1993 CHEVROLET PLYMOUTH ACCLAIM warning light

(2) The voltage output from each of the wheel
speed sensors is verified to be within the correct op-
erating range. If a vehicle is not set in motion within 3 minutes
from the time the ignition switch is turned to the on
position. The solenoid valve test is bypassed but the
pump/motor is activated briefly to verify that it is op-
erating correctly.
WARNING SYSTEMS OPERATION
The ABS system uses an Amber Antilock Warning
Lamp, located in the instrument cluster. The purpose
of the warning lamp is discussed in detail below. The Amber Antilock Warning Light will turn on
whenever the CAB detects a condition which results
in a shutdown of the Antilock brake system. The
Amber Antilock Warning Lamp is normally on until
the CAB completes its self tests and turns the lamp
off (approximately 1-2 seconds). When the Amber
Antilock Warning Light is on, only the Antilock
brake function of the brake system if affected. The
standard brake system and the ability to stop the car
will not be affected when only the Amber Antilock
Warning Light is on.
NORMAL OPERATION OF WARNING LAMP
With ignition key turned to the Crank position, the
Red Brake Warning Lamp and Amber Antilock
Warning Lamp will turn on as a bulb check. The
Amber Antilock Warning Lamp will stay on for 1-2
seconds then turn off, once verification of Antilock
Brake System self diagnosis is completed.
ANTILOCK BRAKE SYSTEM COMPONENTS
The following is a detailed description of the Ben-
dix Antilock 4 Brake System components. For infor-
mation on servicing the Four Wheel Disc Brake
System, see the standard Brake section in the Front
Wheel Drive Car, chassis service manual.
MODULATOR ASSEMBLY
WARNING: THE ONLY COMPONENTS OF THE
MODULATOR ASSSEMBLY THAT ARE SERVICE-
ABLE, ARE THE 2 PROPORTIONING VALVES,
BLEED SCREWS AND THREAD SAVERS. THE RE-
MAINING COMPONENTS OF THE MODULATOR AS-
SEMBLY ARE NOT INTENDED TO BE
SERVICEABLE ITEMS. NO ATTEMPT SHOULD BE
MADE TO REMOVE OR SERVICE ANY OTHER COM-
PONENTS OF THE MODEULATOR ASSEMBLY.
The Modulator Assembly (Fig. 1) is located under
the battery tray and is covered with an acid shield.
The Modulator Assembly contains the following com-
ponents for controlling the Antilock brake system. 4
Build/Decay Valves, 4 Shuttle Orifices, 2 Fluid
Sumps, 2 Accumulators, and a Pump/Motor assem- bly. Also attached to the Modulator Assembly are 6
brake tubes which are connected to a 12 way junc-
tion block. The junction block (Fig. 2) is mounted to
the left frame rail below the master cylinder in the
same location as the non ABS equipped combination
valve. The wheel brake lines are attached to the sys-
tem via the connector block.BUILD/DECAY VALVES
There are 4 Build/Decay valves, one for each
wheel. In the released position they provide a fluid
path direct to the wheel brakes. In the actuated (de-
cay) position, they provide a fluid path from the
wheel brakes to the sump. The Build/Decay valves
are spring loaded in the released (build) position.
SHUTTLE ORIFICE
There are 4 Shuttle Orifice Valves, one for each
wheel. The Shuttle Orifice Valve is a hydraulically
actuated valve which shuttles when the Build/Decay
valve is actuated. Actuating of the Build/Decay valve
causes a pressure differential to be created across the
Shuttle Orifice Valve. This acts like placing an ori-
Fig. 1 Modulator Assembly
Fig. 2 Antilock Brake Junction Block
5 - 16 ANTILOCK 4 BRAKE SYSTEM Ä

fice (restriction) in the line between the wheel and
the Build/Decay Valve. This restriction provides a
controlled build rate to each wheel brake during an
Antilock stop. The Shuttle Orifice Valve will remain
in the orificed position until the ABS cycle is com-
plete. When the ABS cycle has been completed the
Build/Decay valves will return to their released posi-
tion which will equalize the pressure across the
Shuttle Orifice Valves. When the pressure equalizes,
the spring loaded Shuttle Orifice valves will return
to the unrestricted position.
FLUID SUMPS
There are two Fluid Sumps in the Hydraulic As-
sembly, one for the primary and secondary hydraulic
circuits. The Fluid Sumps store the brake fluid that
is decayed from the wheel brakes during an ABS cy-
cle. This fluid is then pumped to an accumulator
and/or the hydraulic system in order to provide build
pressure. The typical pressure in the sumps is 50 psi,
during ABS operation only.
HYDRAULIC SPRING ACCUMULATOR
The Hydraulic Spring Accumulators (Fig. 3) (one
on each circuit) are used to store pressurized hydrau-
lic brake fluid during ABS operation only. This fluid
is used during hard braking when the ABS system is
activated, to supplement brake pressure when re-
quired. During normal Non ABS brake operation
there is NO pressurized brake fluid stored in the ac-
cumulators. The Hydraulic Spring Accumulators are
not a serviceable part of the Modulator Assembly
and should never be removed from the assembly.
PRESSURE DIFFERENTIAL SWITCH
The Pressure Differential Switch on the Bendix An-
tilock 4 Brake System is located on the frame rail
mounted brake hydraulic tube junction block. This
switch functions the same as the Pressure Differential
Switch located in the combination valve on standard
non ABS brake system. The pressure differential
switch monitors the primary and secondary hydraulic
brake circuits for a difference in pressure. A pressure
difference greater than 225 psi., will move and latch
the switch, grounding the Red Brake Warning Light
circuit. This will in turn, turn on the Red Brake
Warning Light in the instrument panel to warn the
driver of a pressure loss in one of the brake hydraulic
systems. This pressure differential switch is a replace-
able item of the junction block assembly. The Red
Brake Warning Light only indicates a problem
with the foundation brake hydraulic system and
not the Antilock system.
PUMP/MOTOR ASSEMBLY
The Modulator Assembly contains 2 Pump Assem-
blies, one each for the primary and secondary hydrau-
lic circuits. Both pumps are driven by a common
electric motor which is part of the Modulator Assembly.
The pumps take brake fluid from the sumps to supply
pressure to the accumulators or hydraulic system via
the shuttle orifice during an Antilock stop. The motor
only runs during an ABS stop and is controlled by the
CAB via the Pump/Motor Relay. The Pump/Motor
Assembly is not a serviceable item. If it requires
service the Modulator Assembly must be replaced.
PROPORTIONING VALVES
Two Proportioning Valves (Fig. 4) are used in the
Bendix Antilock 4 Brake System, one for each of the
rear wheel brake hydraulic circuits. The Proportioning
Valves function the same as in a standard brake
system. The Proportioning Valves are located on the
side of the modulator assembly (Fig. 1). Each rear
wheel hydraulic brake line, is connected to an indi-
vidual proportioning valve.
Fig. 3 Hydraulic Spring Accumulator
Fig. 4 Proportioning Valve Identification
Ä ANTILOCK 4 BRAKE SYSTEM 5 - 17

earlier in this service manual supplement. Then follow
the diagnostic procedures outlined in this section. Many conditions that generate customer complaints
may be normal operating conditions, but are judged to
be a problem due to not being familiar with the ABS
system. These conditions can be recognized without
performing extensive diagnostic work, given adequate
understanding of the operating principles and perfor-
mance characteristics of the ABS system.
DEFINITIONS
Several abbreviations are used in this manual. They
are presented here for reference.
² CABÐController Antilock Brake
² ABSÐAntilock Brake System
² PSIÐPounds per Square Inch (pressure)
² WSSÐWheel Speed Sensor
² ACÐAlternating Current
ABS COMPUTER SYSTEM SERVICE PRECAUTIONS
The ABS system uses an electronic control module,
the CAB. This module is designed to withstand normal
current draws associated with vehicle operation. How-
ever care must be taken to avoid overloading the CAB
circuits. In testing for open or short circuits, do
not ground or apply voltage to any of the circuits
unless instructed to do so by the appropriate
diagnostic procedure. These circuits should only be
tested using a high impedance multi-meter, special
tools or the DRB II tester as described in this section.
Power should never be removed or applied to any
control module with the ignition in the ON position.
Before removing or connecting battery cables, fuses, or
connectors, always turn the ignition to the OFF posi-
tion.
ABS GENERAL SERVICE PRECAUTIONS
TEST DRIVING ABS COMPLAINT VEHICLES
Most ABS complaints will require a test drive as a
part of the diagnostic procedure. The purpose of the
test drive is to duplicate the condition. Remember conditions that result in the turn-
ing on of the Red Brake Warning Lamp may
indicate reduced braking ability. The following
procedure should be used to test drive an ABS
complaint vehicle. Before test driving a brake complaint vehicle, note
whether the Red or Amber Brake Warning Lamp is
turned on. If the Red Brake Warning Lamp, is
turned on, refer to the base brake Control Valves
Section in the Front Wheel Drive, chassis service
manual. If the Amber Antilock Warning light was or
is on, read record and erase the faults. While the
Amber ABS Warning Lamp is on the ABS system is
not functional. The standard brake system and abil- ity to stop the car is not affected, if only the Amber
Antilock Warning Lamp is on.
(1) Turn ignition key to the off position and then
back to the on position. Note whether the Amber ABS
Warning Lamp continues to stay on. If it does refer to
the 1994 Bendix Antilock 4 Brake System Diagnostic
Manual for the required diagnostic test procedures. (2) If the Amber ABS Warning Lamp goes out, shift
vehicle into gear and drive car to a speed of 5 mph to
complete the ABS drive-off cycle. If at this time, the
Amber ABS Warning Lamp goes on refer to the 1994
Bendix Antilock 4 Brake System Diagnostic Manual. (3) If the Amber ABS Warning Lamp remains OUT,
continue to drive the vehicle a short distance. During
this test drive be sure that the vehicle achieves at least
25 mph. Brake to at least one complete stop and again
accelerate to 25 mph. (4) If a functional problem with the ABS system is
determined while test driving a vehicle. Refer to the
Bendix Antilock 4 Brake System Diagnostics Manual
for required diagnostic test procedures and proper use
of the DRB II tester.
ABS BRAKE SYSTEM ON VEHICLE SERVICE
The following are general precautions which
should be observed whenever servicing and or
diagnosing the ABS system and other vehicle
electronic systems. Failure to observe these pre-
cautions may result in ABS system damage. (1) If welding work is to be performed on a vehicle
using an arc welder. The wiring harness connector
should be disconnected from the CAB before beginning
any welding operation. (2) The CAB 60 way connector and modulator as-
sembly 10 way connector, should never be connected or
disconnected with the ignition in the on position. (3) Some components of Bendix Antilock 4 Brake
System assemblies can not be serviced separately from
the assembly and will require replacement of the
complete assembly for servicing. Do not disassemble
any component which is designated as non-serviceable.
CAUTION: Brake fluid will damage painted surfaces.
If brake fluid is spilled on any painted surfaces, wash
off with water immediately.
WHEEL SPEED SENSOR CABLES
Proper installation and routing of the Wheel Speed
Sensor Cables is critical to continued system opera-
tion. Be sure that cables are installed, routed and
clipped properly. Failure to install speed sensor ca-
bles as shown in the on car service section of this
Ä ANTILOCK 4 BRAKE SYSTEM 5 - 23

manual. May result in contact with moving parts or
over extension of cables, resulting in component fail-
ure and an open circuit.
MECHANICAL DIAGNOSTICS AND SERVICE
PROCEDURES
SPECIAL SERVICE TOOL
Some diagnostic procedures in this section require
the use of the DRB diagnostics tester. The proper ap-
plication and procedures for the use of this tool are
described below.
DRB DIAGNOSTIC TESTER
Some of the diagnostic procedures that are ex-
plained in this section require the use of the DRB Di-
agnostics Tester to insure that proper diagnostics are
performed. Refer to those sections for proper testing
procedures and the DRB operators manual for its
proper operational information.
INTERMITTENT FAULTS
As with virtually any electronic system, intermit-
tent faults in the ABS system may be difficult to ac-
curately diagnose. Most intermittent faults are caused by faulty elec-
trical connections or wiring. When an intermittent
fault is encountered, check suspect circuits for: (1) Poor mating of wiring harness connector halves
or terminals not fully seated in the connector body. (2) Improperly formed or damaged terminals. All
connector terminals in a suspect circuit should be
checked and carefully reformed to increase contact
tension with its mating terminal. (3) Poor terminal to wire connection. This requires
removing the terminal from the connector body to in-
spect. (4) Pin presence in the connector assembly
(5) Connector push-in, spread, and corrosion.
If a visual check does not find the cause of the
problem, operate the car in an attempt to duplicate
the condition and record the set Fault code. Most failures of the ABS system will disable the
Antilock function for the entire ignition cycle even if
the fault clears before key-off. There are some failure
conditions, however, which will allow ABS operation
to resume during the ignition cycle in which it oc-
curred, if the failure condition is no longer present.
The following conditions may result in intermittent
illumination of the Amber Antilock Warning Lamp.
All other failures will cause the lamp to remain on
until the ignition switch is turned off. Circuits in-
volving these inputs to the CAB should be investi-
gated if a complaint of intermittent warning system
operation is encountered. (1) Low system voltage: If Low System Voltage is
detected by the CAB, the CAB will turn on the Am-
ber Antilock Warning Lamp until normal system voltage is achieved. Once normal voltage is seen at
the CAB, normal operation resumes.
(2) Antilock system and pump/motor relay. If the
relays fail to make the ground circuit connection or
has an intermittent ground. The CAB will turn on
the Amber Antilock Warning Light. (3) Excess decay, an extended pressure decay pe-
riod, will turn on the Amber Antilock Warning Light
until the vehicle comes to a complete stop. Additionally, any condition which results in inter-
ruption of electrical current to the CAB or modulator
assembly, may cause the Amber Antilock Warning
Lamp to turn on intermittently.
ABS BRAKE SYSTEM DIAGNOSTIC FEATURES
ABS SYSTEM SELF DIAGNOSIS
The ABS system is equipped with a self diagnostic
capability which may be used to assist in isolation of
ABS faults. The features of the self diagnostics sys-
tem are described below.
START-UP CYCLE
The self diagnostic ABS start up cycle begins when
the ignition switch is turned to the on position. An
electrical check is completed on the ABS components.
Such as Wheel Speed Sensor Continuity and System
and other Relay continuity. During this check the
Amber Antilock Light is turned on for approximately
1- 2 seconds. Further Functional testing is accomplished once
the vehicle is set in motion, known as drive-off.
² The solenoid valves and the pump/motor are acti-
vated briefly to verify function.
² The voltage output from the wheel speed sensors is
verified to be within the correct operating range. If the vehicle is not set in motion within 3 minutes
from the time the ignition switch is set in the on po-
sition. The solenoid test is bypassed but the pump/
motor is activated briefly to verify that it is
operating correctly.
CONTROLLER ANTILOCK BRAKE CAB
Fault codes are kept in a Non-Volatile memory un-
til either erased by the technician using the DRB or
erased automatically after 50 ignition cycles (key
ON-OFF cycles). The only fault that will not be
erased after 50 (KEY CYCLES) is the CAB fault. A
CAB fault can only be erased by the technician using
the DRB diagnostic tester. More than one fault can
be stored at a time. The number of key cycles since
the most recent fault was stored is also displayed.
Most functions of the CAB and ABS system can be
accessed by the technician for testing and diagnostic
purposes by using the DRB.
5 - 24 ANTILOCK 4 BRAKE SYSTEM Ä

LATCHING VERSUS NON-LATCHING ABS FAULTS
Some faults detected by the CAB are latching; the
fault is latched and ABS is disabled until the igni-
tion switch is reset. Thus ABS is disabled even if the
original fault has disappeared. Other faults are non-
latching; any warning lights that are turned on, are
only turned on as long as the fault condition exists.
As soon as the condition goes away, the Antilock
Warning Light is turned off. Although a fault code
will be set in most cases.
BENDIX ANTILOCK 4 BRAKE SYSTEM DIAGNOSTICS
Bendix Antilock 4 Brake System Diagnostics, be-
yond basic mechanical diagnostics, covered earlier in
this section, are accomplished by using the DRB scan
tool. See testing procedures outlined in the 1994 Ben-
dix Antilock 4 Diagnostics Manual. Please refer to the above mentioned manual for
any further electronic diagnostics and service proce-
dures that are required on the Bendix Antilock 4
Brake System.
ON-CAR ABS BRAKE SYSTEM SERVICE
GENERAL SERVICE PRECAUTIONS
The following are general cautions which should be
observed when servicing the Bendix Antilock 4
Brake System and other vehicle electronic systems.
Failure to observe these precautions may result in
Antilock Brake System component damage. If welding work is to be performed on a vehicle us-
ing an electric arc welder, disconnect the 60 way wir-
ing harness connector from the CAB, prior to
performing the welding operation. The wiring harness connector should never be con-
nected or disconnected from the CAB with the igni-
tion key in the ON or Run position. (3) Most components making up the assemblies of
the Bendix Antilock 4 Brake System can not be ser-
viced separately from those assemblies. This will re-
quire replacement of the complete assembly for the
servicing of these components. Do not disassemble
any component from an assembly which is desig-
nated as non-serviceable.
CHECKING BRAKE FLUID LEVEL
CAUTION: Only use brake fluid conforming to DOT
3 specifications, such as Mopar or Equivalent. Do
not use any fluid which contains a petroleum base.
Do not use a container which has been used for pe-
troleum based fluids or a container which is wet
with water. Petroleum based fluids will cause swell-
ing and distortion of rubber parts in the hydraulic
brake system. Water will mix with brake fluid, low-
ering the boiling point of the brake fluid, possibly causing brake fluid to boil resulting in brake fade.
Keep all brake fluid containers capped to prevent
contamination. Remove the front cap of the master
cylinder reservoir and fill to the bottom of the split
ring.
For the specific procedure for the inspection of
brake fluid level and adding of brake to the reser-
voir. Refer to the Service Adjustments Section in this
group of the service manual.
BLEEDING BENDIX ANTILOCK 4 BRAKE SYSTEM
The base brakes and Antilock Brake System must
be bled anytime air is permitted to enter the hydrau-
lic system, due to disconnection of brake lines, hoses
or components. If the Antilock Modulator Assembly is removed
from the vehicle, both the Base Brake System and
the Antilock Brake System must be bled using the
appropriate procedure. It is important to note that
excessive air in the brake system will cause a soft or
spongy feeling brake pedal. During brake bleeding operations, ensure that
brake fluid level remains close to the FULL level in
the reservoir. Check brake fluid level periodically
during bleeding procedure, adding DOT 3 brake fluid
as required.
CAUTION: The base brake and Antilock brake hy-
draulic systems, on the Bendix Antilock 4 Brake
System, can NOT be bled using any type of brake
pressure bleeding equipment. This type of bleeding
equipment does not develop the pressure required
in the brake hydraulic system, to adequately bleed
all trapped air. The only approved method for bleed-
ing air out of the hydraulic system on vehicles
equipped with the Bendix Antilock 4 Brake System,
is the manual procedure of pressurizing the hydrau-
lic system using constant, moderate to heavy foot
pressure on the brake pedal.
The Bendix Antilock 4 Brake System must be bled
as two independent brake systems. The non ABS por-
tion of the brake system is to be bled the same as
any non ABS system. Refer to the Service Adjust-
ments section in this manual for the proper bleeding
procedure to be used. The Bendix Antilock 4 Brake
System can only be bled using a manual method of
pressurizing the brakes hydraulic system. The Antilock portion of brake system MUST be
bled separately. This bleeding procedure requires the
use of the DRB Diagnostic tester and the bleeding se-
quence procedure outlined below.
Ä ANTILOCK 4 BRAKE SYSTEM 5 - 25

RADIATOR PRESSURE CAP
Radiators are equipped with a pressure cap which
releases pressure at some point within a range of
97-124 kPa (14-18 psi) (Fig. 7). The system will operate at higher than atmospheric
pressure which raises the coolant boiling point allow-
ing increased radiator cooling capacity. There is also a vent valve in the center of the cap that
allows a small coolant flow to the CRS tank. If valve is
stuck shut, the radiator hoses will be collapsed
on cool down. Clean the vent valve (Fig. 7) to
ensure proper sealing when boiling point is
reached.
There is also a gasket in the cap to seal to the top of
the filler neck so that vacuum can be maintained for
drawing coolant back into the radiator from the coolant
reserve system tank.
RADIATOR CAP TO FILLER NECK SEAL PRES- SURE RELIEF CHECK
The pressure cap upper gasket (seal) pressure relief
can be checked by removing the overflow hose at the
radiator filler neck nipple (Fig. 7). Attach the Radiator
Pressure Tool to the filler neck nipple and pump air
into the radiator. Pressure cap upper gasket should
relieve at 69-124 kPa (10-18 psi) and hold pressure at
55 kPa (8 psi) minimum.
WARNING: THE WARNING WORDS DO NOT OPEN
HOT ON THE RADIATOR PRESSURE CAP IS A
SAFETY PRECAUTION. WHEN HOT, PRESSURE
BUILDS UP IN COOLING SYSTEM. TO PREVENT
SCALDING OR INJURY, THE RADIATOR CAP
SHOULD NOT BE REMOVED WHILE THE SYSTEM IS
HOT AND/OR UNDER PRESSURE.
There is no need to remove the radiator cap at any
time except for the following purposes:
(1) Check and adjust antifreeze freeze point.
(2) Refill system with new antifreeze.
(3) Conducting service procedures.
(4) Checking for vacuum leaks.
WARNING: IF VEHICLE HAS BEEN RUN RECENTLY,
WAIT 15 MINUTES BEFORE REMOVING CAP. THEN PLACE A SHOP TOWEL OVER THE CAP AND WITH-
OUT PUSHING DOWN ROTATE IT COUNTER-
CLOCKWISE TO THE FIRST STOP. ALLOW FLUIDS
TO ESCAPE THROUGH THE OVERFLOW TUBE AND
WHEN THE SYSTEM STOPS PUSHING COOLANT
AND STEAM INTO THE CRS TANK AND PRESSURE
DROPS PUSH DOWN AND REMOVE THE CAP COM-
PLETELY. SQUEEZING THE RADIATOR INLET HOSE
WITH A SHOP TOWEL (TO CHECK PRESSURE) BE-
FORE AND AFTER TURNING TO THE FIRST STOP IS
RECOMMENDED.
PRESSURE TESTING RADIATOR CAPS
Dip the pressure cap in water, clean any deposits off
the vent valve or its seat and apply cap to end of
Radiator Pressure Tool. Working the plunger, bring the
pressure to 104 kPa (15 psi) on the gauge. If the
pressure cap fails to hold pressure of at least 97 kPa
(14 psi) replace cap. See CAUTION
If the pressure cap tests properly while positioned on
Radiator Pressure Tool, but will not hold pressure or
vacuum when positioned on the radiator. Inspect the
radiator filler neck and cap top gasket for irregularities
that may prevent the cap from sealing properly.
CAUTION: Radiator Pressure Tool is very sensitive to
small air leaks which will not cause cooling system
problems. A pressure cap that does not have a
history of coolant loss should not be replaced just
because it leaks slowly when tested with this tool.
Add water to the tool. Turn tool upside down and
recheck pressure cap to confirm that cap is bad.
INSPECTION
Hold the cap in hand, right side up(Fig. 7). The
vent valve at the bottom of the cap should open. If the
rubber gasket has swollen and prevents the valve from
opening, replace the cap. Hold the cleaned cap in hand upside down.If any
light can be seen between vent valve and rubber
gasket, replace cap. Do not use a replacement cap
that has a spring to hold the vent shut. Replacement cap must be of the type designed for
coolant reserve systems. This design assures coolant
return to radiator.
RADIATORS
The radiators are crossflow types (horizontal tubes)
with design features that provide greater strength as
well as sufficient heat transfer capabilities to keep the
engine satisfactorily cooled.
CAUTION: Plastic tanks, while stronger then brass
are subject to damage by impact, such as wrenches.
Fig. 7 Radiator Pressure Cap Filler Neck
7 - 18 COOLING SYSTEM Ä

It is important when using the Test Indicator that
the battery be level and have a clean top to see the
correct indications. A light may be required to view
the Indicator.
WARNING: DO NOT USE OPEN FLAME NEAR BAT-
TERY BECAUSE OF EXPLOSIVE GASES AT FORM
ABOVE BATTERY.
STATE OF CHARGE TESTS
USING TEST INDICATOR
The built in test hydrometer (Figs. 3, 4 and 5) mea-
sures the specific gravity of the electrolyte. Specific
Gravity (SG) of the electrolyte will show state of
charge voltage. The test indicator WILL NOT show
cranking capacity of the battery. Refer to Battery
Load. Look into the sight glass (Figs. 4 and 5) and
note the color of the indicator (Fig. 5). Refer to the
following description of colors:
² GREEN = 75 to 100 degree state of charge
The battery is adequately charged for further test-
ing and may be returned to use. If the vehicle will
not crank for a maximum 15 seconds, refer to Bat-
tery Load Test in this Group for more information.
² BLACK OR DAR K=0to75degree state of
charge The battery is INADEQUATELY charged and
must be charged until green dot is visible, (12.4 volts
or greater) before the battery is tested or returned to
use. Refer to Causes of Battery Discharging.
² YELLOW OR BRIGHT COLOR = Battery must
be replace
WARNING: DO NOT CHARGE, ASSIST BOOST,
LOAD TEST, OR ADD WATER TO THE BATTERY
WHEN YELLOW OR BRIGHT COLOR DOT IS VISI-
BLE. PERSONAL INJURY MAY OCCUR.
A yellow or bright color dot shows electrolyte level
in battery is below the test indicator (Fig. 5). Water
cannot be added to a maintenance free battery. The
battery must be replaced. A low electrolyte level may
be caused by an over charging condition. Refer to
Generator Test Procedures on Vehicle.
CAUSES OF BATTERY DISCHARGING
It is normal to have a small 5 to 30 milliamperes
continuous electrical draw from the battery. This
draw will take place with the ignition in the OFF po-
sition, and the courtesy, dome, storage compart-
ments, and engine compartment lights OFF. The
continuous draw is due to various electronic features
or accessories that require electrical current with the
ignition OFF to function properly. When a vehicle is
not used over an extended period approximately 20
days the Main Fusible Link Connector (Fig. 6)
should be disconnected. This is located near the bat- tery on the engine wiring harness. Disconnection of
this connector will help prevent battery discharging.
Refer to Fig. 7 for Battery Diagnostics.
ABNORMAL BATTERY DISCHARGING
(1) Corroded battery posts, cables or terminals.
(2) Loose or worn generator drive belt.
(3) Electrical loads that exceed the output of the
charging system due to equipment or accessories in-
stalled after delivery. (4) Slow driving speeds in heavy traffic conditions
or prolonged idling with high-amperage electrical
systems in use. (5) Defective electrical circuit or component caus-
ing excess Ignition Off Draw (IOD). Refer to Ignition
OFF Draw (IOD). (6) Defective charging system.
(7) Defective battery.
BATTERY OPEN CIRCUIT VOLTAGE TEST
An open circuit voltage, no load test will show the
state of charge in a battery. Also, if it will pass a
load test of 50 percent of the battery cold crank rat-
ing. Refer to Battery Load Test. If a battery has an
open circuit voltage reading of 12.4 volts or greater,
and will not pass a load test, it is defective and re-
placement would be required. To test open circuit
voltage, perform the following operation: (1) Remove both battery cables, negative first. If
the battery has been boosted, charged, or loaded just
prior to this operation, allow the battery a few min-
utes to stabilize. (2) Using a voltmeter connected to the battery
posts and measure the open circuit voltage (Fig. 8).
Fig. 6 Main Fusible Link Connector
8A - 4 BATTERY/STARTING/CHARGING SYSTEMS DIAGNOSTICS Ä

After 15 seconds, record the loaded voltage reading
and return the load control to the off position. (6) Voltage drop will vary according to battery
temperature at the time of the load test. Battery
temperature can be estimated by the temperature of
exposure over the preceding several hours. If the bat-
tery has been charged, boosted, or loaded a few min-
utes prior to the test, the battery would be slightly
warmer. Refer to Fig. 14 for proper loaded voltage
reading.
(7) If battery passes load test, it is in good condi-
tion and further tests are not necessary. If it fails
load test, it should be replaced.
BATTERY CHARGING
A battery is considered fully charged when it will
meet all the following requirements:
² It has an open circuit voltage charge of at least
12.4 volts (Fig. 9)
² It passes the 15 second load test (Fig. 14)
² The built in test indicator dot is GREEN (Fig. 5)
² The battery cannot be refilled with water. It must
be replaced WARNING: DO NOT CHARGE A BATTERY THAT
HAS EXCESSIVELY LOW ELECTROLYTE LEVEL.
BATTERY MAY SPARK INTERNALLY AND EX-
PLODE. EXPLOSIVE GASES FORM OVER THE BATTERY.
DO NOT SMOKE, USE FLAME, OR CREATE
SPARKS NEAR BATTERY. DO NOT ASSIST BOOST OR CHARGE A FROZEN
BATTERY. BATTERY CASING MAY FRACTURE. BATTERY ACID IS POISON, AND MAY CAUSE SE-
VERE BURNS AND THE BATTERY CONTAIN SUL-
FURIC ACID. AVOID CONTACT WITH SKIN, EYES,
OR CLOTHING. IN THE EVENT OF CONTACT,
FLUSH WITH WATER AND CALL PHYSICIAN IMME-
DIATELY. KEEP OUT OF REACH OF CHILDREN.
CAUTION: Disconnect the battery negative cable
first (Fig. 15) before charging battery to avoid dam-
age to electrical systems. Do not exceed 16.0 volts
while charging battery. Refer to the instructions
supplied with charging equipment
Battery electrolyte will bubble inside the battery
case while being charged properly. If the electrolyte
boils violently, or is discharged from the vent holes
while charging, immediately reduce charging rate or
turn off charger. Evaluate battery condition. Battery
damage may occur if charging is excessive. Some battery chargers are equipped with polarity
sensing devices to protect the charger or battery from
being damaged if improperly connected. If the bat-
tery state of charge is too low for the polarity sensor
to detect, the sensor must be bypassed for charger to
operate. Refer to operating instructions provided
with battery charger being used.
CAUTION: Charge battery until test indicator ap-
pears green. Do not overcharge.
It may be necessary to jiggle the battery or vehicle
to bring the green dot (in the test indicator) into
view. After the battery has been charged to 12.4 volts or
greater, perform a load test to decide cranking capac-
Fig. 13 Load 50 Percent Cold Crank Rating
Fig. 14 Load Test Temperature
Fig. 15 Disconnect Negative Battery Cable
Ä BATTERY/STARTING/CHARGING SYSTEMS DIAGNOSTICS 8A - 7