Actron CP7677 User Manual

Auto TroubleShooter

™

OPERATING

INSTRUCTIONS

Index

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

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

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

Electrical Specifications ............................... 34

Warranty ..................................................... 104

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.............................. 9

Testing f or C on ti nu i ty .............................. 10

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

Measuring Engine RPM.......................... 11

Measuring Dwell ..................................... 12

2. Automotive Testing with the CP7677

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

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

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

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

Starting / Charging System Testing ....... 15

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

- Engine Off Battery Current Draw ........ 15

CP7677

- Cranking Voltage/Battery Load Test ... 16

- Voltage Drops ...................................... 17

- Charging System Voltage Test ........... 18

Ignition System Testing .......................... 19

- Igni t io n C o il Te s ti ng ............................. 19

- Ignition System Wires.......................... 21

- Hall Effect Sensors/Switches .............. 22

- Magnetic Pick-Up Coils ....................... 23

- Reluctance Sensors ............................ 23

- Igni t io n C o il Sw i tc hi n g A ct i on .............. 24

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

- Testing GM C-3 Mixture Control

Solenoid Dwell .................................... 25

- Measuring Fuel Injector Resistance ... 26

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

- Oxygen (O2) Type Sensors ................. 27

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

- Position Type Sensors –
Throttle and EGR Valve Position,

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

- Manifold Absolute Pressure (MAP) and
Barometric Pressure (BARO) Sensors 31

- Mass Air Flow (MAF) Sensors ............ 32

Instrucciones en español ....35

Instructions en français.......6 9

1

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

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.

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

must

follow vehicle service

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 vehicle
service manual, or Vehicle 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.

12

10

11

9

8

7

6

Alligator Clip Adapters

Some multimeter tests and measurements are more easily done using
alligator clips instead of test prods. For these tests, push the crimp end of the
alligator clip onto the test prod. If the crimp on the alligator clip becomes loose,
then remove the alligator clip from the test prod and re-crimp using a pair of
pliers.

5

4

3

2

1

4

Functions and Display Definitions

1. ROTARY SWITCH

Switch is rotated to select a function.

2. DC VOLTS

This function is used for measuring DC
(Direct Current) Voltages in the range
of 0 to 1000V.

3. OHMS

This function is used for measuring 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 / CONTINUITY TESTS

This function is used to check whether a
diode is good or bad. It is also used for
fast continuity checks of wires and ter­minals. An audible tone will sound if a
wire and terminal are good.

5. HOLD

Press HOLD button to retain data on
display. In the hold mode, the "H" an­nunciator is displayed.

6. TEST LEAD JACKS

BLACK Test Lead is al-

ways inserted in the COM
jack.

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

DC VOLTS

DC AMPS

RPM

DWELL

OHMS

AC VOLTS

DIODES

CONTINUITY

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

7. AC VOLTS

This function is used for measuring AC
Voltages in the range of 0 to 750V.

8. DC AMPS

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

9. DWELL

This function is used for measuring
DWELL on distributor ignition systems,
and solenoids.

10. TACH

This function is used for measuring
engine speed (RPM).

11. ON/OFF

Press to turn power ON. Press again to
turn power OFF.

12. 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.)

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 measurement
being taken. Increase
the range until this dis-

appears. 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 RPM 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?

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

Black

Red

Now assume we set the multimeter to
the 2V 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
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)

Fig. 3

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.

Fig. 2

Black

Red

Red

Black

Start by setting the multimeter to the
largest OHM range. The display reads

0.0Ω or a short circuit.
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

6

Fig. 4

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 2KΩ 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

Fig. 5

Fig. 6

the accuracy of the measurement by ei­ther increasing 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 OFF.

2. Remove test leads from
multimeter.

3. Remove screw from battery
cover.

4. Remove battery cover.

5. Install a new 9 Volt battery.

6. Re-assemble multimeter.

Fuse Replacement

1. Turn multimeter OFF.

2. Remove test leads from
multimeter.

3. Remove rubber holster.

4. Remove screw from battery
cover, battery cover, and battery.

5. Remove screws from back of
multimeter.

6. Remove back cover.

7. Remove fuse.

8. Replace fuse with same size and
type as originally installed.

Use a 1/4" x 1-1/4", 10A, 250V, fast
acting fuse or a 5mm x 20mm
315mA, 250V fast acting fuse.

9. Re-assemble multimeter.

7

Measuring DC Voltage

This multimeter can be used to measure
DC voltages in the range from 0 to 1000V.
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 a sensor or a particular circuit.

To measure DC Voltages (see Fig. 7):

Fig. 7

Red

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

2. Insert RED test lead into

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

4. Connect BLACK test lead to 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)

Black

test lead jack.

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 750V.

To measure AC Voltages (see Fig. 8):

Fig. 8

Red

Black

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
range setting for correct units.

NOTE: 200mV = 0.2V

8

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):

Fig. 9

Unknown

Resistance

Red Black

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.

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

3. Insert RED test lead into

4. Turn multimeter rotary switch to
200

Ω range.

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 measure-

test lead jack.

ments, 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)

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. If
the current you are measuring exceeds
10A, the internal fuse will blow (see Fuse
Replacement on page 7). 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.

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

9

Fig. 10

DC
Voltage
Source

Black

Fig. 11

DC
Voltage

Source

Electrical

Device

Red

Electrical

Device

Red

Testing for Continuity

Continuity is a quick way to do a resis­tance test to determine if a circuit is
open or closed. The multimeter will beep
when the circuit is closed or shorted, so
you don’t have to look at the display.
Continuity checks are usually done when
checking for blown fuses, switch opera­tion, and open or shorted wires.

To measure Continuity (see Fig. 12):

Fig. 12

Black

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, or 200mA posi­tion.

7. View reading on display.

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

Red

Black

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

2. Insert RED test lead into

test lead jack.

3. Turn multimeter rotary switch to

function.

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

Listen for tone to verify proper op­eration.

5. Connect RED and BLACK test
leads across component where
you want to check for continuity.

Listen for tone:

• If you hear tone – Circuit is closed

or shorted.

• If you don’t hear tone – Circuit is

open.

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.
anode-to-cathode, and cathode-to-an­ode). Diodes are typically found in alter­nators on automobiles.

Performing Diode Test (see Fig. 13):

Fig. 13

Cathode

Anode

Red

Black

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
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 mul-

timeter is overranged.

test lead jack.

function.

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 directions,

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

• The diode is good if the display

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

Measuring Engine RPM

RPM refers to revolutions per minute.
When using this function you must multi­ply the display reading by 10 to get actual
RPM. If display reads 200 and the multim­eter is set to 6 cylinder RPM, the actual
engine RPM is 10 times 200 or 2000 RPM.

To measure Engine RPM (see Fig. 14):

Fig. 14

Typical

Ignition

Coil

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

2. Insert RED test lead into

3. Connect RED test lead to TACH
(RPM) signal wire.

• If vehicle is DIS (Distributorless

• For all vehicles with distributors,

11

Red

Black

Ground

test lead jack.

Ignition System), then connect RED
test lead to the TACH signal wire
going from the DIS module to the
vehicle engine computer. (refer to
vehicle service manual for location
of this wire)