.

• If voltage readings in Steps 7,
9, and 11 were as expected,
then charging system is nor­mal.

• If any voltage readings in Steps
7, 9, and 11 were different then
shown here or in vehicle ser­vice manual, then check for a
loose alternator belt, defective
regulator or alternator, poor
connections, or open alterna­tor field current.

• Refer to vehicle service manual
for further diagnosis.

20

Ignition System Testing

The ignition system is responsible for providing the spark that ignites the fuel in
the cylinder. Ignition system components that the digital multimeter can test are
the primary and secondary ignition coil resistance, spark plug wire resistance
and reluctance pick-up coil sensors.

Ignition Coil Testing

This test measures the resistance
of the primary and secondary of an
ignition coil. This test can be used
for distributorless ignition systems
(DIS) provided the primary and sec­ondary ignition coil terminals are
easily accessible.

Test Procedure:

1. If engine is HOT let it COOL

down before proceeding.

2. Disconnect ignition coil from

ignition system.

3. Insert BLACK test lead into

COM test lead jack (see Fig.

22).

4. Insert RED test lead into

5. Turn multimeter rotary switch

to 200

6. Touch RED and BLACK multi-

meter leads together and view
reading on display.

Fig. 22

test lead jack.

Ω range.

Secondary

Red

Typical Cylindrical

Ignition Coil

7. Connect test leads.

• Connect RED test lead to pri­mary ignition coil positive (+)
terminal.

• Connect BLACK test lead to pri­mary ignition coil negative (-)
terminal.

• Refer to vehicle service manual
for location of primary ignition
coil terminals.

8. View reading on display.

Subtract test lead resistance found
in Step 6 from above reading.

9. If vehicle is DIS, repeat Steps 7
and 8 for remaining ignition
coils.

10.Test Results - Primary Coil

• Typical resistance range of pri-

mary ignition coils is 0.3 - 2.0Ω.

• Refer to vehicle service manual

for your vehicles resistance range.

11.Turn multi-

Coil

Black

12.Move RED

Primary

Coil

21

meter rotary
switch to
200kΩ range
(see Fig. 23).

test lead to
secondary ig­nition coil ter­minal.

• Refer to ve­hicle service

Fig. 23

Secondary

Coil

Red

Black

Typical Cylindrical

Ignition Coil

Primary

Coil

manual for location of second­ary ignition coil terminal.

• Verify BLACK test lead is con­nected to primary ignition coil
negative (-) terminal.

13.View reading on display.

14.If vehicle is DIS, connect test
leads to terminals of the sec­ondary ignition coil. Repeat
for remaining ignition coils.

15.Test Results - Secondary Coil

• Typical resistance range of

secondary ignition coils is

6.0kΩ - 30.0kΩ.

• Refer to vehicle service

manual for your vehicles re­sistance range.

16.Repeat test procedure for a
HOT ignition coil.

NOTE: It is a good idea to test
ignition coils when they are both
hot and cold, because the resis­tance of the coil could change
with temperature. This will also
help in diagnosing intermittent
ignition system problems.

17.Test Results - Overall

Good Ignition Coil:

Resistance
readings in Steps 10, 15 and 16
were within manufacturers speci­fication.

Bad Ignition Coil:

Resistance
readings in Steps 10, 15 and 16
are not within manufacturers
specification.

22

Ignition System Wires

This test measures the re­sistance of spark plug and
coil tower wires while they
are being flexed. This test
can be used for
distributorless ignition sys­tems (DIS) provided the sys­tem does not mount the igni­tion coil directly on the spark
plug.

Test Procedure:

1. Remove ignition sys­tem wires one at a time from
engine.

• Always grasp ignition system

wires on the boot when removing.

• Twist the boots about a half

turn while pulling gently to re­move them.

• Refer to vehicle service manual

for ignition wire removal pro­cedure.

• Inspect ignition wires for

cracks, chaffed insulation, and
corroded ends.

NOTE: Some Chrysler products
use a “positive-locking” terminal
electrode spark plug wire. These
wires can only be removed from
inside the distributor cap. Dam­age may result if other means of
removal are attempted. Refer to
vehicle service manual for pro­cedure.

NOTE: Some spark plug wires
have sheet metal jackets with
the following symbol:
type of plug wire contains an “air
gap” resistor and can only be
checked with an oscilloscope.

2. Insert BLACK test lead into
COM test lead jack (see Fig.

24).

Fig. 24

. This

Black

Red

Spark Plug Wire

3. Insert RED test lead into

4. Connect RED test lead to one
end of ignition wire and
BLACK test lead to other end.

5. Turn multimeter rotary switch
to 200K

6. View reading on display while
flexing ignition wire and boot
in several places.

• Typical resistance range is

3KΩ to 50KΩ or approximately
10KΩ per foot of wire.

• Refer to vehicle service manual

for your vehicles resistance
range.

• As you flex ignition wire, the

display should remain steady.

7. Test Results

Good Ignition Wire:

reading is within manufacturers
specification and remains steady
while wire is flexed.

Bad Ignition Wire:

ing erratically changes as igni­tion wire is flexed or display read­ing is not within manufacturers
specification.

23

test lead jack.

Ω range.

Display

Display read-

Magnetic Pick-Up Coils – Reluctance Sensors

Reluctance sensors are used when­ever the vehicle computer needs to
know speed and position of a rotat­ing object. Reluctance sensors are
commonly used in ignition systems
to determine camshaft and crank­shaft position so the vehicle com­puter knows the optimum time to fire
the ignition coil(s) and turn on the
fuel injectors. This test checks the
reluctance sensor for an open or
shorted coil. This test does not check
the air gap or voltage output of the
sensor.

Test Procedure (see Fig. 25):

Fig. 25

Reluctance

Sensor

Reluctor

Ring

Magnet

Black

1. Insert BLACK test lead into
COM test lead jack.

2. Insert RED test lead into

3. Connect RED test lead to ei­ther sensor pin.

4. Connect BLACK test lead to
remaining sensor pin.

Red

test lead jack.

5. Turn multimeter rotary switch

to 2000Ω range.

6. View reading on display while
flexing sensor wires in sev­eral places.

• Typical resistance range is 150

- 1000Ω.

• Refer to vehicle service manual

for your vehicles resistance
range.

• As you flex sensor wires, the

display should remain steady.

7. Test Results

Good Sensor:

Dis­play reading is within
manufacturers speci­fication and remains
steady while sensor
wires are flexed.

Bad Sensor:

Display
reading erratically
changes as sensor
wires are flexed or
display reading is not
within manufacturers
specification.

24

Fuel System Testing

The requirements for lower vehicle emissions has increased the need for
more precise engine fuel control. Auto manufacturers began using elec­tronically controlled carburetors in 1980 to meet emission requirements.
Today’s modern vehicles use electronic fuel injection to precisely control
fuel and further lower emissions. The digital multimeter can be used to
measure fuel injector resistance.

Measuring Fuel Injector Resistance

Fuel injectors are similar to sole­noids. They contain a coil that is
switched ON and OFF by the ve­hicle computer. This test measures
the resistance of this coil to make
sure it is not an open circuit. Shorted
coils can also be detected if the
specific manufacturer resistance of
the fuel injector is known.

Test Procedure (see Fig. 26):

Fig. 26

1. Insert BLACK test lead into
COM test lead jack.

2. Insert RED test lead into

3. Turn multimeter rotary switch
to 200

Touch RED and BLACK multim­eter leads together and view
reading on display.

Display should read typically 0.2 -

1.5Ω.

test lead jack.

Ω range.

Typical

Fuel Injector

Black

If display reading was greater
than 1.5Ω, check both ends of
test leads for bad connections. If
bad connections are found, re­place test leads.

4. Disconnect wiring harness

from fuel injector - Refer to
vehicle service manual for pro­cedure.

5. Connect RED and BLACK
test leads across fuel in­jector pins.

Make sure you connect test
leads across fuel injector

and not the wiring harness.

6. Turn multimeter rotary

Red

7. View reading on display - Note

25

switch to desired OHM
range.

If the approximate resis­tance is unknown, start at
the largest OHM range and
decrease to the appropri-

ate range as required. (see Set­ting the Range on page 6)

range setting for correct units.

• If display reading is 10Ω or
less, subtract test lead resis­tance found in Step 3 from
above reading.

• Compare reading to manufac­turers specifications for fuel in­jector coil resistance.

• This information is found in
vehicle service manual.

8. Test Results

Good Fuel Injector resistance:

Resistance of fuel injector coil is
within manufacturers specifica­tions.

Bad Fuel Injector resistance:

sistance of fuel injector coil is
not within manufacturers speci­fications.

NOTE: If resistance of fuel in­jector coil is within manufactur­ers specifications, the fuel injec­tor could still be defective. It is
possible that the fuel injector is
clogged or dirty and that is caus­ing your driveability problem.

Re-

26

Testing Engine Sensors

In the early 1980’s, computer controls were installed in vehicles to meet
Federal Government regulations for lower emissions and better fuel economy.
To do its job, a computer-controlled engine uses electronic sensors to find
out what is happening in the engine. The job of the sensor is to take
something the computer needs to know, such as engine temperature, and
convert it to an electrical signal which the computer can understand. The
digital multimeter is a useful tool for checking sensor operation.

Oxygen (O2) Type Sensors

The Oxygen Sensor produces a volt­age or resistance based on the
amount of oxygen in the exhaust
stream. A low voltage (high resis­tance) indicates a lean exhaust (too
much oxygen), while a high voltage
(low resistance) indicates a rich ex­haust (not enough oxygen). The
computer uses this voltage to ad­just the air/fuel ratio. The two types

Sensors commonly in use are

of O

2

Zirconia and Titania. Refer to illus­tration for appearance differences
of the two sensor types.

Test Procedure (see Fig. 27):

1. If engine is HOT, let it COOL

down before proceeding.

Fig. 27

Rich Lean

Red

Titania-Type

Oxygen Sensor

Exposed

flat element

Zirconia-Type

Oxygen Sensor

Flutes

2. Remove Oxygen Sensor from
vehicle.

3. Insert BLACK test lead into
COM test lead jack.

4. Insert RED test lead into

test lead jack.

Black

Ground

1-wire or 3-wire: Ground is sensor housing
2-wire or 4-wire: Ground is in sensor wiring

harness

27

5. Test heater circuit.

• If sensor contains 3 or more
wires, then your vehicle uses a
heated O

sensor.

2

• Refer to vehicle service manual
for location of heater pins.

• Connect RED test lead to ei­ther heater pin.

• Connect BLACK test lead to
remaining heater pin.

• Turn multimeter rotary switch
to 200Ω range.

• View reading on display.

• Compare reading to

manufacturer's specification in
vehicle service manual.

• Remove both test leads from
sensor.

6. Connect BLACK test lead to
sensor GROUND pin.

• If sensor is 1-wire or 3-wire, then

GROUND is sensor housing.

• If sensor is 2-wire or 4-wire,

then GROUND is in sensor wir­ing harness.

• Refer to vehicle service manual

for Oxygen Sensor wiring dia­gram.

7. Connect RED test lead to sen­sor SIGNAL pin.

8. Test Oxygen Sensor.

• Turn multimeter rotary switch

to...
– 2000mV range for Zirconia

Type Sensors.
– 200KΩ range for Titania Type

Sensors.

• Light propane torch.

• Firmly grasp sensor with a pair

of locking pliers.

• Thoroughly heat sensor tip as
hot as possible, but not “glow­ing.” Sensor tip must be at
660°F to operate.

• Completely surround sensor tip
with flame to deplete sensor of
oxygen (Rich Condition).

• Multimeter display should
read...

– 600mV or greater for Zirco­nia Type Sensors.

– an Ohmic(Resistance) value
for Titania Type Sensors.
Reading will vary with flame
temperature.

• While still applying heat to sen­sor, move flame such that oxy­gen can reach sensor tip (Lean
Condition).

• Multimeter display should
read...

– 400mV or less for Zirconia
Type Sensors.

– an overrange condition for
Titania Type Sensors. (See
Setting the Range on page 6.)

9. Repeat Step 8 a few times to
verify results.

10. Extinguish Flame, let sensor
cool, and remove test leads.

11.Test Results.

Good Sensor:

• Heater Circuit resistance is

within manufacturer's specifi­cation.

• Oxygen Sensor output signal

changed when exposed to a
rich and lean condition.

Bad Sensor:

• Heater Circuit resistance is not

within manufacturer's specifi­cation.

28

• Oxygen Sensor output signal
did not change when exposed
to a rich and lean condition.

• Oxygen sensor output voltage
takes longer than 3 seconds
to switch from a rich to a lean
condition.

Temperature Type
Sensors

A temperature sensor is a thermistor
or a resistor whose resistance
changes with temperature. The hot­ter the sensor gets, the lower the
resistance becomes. Typical ther­mistor applications are engine cool­ant sensors, intake air temperature
sensors, transmission fluid tempera­ture sensors, and oil temperature
sensors.

Test Procedure (see Fig. 28):

Fig. 28

1. If engine is HOT let it COOL
down before proceeding.

Make sure all engine and trans­mission fluids are at outside air
temperature before proceeding
with this test!

2. Insert BLACK test lead into
COM test lead jack.

Hair Dryer

Red

Typical

Intake Air

Temperature

Sensor

Black

3. Insert RED test lead into
test lead jack.

4. Disconnect wiring harness

from sensor.

5. If testing Intake Air Tempera-

ture Sensor - Remove it from
vehicle.

All other temperature sensors
can remain on vehicle for test­ing.

6. Connect RED test lead to ei-

ther sensor pin.

7. Connect BLACK test lead to

remaining sensor pin.

8. Turn multimeter rotary switch

to desired OHM range.

If the approximate resistance is
unknown, start at the largest OHM
range and decrease to the appro­priate range as required. (See
Setting the Range on page 6.)

9. View and record reading on

display.

10.Disconnect multimeter test

leads from sensor and recon­nect sensor wiring.

This step does not apply to in­take air temperature sensors. For
intake air temperature sensors,
leave multimeter test leads still
connected to sensor.

11.Heat up sensor.

If testing Intake Air Temperature
Sensor:

• To heat up sensor dip sensor
tip into boiling water, or...

• Heat tip with a

lighter if sensor
tip is metal or a hair dryer if
sensor tip is plastic.

• View and record smallest read­ing on display as sensor is
heated.

• You may need to decrease the

29

range to get a more accurate
reading.

For all other temperature sen­sors:

• Start engine and let idle until
upper radiator hose is warm.

• Turn ignition key OFF.

• Disconnect sensor wiring har-

ness and reconnect multimeter
test leads.

• View and record reading on
display.

12.Test Results.

Good Sensor:

• Temperature sensors HOT re­sistance is at least 300Ω less
than its COLD resistance.

• The key point is that the COLD
resistance decreases with in­creasing temperature.

Bad Sensor:

• There is no change between
the temperature sensors HOT
resistance from the COLD re­sistance.

• The temperature sensor is an
open or a short circuit.

Position Type
Sensors

Position sensors are potentiometers
or a type of variable resistor. They
are used by the computer to deter­mine position and direction of move­ment of a mechanical device. Typi­cal position sensor applications are
throttle position sensors, EGR valve
position sensors, and vane air flow
sensors.

Test Procedure (see Fig. 29):

1. Insert BLACK test lead into
COM test lead jack.

2. Insert RED test lead into

3. Disconnect wiring harness
from sensor.

4. Connect Test Leads.

• Connect RED test lead to sen-

sor POWER pin.

• Connect BLACK test lead to

sensor GROUND pin.

• Refer to vehicle service manual

for location of sensor POWER
and GROUND pins.

5. Turn multimeter rotary switch
to 20K

test lead jack.

Ω range.

Fig. 29

30

Typical Toyota Throttle

Position Sensor

Red

POWER GROUND

SIGNAL IDLE SWITCH

Black

6. View and record reading on
display.

• Display should read some re-

sistance value.

• If multimeter is overranging, ad-

just the range accordingly. (See
Setting the Range on page 6.)

• If multimeter overranges on larg-

est range, then sensor is an
open circuit and is defective.

7. Move RED test lead to sensor
SIGNAL pin.

• Refer to vehicle service manual

for location of sensor SIGNAL pin.

8. Operate Sensor.

Throttle Position Sensor:

• Slowly move throttle linkage

from closed to wide open posi­tion.

• Depending on hook-up, the dis-

play reading will either
crease or decrease in resis­tance.

• The display reading should ei-

ther

start at or end at the ap­proximate resistance value
measured in Step 6.

• Some throttle position sensors
have an Idle or Wide Open
Throttle (WOT) switch in addi­tion to a potentiometer.

• To test these switches, follow
the Testing Switches test pro­cedure on page 13.

• When you are told to operate
switch, then move throttle link­age.

in-

Vane Air Flow Sensor:

• Slowly open vane “door” from
closed to open by pushing on it
with a pencil or similar object.
This will not harm sensor.

• Depending on hook-up, the dis­play reading will either
or decrease in resistance.

• The display reading should ei-
ther start at or end at the ap-

proximate resistance value mea­sured in Step 6.

• Some vane air flow sensors
have an idle switch and an in­take air temperature sensor in
addition to a potentiometer.

• To test idle switch see Testing
Switches on page 13.

• When you are told to operate
switch, then open vane “door”.

• To test intake air temperature
sensor see Temperature Type
Sensors on page 29.

EGR Valve Position

• Remove vacuum hose from
EGR valve.

• Connect hand vacuum pump
to EGR valve.

• Gradually apply vacuum to
slowly open valve. (Typically,
5 to 10 in. of vacuum fully opens
valve.)

• Depending on hook-up, the dis­play reading will either
or decrease in resistance.

• The display reading should ei-
ther start at or end at the ap-

proximate resistance value mea­sured in Step 6.

9. Test Results.

Good Sensor:

ing gradually increases or de­creases in resistance as sensor
is opened and closed.

Bad Sensor:

in resistance as sensor is opened
or closed.

31

There is no change

increase

increase

Display read-

Electrical
Specifications

DC Volts

Range: 200mV, 2000mV, 20V, 200V
Accuracy : ±(0.5% rdg + 2 dgts)

Range: 500V
Accuracy: ±(0.8% rdg + 2 dgts)

AC Volts

Range: 200V, 500V
Accuracy : ±(1.2% rdg + 10 dgts)

DC Current

Range: 200µA
Accuracy: ±(1.0% rdg + 2 dgts)

Range: 200mA
Accuracy: ±(1.2% rdg + 2 dgts)

Range: 10A
Accuracy: ±(2.0% rdg + 5 dgts)

Resistance

Range: 200Ω
Accuracy: ±(0.8% rdg + 5 dgts)

Range: 2000Ω, 20KΩ, 200KΩ
Accuracy: ±(0.8% rdg + 2 dgts)

Range: 20MΩ
Accuracy: ±(1.0% rdg + 5 dgts)

Battery Test

Range: 1.5V, 9V, 12V
Accuracy: ±(10% rdg + 2 dgts)

Diode Test

Resolution: 1mV

32