Page 1
BEST 6042
ASSOCIATED
B
ATTERY ELECTRICAL SYSTEMS TESTER
OPERATOR AND SAFETY MANUAL
The B.E.S.T. tester is designed to test electrical systems on 12, 12/24, and 24 volt vehicles. It can test and evaluate
starters, batteries, alternators, regulators, wiring connections, and other electrical equipment in the low voltage
circuits in the vehicle. Before operating this unit, thoroughly familiarize yourself with the safety instructions included in
this booklet and in the service manual.
TABLE OF CONTENTS
Features.......................................................................1
Safety instructions .......................................................2
Battery Load Tests.......................................................3
Starter Tests ................................................................5
Charging System Tests ...............................................5
Trouble Shooting Hints................................................7
Assembly Instructions..................................................8
FEATURES OF THE B.E.S.T. INCLUDE:
Large, easy to read, LED digital AMPS and
VOLTS meters. The VOLTS meter reads voltages
to ±99.9 volts DC on the EXT position and up to
35.0 volts DC on the INT position. The AMPS
meter reads DC currents up to 999 amps.
The input impedance of the meters is 10 Meg
ohms for accurate testing of solid state circuits.
The carbon pile is rated 500 amps on 12 volt
batteries for load testing batteries up to 1000 CCA
capacity.
Curved carbon discs allow better low end
resolution of current and longer life.
AMPS ZERO ADJUST allows for maximum
accuracy in AMPS reading.
LOAD ON light indicates the carbon pile is
actuated and serves as a reminder to turn the load
off (full counter-clockwise position).
AMPS meter reads both + and - amps for easy
diagnosis of leakage current problems.
DEFECTIVE DIODE indicator light lets you know
when alternator output diodes or GM diode trios
have failed.
The electronic circuits are protected by a fuse
against excessive voltage inputs that will damage
the unit. LED indicators on the circuit board allow
for easy diagnosis of fuse or other problems.
The electronic circuits are protected against
reverse voltages caused by connecting leads
incorrectly.
The electronic circuit board has a protective
coating to prevent damage and meter inaccuracy
due to moisture and dirt.
AMP
DEFECTIVE
ADJUST
LOAD ADJUST
LOAD
ON
DIODE
VOLTSFIELD
6042
SAFETY INSTRUCTIO N
AMPSVOLTS
ASSOCIATED
The FIELD selector switch is spring loaded and
always returns to an off position so there is no
power on the field lead when not in use.
The field wire (blue) is supplied to allow for
regulator trouble shooting. The lead may be
switched to negative (A) or positive (B) polarity
depending on the application. The lead has a
circuit breaker in it to prevent damage if
accidentally shorted out when in use.
Heavy duty leads are single extended so the may
be used for testing at points up to 15 feet apart.
The clamps on the heavy duty lead are vinyl
dipped and have a flexi-spring stain relief to
prevent cable damage. Solid copper jaws provide
better electrical conduction and are field
replaceable.
Heavy duty leads have internal tracer lead wires
for voltage readings where the clamps are
attached when the VOLTS switch is in the internal
(INT) position. These leads should not be
attached to any voltage source that could rise
above 35 VDC.
The light gauge voltage sensing leads (red and
black) have small test clips to allow testing at
points where the heavy duty leads can not reach.
Use the leads when the VOLTS switch is in the
external (EXT) position. The leads can test points
in a vehicle up to 15 feet apart and read voltages
up to 99.9 VDC.
The inductive AMPS PICKUP has 10 foot long
lead to allow for testing in hard to reach areas.
All leads are long enough to test trucks, "high-rise"
four wheel drive, or off road vehicles.
The cart has a long wheelbase for greater stability
when moved over rough surfaces or cracked
floors.
1
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IMPORTANT SAFETY INSTRUCTIONS
SAVE THESE INSTRUCTIONS. The safety information contained herein should be
reviewed every time the unit is used.
BATTERY SAFETY:
ALWAYS WEAR EYE PROTECTION WHEN WORKING NEAR A
BATTERY.
CAUTION: The electrolyte in automotive batteries is
sulfuric acid, which is capable of causing severe damage to skin,
eyes, and clothing. When contact with battery acid occurs, proceed
as follows:
1) Eyes: Force open and flood with cool running water at
least for 10 minutes, then see a doctor. Never use eye
drops or other medication before seeing a doctor.
2) Remove contaminated clothing and flood skin for at least
While batteries are being charged or tested, an explosive gas
mixture forms inside each cell. Some of this gas escape through the
vent holes in the filler caps and may remain around the battery in an
explosive condition. Sparks or flames igniting this gas mixture will
burn back through the vent hole and explode inside the battery cell.
Such an explosion is dangerous not only because of its own force,
but also because of the acid electrolyte which could spray onto
anything in the vicinity.
TO PREVENT EXPLOSIONS:
1) Use well ventilated areas for charging and testing batteries.
2) Allow no smoking, sparks or open flames near batteries being
3) Do not break live electrical circuits at the terminals of batteries
PERSONAL PRECAUTIONS:
1) Wear complete protection and avoid touching eyes while
2) NEVER smoke or allow a spark or flame in the vicinity of
3) Be extra cautious to reduce risk of dropping a metal tool onto a
4) Remove personal metal items such as rings, bracelets,
5) Spilled acid: Neutralize with a solution of baking soda (1 pound
VEHICLE SAFETY:
1) Keep your body, clothing, and test leads away from all moving
2) Avoid hot engine parts.
3) Engine exhaust contains deadly carbon monoxide gas. Run
4) When running engine tests, be sure that the vehicle is in "park"
5) When disabling the ignition system to run starter tests, always
6) Do not connect any test lead to carburetor, fuel lines, or sheet
10 minutes with clear, cool water.
charged, tested or batteries recently charged or tested.
because a spark may occur at that point causing an explosion.
Always turn battery chargers or tester OFF before connecting
or disconnecting the clamps from the battery terminals.
working near battery.
battery or engine.
battery. The tool may spark or short-circuit the battery or other
electrical parts which may cause an explosion.
necklaces, and watches when working with a lead-acid battery.
A lead-acid battery can produce a short-circuit current high
enough to instantly weld a ring or the like to metal, and cause
severe burn.
per gallon of cold water) or household ammonia (1 pint per
gallon of cold water)
parts of the vehicle. Remember, electric fans may start at any
time.
engine only in a well ventilated area with exhaust gases
ventilated outdoors.
or "neutral" and the parking brake is on when starting the
vehicle. Block wheels to prevent vehicle movement.
refer to vehicle service manual for proper procedure.
metal parts of frame.
TESTER PRECAUTIONS AND NOTES:
1) Always be sure LOAD ADJUST knob is in full counter
clockwise position when disconnecting or connecting heavy
duty leads to prevent arcing.
2) Never block ventilating holes on the top or the bottom of the
unit. This will shorten the carbon pile life.
3) STEAM AND ODORS MAY BE RELEASED FROM CARBON
PILE LOAD ASSEMBLY ANYTIME IT IS USED. THE
CARBON DISCS ABSORB MOISTURE AND ODORS AS
WOULD AN ACTIVATED CARBON FILTER, THESE ARE
RELEASED WHEN THE CARBONS ARE HEATED.
4) A duty cycle is hard to define for a carbon pile load assembly.
Size of load, length of test, time between tests, ambient
temperature, and other factors affect the duty cycle. For the
longest life, never let the carbon discs get red hot. This can be
easily seen when running the load test. If the discs get red hot,
the binder material holding the carbon granules together will
start to deteriorate and lead to shortened disc life.
5) For the ammeter to read +amps, attach current probe so arrow
on probe points in direction of current flow (from positive to
negative).
6) Residual magnetism in the AMPS PICKUP may cause it to
indicate a low current even if there is no current flow. This is a
normal situation. Therefore, the AMPS meter has to be zeroed
before each use. This can be done with the AMPS ZERO
ADJUST knob.
7) In the booklet, the word "positive" refers to the red clamp or
lead. The word "negative" refers to the black clamp or lead.
8) "Positive" when referring to a battery terminal will mean the one
marked Pos, P, (+).
9) "Negative" when referring to a battery terminal will mean the
one marked Neg, N, and (-).
10) PLEASE NOTE THAT THE DEFECTIVE DIODE LIGHT MAY
FLASH ON AND OFF DURING SOME OF THE TESTS
DESCRIBED. THIS IS NORMAL AND SHOULD NOT BE
CONSTRUED TO BE A PROBLEM WITH THE UNIT.
11) During a load test, the light gauge leads may be used to read
voltage across Battery 1, cable jumper, and Battery 2. These
can be added up to give the total system voltage. This total
may not be the same as read by the voltmeter on INT position
with the clamps installed as shown. This may be caused by
corrosion on terminals, rounding off by the voltmeter circuit, or
other factors and does not mean there is a problem with the
unit.
6V
The components in the AMPS PICKUP are somewhat temperature
sensitive. As it warms near a hot engine or cools when exposed to
outdoor air, the zero on the AMPS meter may drift. Once the pickup
has stabilized, the zero will not drift.
+ -+ -
6V
BATTERY 2BATTERY 1
FIGURE 1
2
Page 3
BATTERY LOAD TESTS
TESTING 12 VOLT BATTERIES:
1) The standard battery load test is to apply a load on the battery
equal to ½ the cold cranking amp (CCA) capacity of the battery
for 15 seconds. Both the voltage and temperature of the
battery under load determine whether a battery is good or not.
2) Before testing the battery be sure that:
Battery terminals are clean.
The battery does not have any physical damage.
The battery is not frozen.
The LOAD ADJUST knob is in the full counter clockwise
position
+ -
12 VOLT
PROPER TEST PROCEDURE IS AS FOLLOWS:
1) Attach red and black heavy duty leads to the positive and
negative battery posts. Twist or rock clamps back and forth
several times to make a good connection. Be sure the VOLTS
switch is in INT position.
2) Attach the AMPS PICKUP around either lead of the tester. Be
sure the arrow points in the direction of the current flow.
3) Adjust the AMPS meter with the AMPS ZERO ADJUST knob to
give a reading of 000.
TESTING 12/24 VOLT SYSTEMS:
For best results in a 12/24 volt system that has batteries connected per the diagram above, each battery should be tested separately and the
connection between the batteries tested at the same time. Both battery tests should be run as described in the previous section.
FIGURE 2
6042
4) Read the open circuit voltage (OCV) of the battery. If the
voltage is 14.4 volts of higher, the load test may be run. If 12.3
volts or lower, (75% state of charge) the battery should be
recharged and retested.
5) Apply a load to the battery of a ½ the CCA rating for 3 seconds
to remove any surface charge. If the voltage has fallen below
12.4 volts, recharge and retest.
6) If the battery is adequately charged, apply a load to the battery
of the ½ CCA rating of the battery for 15 seconds. Adjust the
load as necessary during the test. Note the voltage of the
battery under load and then turn the load off.
The minimum acceptable voltage for a battery at the different
temperatures is as follows:
BATTERY TEMPERATURE COMPENSATION 15 SECOND
°C 21↑
°F 70↑
9.6 9.5 9.4 9.3 9.1 8.9 8.7 8.5
MIN
VLT
IF THE CCA OF THE BATTERY IS NOT KNOWN, IT CAN BE
DETERMINED BY THE FOLLOWING PROCESS:
1) Determine the temperature of the battery and find the minimum
accepted voltage from the chart above.
2) Apply a load to the battery until the voltage reaches the above
determined number.
3) Adjust the load as needed to maintain the voltage for 15
seconds. Note current at 15 seconds and turn load off.
4) Multiply the current reading by 2 to determine the CCA rating of
the battery. Check vehicle manufacturer’s recommendation for
the proper battery CCA and compare to your results.
16 10 4 -1 -7 -12 -18
60 50 40 30 20 10 0
LOAD TEST
6042
+ - + -
12V12V
BATTERY 2BATTERY 1
FRAME
FIGURE 3
PROPER TEST PROCEDURE IS AS FOLLOWS:
1) Attach heavy duty leads to Battery 1 and run battery load test.
Evaluate the results. (See figure 3)
2) Attach the negative heavy duty lead to the negative terminal of
Battery 2. Attach the positive heavy duty to the negative
terminal of Battery 1. (By attaching at that point and not at the
positive terminal of Battery 2, we will check the connection
between the batteries at the same time.) Attach the negative
light gauge voltage lead to the positive terminal of Battery 2
and the positive light gauge lead to the negative terminal of
Battery 1. (See figure 4)
3) Run the battery load test on battery 2. At the end of the 15
RED
LEAD
+ -
12V
BATTERY 1 BATTERY 2
+ -
12V
FRAME
FIGURE 4
seconds and with the load still on the battery, switch VOLTS to
EXT position and read the voltage drop across the cable
connecting the 2 batteries. Turn load off and evaluate results.
4) To evaluate the battery load test, the voltage drop read across
the cable (EXT position) has to be added to read the voltage on
the INT position to give the proper battery voltage. Evaluate
the battery based on this voltage (EXT + INT).
5) Evaluate the cable jumper between the batteries, based on the
voltage read on the EXT position. A typical acceptable voltage
drop is 0.2 volts. Check the service procedure for the vehicle if
there is any question about the acceptable voltage drop.
3
BLACK
LEAD
Page 4
USE THIS SECTION FOR BATTERY
TESTING IF YOU’RE 12/24 VOLT
SYSTEM LOOK SIMILAR TO THIS:
One six volt battery by itself cannot be tested with
this unit. It will not provide enough power under load
to allow the digital circuitry to work.
Please note: When two six volt batteries are
connected in series, the voltage of the array is 12.
The CCA rating of the series does not double. It is
the same CCA as either of the individual batteries.
(If you have two, 500 CCA, 6 volt batteries in series,
it is equivalent to a 500 CCA, 12 volt battery and
should be tested with a 250 amp load.)
Both the heavy duty and light gauge leads will be
used in this test.
1) Attach the positive heavy duty lead to the
positive terminal of Battery 1 and the negative
heavy duty lead to the negative terminal of Battery 2.
2) The light gauge leads will be used to read voltages across
Battery 1, the cable connection, and Battery 2, so the
VOLTS switch should be in the EXT position.
3) Apply the proper load to the batteries for 15 seconds. At
that time and with the load on, read the voltage of Battery
1 (red lead to positive, black lead to negative), the cable
jumper (red lead to Battery 1, negative and black lead to
Battery 2 positive), and Battery 2 (red lead to positive,
black lead to negative).
4) Turn load off and evaluate the results. Voltage drop
across the cable jumper should be 0.2 volts or less. If
there is any question, check the service manual of the
vehicle. Minimum acceptable voltage for a 6 volt battery
at different temperatures is:
BATTERY TEMPERATURE COMPENSATION 15 SECOND
°C
°F
MIN.
VOLT
Please note that the test described above is not the easiest
way to run a test on two batteries in series, but it is the most
accurate. If you were to test the batteries and take only one
voltage reading from the positive terminal of Battery 1 to the
negative terminal of Battery 2, there are problems that could
remain hidden or cause excessive replacement costs.
21↑
70↑
4.8
10
50
4.7
LOAD TEST
2
35
4.6
-4
25
4.5
-9
15
4.4
-15
4.3
+ -
+ -
BATTERY 3
5
6V
6V
+ -
6V
BATTERY 2BATTERY 1
+ -
6V
BATTERY 4
The voltage read under load from the positive terminal of
Battery 1 to the negative terminal of Battery 2 is the sum of the
voltage drops across Batteries 1, 2, and the cable jumper.
Total voltage = B1 voltage + B2 voltage + jumper voltage drop.
If you had two good batteries and a bad jumper connection, the
total voltage may be less than acceptable. If the batteries were
replaced, the new ones may test bad due to the bad
connection. Replacing or cleaning a bad jumper cable is
cheaper and easier than replacing batteries if that is all that is
needed.
In another situation, you may have one good battery, a good
jumper connection, and one bad battery. If the good battery
voltage is high enough to offset the bad battery voltage, you
will have no indication of the potential problem. If the good
battery voltage is not high enough to offset the bad battery
voltage, the group may test bad and both batteries replaced
when only one of the needs to be.
B1 VOLTAGE
RED
LEAD
JUMPER
+ -
BATTERY 1
BLACK
LEAD
B2 VOLTAGE
+ -
6V6V
BATTERY 2
FIGURE 5
FIGURE 6
TESTING 24 VOLT SYSTEMS:
24 volt batteries may be tested by the same
procedure as described for 12 volt batteries. The
minimum acceptable voltages will be twice what is
listed for 12 volt batteries.
LOAD TESTS ON 24 VOLT BATTERIES SHOULD
BE LIMITED TO 300 AMPS FOR 15 SECONDS.
Higher currents or longer times may shorten carbon
pile life.
+ -
24 VOLT
FIGURE 7
4
Page 5
STARTER TESTS
Current draw of the starter, battery voltage, and
voltage drop of leads can be measured when
connected as shown (See figure 8).
Before running any starter tests, disable the engine
by removing the coil wire from the distributor or by
FRAME
disconnecting the battery leads to the distributor
(HEI). Be sure that any leads that are removed are
insulated to prevent shorting to ground.
Review the Safety section in the front of this manual.
1) Attach the heavy duty leads to the battery as
shown. Attach the AMPS PROBE around the
lead from the positive battery terminal to the
starter. If that cable is not accessible, it may be
placed around the ground cable that runs from
the frame or engine block to the negative battery terminal.
Make sure VOLTS switch is in INT position.
2) Be sure that all the lights and accessories are turned off.
3) Crank the engine while watching both the VOLTS meter
and the AMPS meter. After 2-3 seconds of cranking, the
readings should be fairly stable. If not, continue cranking
until they are stable. Under no condition should you crank
more than 10 seconds at a time.
4) Minimum acceptable voltage for most vehicles while
cranking is 9.6 volts. Typical starting currents for vehicles
are:
4 cylinder gas engine--up to 175 amps
6 cylinder gas engine--up to 225 amps
8 cylinder gas engine--up to 250 amps
8 cylinder gas engine--up to 650 amps
The vehicle service manual should be consulted for more
detailed information. While the vehicle is cranking, you should
listen for high pitch or low growling sounds that may indicate
bearing or other problems.
Connections between the battery and starter and between the
battery and frame should also be checked at this time.
CHARGING SYSTEM TESTS
Please review all the safety instructions in the front of
this manual before running these tests.
Charging problems can be caused by a number of
different things. These can include loose belts,
defective diodes or stators, defective regulators,
corroded or loose connections or defective diode trios
(GM cars).
Undercharging will shorten battery life and may not
provide the proper charge to start the vehicle.
Overcharging will cause excess water usage in the
battery and shorten battery life.
Proper charging voltage and current from the charging
system to the battery is important for the longest life
and maximum performance.
The proper end of charge voltage will depend on the type of
battery installed by the manufacturer and ambient temperature
of the charging system.
●
A conventional battery (lead-antimony ) will require
charging voltages up to about 14.5 volts.
●
A recombination battery or low maintenance battery will
require charging voltages up to about 15.0 volts.
●
A maintenance free battery will require charging voltages
up to about 15.5 volts.
Voltage specifications will vary from manufacturer to
manufacturer. The service manual for the vehicle should be
consulted for exact charging specifications.
STARTER
SOLENOID
ALTERNATOR
ACCESSORIES
TO
STARTER
MOTOR
BLACK
LEAD
+ -
FRAME
RED
LEAD
FIGURE 8
Excessive voltage drop in either cable caused by loose or
corroded connections, undersized, or broken wires may be the
problem, not the starter.
PROPER TEST PROCEDURE IS AS FOLLOWS:
1) Attach tester to battery as shown. Switch VOLTS to EXT
position.
2) Attach positive light gauge lead to positive battery terminal.
Attach negative light gauge lead to starter solenoid where the
lead from the battery terminates.
3) Crank engine and read voltage drop of cable when readings
stabilize.
4) Repeat the same procedure, checking the voltage drop across
the solenoid, (negative lead to starter side of solenoid).
5) Repeat again, checking the voltage drop between the solenoid
and the starter. (Positive lead at solenoid, negative lead at
starter.)
6) Repeat again, checking the ground cable from the battery to
the engine block. (Positive lead to engine block, negative lead
to battery negative terminal.)
7) Acceptable voltage drop on any wire lead should be 0.2 volts or
less. Voltage drop across the starter solenoid should 0.3 volts
or less. Check vehicle service manual for further details.
FRAME
+ -
FRAME
RED
LEAD
BLACK
LEAD
FIGURE 9
It is also important that the charging system be capable of putting
out it's rated current. If the electrical load, (lights, blower, power
accessories, etc.) in the vehicle is more than the output of the
alternator, the battery will discharge to provide the needed current.
The battery may become discharged and will not recharge until
some of the load is turned off. This type of discharge/charge cycle
will greatly shorten the life of the battery. Therefore, output current
as well as output voltage of the charging system should be checked.
NOTE:
A check of the charging system should include a check of
the battery cables to ground and to the alternator to determine bad
connections.
5
Page 6
OUTPUT VOLTAGE TEST:
1) Connect tester to battery as shown. Connect AMPS PICKUP
around positive output cable of alternator. If wires split off to
feed power to accessories, the pickup must be placed over the
wires between the point the split and the alternator. Do not
place the pickup closer than 6 inches to the alternator or the
current readings may be affected by the magnetic field of the
alternator.
2) VOLTS switch should be in INT position.
3) Make sure all accessories are off in the vehicle.
4) Start vehicle and allow the engine to run at fast idle until the
current output from the alternator is between 0-10 amps. Read
the output voltage. Proper output voltages should be as listed
previously.
REMEMBER:
for ambient temperatures by increasing the charging voltage at
low temperatures. Check the vehicle service manual for proper
charging voltages at low temperatures.
Charging systems in a vehicle will compensate
OUTPUT CURRENT TEST:
Connect the tester as above and run the vehicle at fast idle. Apply a
load to the battery to obtain the highest reading on the ammeter. Do
not allow the battery voltage to drop below 12.0 volts. This ammeter
reading is the maximum output of the alternator.
GM DIODE TRIO TEST:
The diode is located inside the GM alternator and must be checked
The diode trio is located inside a GM alternator and must be
checked whenever alternator problems are suspected. These
diodes are separate from the output rectifier of the alternator. They
are used as part of a feedback loop to the internal regulator.
1) Attach the heavy gauge leads to the battery.
2) VOLTS switch should be in EXT position.
3) Attach the black light gauge lead to the negative battery post or
frame of alternator.
4) Attach the red light gauge to the number 1 terminal of the plug
in the alternator. DO NOT DISCONNECT THE PLUG FROM
THE ALTERNATOR. DAMAGE MAY RESULT IF THE PLUG
IS DISCONNECTED.
5) Start the engine and let run at normal idle. Do not apply any
load to the battery.
6) If the DEFECTIVE DIODE light comes on and stays on, it
indicates a defective diode trio. The alternator should be
repaired or replaced.
ALTERNATOR OUTPUT TEST: (Bypassing the regulator)
If the alternator did not pass the first output test that was
run, this test should be performed to determine whether
the alternator or regulator is at fault. Determine from the
vehicle service manual whether the regulator is type "A" or
"B".
1) Connect the unit to the vehicle as shown (See figure
11).
2) Disconnect the lead wire from the field terminal of the
alternator or regulator.
3) Attach the blue test lead to the field terminal of the
alternator or, if disconnected at the regulator, the
wire that leads from the regulator to the field terminal.
(IF THE LEAD FROM THE REGULATOR IS NOT
DISCONNECTED AT ONE END OR THE OTHER,
DAMAGE MAY OCCUR TO THE UNIT WHEN TESTING.)
4) Start the engine and adjust engine speed to about 2000 RPM.
5) Apply a load to the battery to reduce the system voltage by
about 2 volts.
6) Hold the spring loaded FIELD selector switch in the proper
position. In the "A" position, the field lead is connected to the
negative terminal. In the "B" position, the field lead is
connected to the positive terminal. This is called "full fielding"
the alternator. Pushing the switch into the wrong position will
not damage the alternator.
FIELD WIRE
FROM ALTERNATOR
TO REGULATOR
It should be within 10% of the manufacturer's specification to be
acceptable. If a number of accessories have been added to the
vehicle, the alternator output should be high enough to supply the
total accessory load.
OUTPUT DIODE/STATOR TEST:
1) Attach the tester as shown in the above diagram. Attach the
light gauge positive lead to the positive output terminal of the
alternator. Attach the light gauge negative lead to the frame
(ground) of the alternator. VOLTS switch should be on EXT
position.
2) Start vehicle and run at a fast idle. Apply a load to the battery
as described in the OUTPUT CURRENT TEST.
3) Defective output diodes or a stator problem will turn the
DEFECTIVE DIODE light on in 1-2 seconds and it will glow
steadily. If the light blinks on and then stays off, there are no
defective parts.
4) If the positive output terminal of the alternator is inaccessible,
the positive lead may be connected to the positive terminal of
the battery and the test run as described. The accuracy of the
test may be affected by loose or corroded terminals or an
undersized cable. Attach leads to rear of alternator if possible.
SCREWDRIVER
ALTERNATOR
PLUG
RED LEAD
TERMINAL 1
FIGURE 10
REGULATOR
F
F
ALTERNATOR
7) Adjust the lead applied to the battery to give the maximum
current reading without dropping the voltage below 12.0 volts.
8) Release the FIELD switch and turn off the load on the battery.
9) If the alternator output is not at least tested 90% of its rated
output, repair or replace the alternator. If the current reading
on the ammeter is within 10% of the manufacturer's rating, the
alternator is good and the regulator should be replaced if the
wiring to it is found to be good by these checks.
FRAME
+ -
FRAME
FIGURE 11
6
Page 7
A GM ALTERNATOR HAS A DIFFERENT PROCEDURE FOR FULL FIELDING:
1) Locate a "D" shaped hole in the rear of the alternator.
2) Insert a small screwdriver or any other metal rod in the hole
until you contact a metal tab (less than 3/4 inch). Ground the
screwdriver or rod to the case and apply a load per above
instructions.
MEASURING SMALL CURRENTS:
The BEST tester will measure currents down to one
amp in value. If smaller currents need to be
measured, follow the steps below.
TO CHECK CURRENT DRAW OF A
SPECIFIC ELECTRICAL DEVICE:
1) Attach unit to battery as shown.
2) Disconnect the power lead to the device under
test.
3) Coil the field lead of the unit 10 times around
your hand and connect the clip to the power
input terminal of the device under test.
4) Clip the AMPS PICKUP around the 10 turns of
wire.
5) Press the FIELD switch to the "B" position and
read the ammeter on the unit.
6) Divide the ammeter reading by 10 to give the
actual current draw of the device under test.
DEVICE
UNDER TEST
DISCONNECT
POWER TO DEVICE
UNDER TEST
TO CHECK CURRENT DRAW OF ENTIRE ELECTRICAL SYSTEM:
1) Disconnect the negative load from the battery.
2) Attach unit as shown (See figure 13).
3) Clip blue lead to the negative wire just removed from the
battery.
4) Wrap the blue lead around your hand 10 times and clip
AMPS PICKUP around the coil.
5) Push FIELD switch to the "A" position. Read the ammeter.
Release switch.
6) Divide ammeter reading by 10 to give the total current draw
of the vehicle from the battery.
FRAME
If the regulator is determined to be bad, check that it is making
a good ground connection to the vehicle chassis. Also, check
that the wire from the regulator to the alternator field terminal is
making good connections and does not have any breaks in it.
BLUE LEAD
(FIELD)
+ -
FRAME
+ -
6042 B.E.S.T. TESTER TROUBLE SHOOTING HINTS:
If the meter displays fail to light when the unit is connected to a
charged battery, remove the unit's cover and look at the back of the
circuit board. There are two LED's in the top middle of the board. If
both of these are lit, there is a problem on the circuit board that must
be diagnosed by a factory technician. If one LED is lit, the fuse on
the rear of the board is blown and should be replaced. Replace with
an AGC 1 fuse.
The fuse blew to protect the board against an over voltage situation
that would have damaged the solid state components on the board.
If neither LED is lit, there is no incoming power to the circuit board.
Check for good connection at the battery. Also check (with an
ohmmeter) the tracer lead in the heavy duty leads to be sure there is
a circuit from the clamp jaws to the power strip on the circuit board.
ASSEMBLY INSTRUCTIONS
Parts included with this unit are listed in the part list. Item numbers
appear on the exploded view, part list and throughout the text for
easy reference.
ITEM
QTY DESCRIPTION
1. 1 ........................................................................Lower Tray
2. 1 ........................................................................Upper Tray
3. 2 .........................................................................Back Legs
4. 20 ..................................................................¼-20x2” Bolts
5. 20 .....................................................................¼” Washers
6. 20 ................................................................¼-20 Hex Nuts
7. 2 .........................................................................Front Legs
8. 1 ...........................................................................Top Plate
9. 1 ...............................................................................Handle
10. 4 ................................................... #10x1” Machine Screws
11. 4 .................................................................10-24 Hex Nuts
12. 1 ........................................................ B.E.S.T. Control Unit
13. 4 .......................................................................Plastic Feet
14. 4 ............................................... #10x1 ¼” Machine Screws
15. 2 ...........................................................................Axle Nuts
16. 1 ...................................................................................Axle
17. 2 ..............................................................................Wheels
18. 2 ...................................................................................Feet
FIGURE 12
FRAME
BLUE LEAD
(FIELD)
FIGURE 13
PARTS LIST
7
Page 8
ASSEMBLING THE CART:
1. Place lower tray (1) and upper tra y (2) on flat surface. Align
the lower holes in back leg (3) with holes in lower tray (1),
fasten the back leg to lower tray with 2 each bolts (4), washers
(5) and nuts (6). Align the middle holes in back leg with holes
in upper tray and fasten with 2 each bolts (4), washers (5) and
nuts (6). Note: At this time only finger tighten the bolts and
nuts, so the frame can be easily adjusted to square later.
2. Place front leg (7) onto lower and upper trays aligning the holes
in all three parts. Attach the front leg to both trays with bolts
(4), washers (5) and nuts (6). Flip the cart over 180° and
repeat steps 1 and 2 for the right side legs.
See Figure 1.
4
3-1
5
6
7-1
1
2
Figure 1
3. Attach the top plate (8) and handle (9) with 4 each of #10x1”
screws (10) and #10 nuts (11).
See Figure 2.
8
11
12
14
13
Figure 3
5. Tap one axle nut (15) onto one end of the axle (16) with a
rubber mallet. Slide one wheel (17) onto the axle. Push the
axle through the holes located on the bottom of the back legs.
Slide the second wheel onto the axle. Tap the second axle nut
onto the axle.
6. Press the feet inserts (18) into the bottom of the front legs.
7. Make sure the frame is square before tightening all bolts and
nut to a snug fit.
can deform the legs.
8. Place the top plate/control unit assembly on the assembled
cart. Fasten the top plate to the back legs with 2 each bolts
(4), washers (5) and nuts (6). Attach the top plate to the front
legs. The top plate has two pairs of holes so the viewing angle
can be adjusted. Bolting through the top pair of holes will
mount the top plate in a flat position. The lower pair of holes
will elevate the plate at a 15° viewing angle.
See Figure 4
DO NOT OVER-TIGHTEN,
over-tightening
4
5
6
10
Figure 2
4. Attach the B.E.S.T. control unit (12) to the top plate (8). Place
the feet (13) between top plate and control unit. Flat side of
foot is placed against top plate. Insert the #10x1 ¼” screws
(14) through top plate and feet and thread into the threaded
fasteners in the four corners of the control unit base.
See Figure 3
.
9
17
18
15
16
Figure 4
ASSOCIATED EQUIPMENT CORPORATION
5043 Farlin Avenue Saint Louis, Missouri 63115
Tel. (314) 385-5178 Fax. (314) 385-3254
www.associatedequip.com
Z4041 027-0278 Rev. 20100204
8
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