key CHEVROLET DYNASTY 1993 User Guide

(11) Remove all special tools previously installed,
from the ABS hydraulic assembly. (12) Install accumulator port plug into hydraulic
assembly. Torque accumulator port plug to 12 N Im(9
ft. lbs.). (13) Install high pressure brake hose from the
pump motor assembly into hydraulic fitting on ABS
hydraulic assembly. Torque high pressure brake hose
tube nut to 16 N Im (145 in. lbs.).
(14) Turn ignition switch to the run position to en-
ergize the pump/motor assembly and pressurize hy-
draulic system. Check for leakage at the hydraulic
assembly to hydraulic bladder accumulator fitting. (15) Again de-pressurize accumulator by pumping
brake pedal a minimum of 40 times. Use procedure
described in De-Pressurizing Hydraulic Accumulator
in this section of the service manual. (16) Then check the brake fluid level in the hy-
draulic assembly reservoir. If brake fluid level is low,
fill reservoir to proper level with Mopar tbrake fluid
or equivalent conforming to DOT 3 requirements.
INTERMITTENT FAULTS
As with almost any electronic system, intermittent
faults in the ABS system may be difficult to accu-
rately 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 electrical connector halves, or
electrical terminals not fully seated in the connector
body. (2) Improperly formed or damaged electrical termi-
nals. All connector terminals in a suspect circuit
should be carefully reformed to increase contact ten-
sion. (3) Poor terminal to wire connection. This requires
removing the terminal from the connector body and
inspecting for proper terminal to wire connection. If a visual check does not find the cause of the
problem, operate the vehicle in an attempt to dupli-
cate the condition and record the Fault Code. Most failures of the ABS system will disable the
Anti-Lock function for the entire ignition cycle even
if the fault clears before ignition key-off. There are
some failure conditions however, which will allow
ABS operation to resume during the ignition cycle in
which a failure occurred. If the failure conditions are
no longer present. The following conditions may result in intermittent
illumination of the Red Brake Warning Lamp and/or
Amber Anti-Lock Warning Lamp. All other failures
will cause the lamp(s) to remain on until the ignition
switch is turned off. Circuits and or components in-
volving these inputs to the (CAB) should be investi-
gated if a complaint of intermittent warning system
operation is encountered. ²
Low system voltage. If low system voltage is de-
tected by the (CAB), the (CAB) will turn on the Am-
ber Anti-Lock Warning Lamp until normal system
voltage is achieved. Once normal voltage is seen at
the (CAB), normal operation resumes.
² Low Brake Fluid. A low brake fluid condition will
cause the Red Brake Warning Lamp to illuminate.
When the fluid sensor again indicates an acceptable
fluid level, the Red Brake Warning Lamp will go out.
This condition may exist during hard cornering or
while the vehicle is on a grade. If the vehicle is in
motion above 3 M.P.H. the Amber Anti-Lock Warn-
ing Lamp will also be turned on.
² Low Accumulator Pressure. Low Accumulator
Pressure will cause both the Red Brake Warning and
Amber Anti-Lock Warning Lamps to illuminate.
Once normal operating pressure is achieved, the
lamps will extinguish and the system will return to
normal operation. Additionally, any condition that results in an inter-
ruption of power to the (CAB) or hydraulic assembly.
May cause the Red Brake Warning and Amber Anti-
Lock Warning Lamps to illuminate intermittently. All the conditions (or faults) mentioned above, can
store a fault code in the (CAB) module.
ABS BRAKE SYSTEM DIAGNOSTIC FEATURES
SYSTEM SELF DIAGNOSIS
The ABS system is equipped with a diagnostic ca-
pability that may be used to assist in isolation of
ABS faults. The features of the diagnostics system
are described below.
CONTROLLER ANTI-LOCK BRAKE (CAB)
Fault codes are kept in a Non-Volatile memory un-
til either erased by the technician using the DRB II
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.
The (CAB) fault can only be erased by using the
DRB II 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 ac-
cessed by the technician for testing and diagnostic
purposes by using the DRB II Diagnostic Tester.
START-UP CYCLE
The START-UP CYCLE takes place immediately
after the ignition switch is turned on. It is an elec-
trical check of basic electrical functions such as the
System Relay and Anti-Lock Warning Lamp Relay.
During this check, the Amber Anti-Lock Warning
Lamp is turned on, then turned off at the end of the
test. The test takes approximatel y1-2seconds to
complete.
5 - 92 ANTI-LOCK 10 BRAKE SYSTEM Ä

In order to effectively diagnose an Anti-Lock Brake
System (ABS) condition. It is important to read Anti-
Lock Brake System Description. And to 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. See Section 1
of this manual to familiarize yourself with the operat-
ing principles of the ABS system.
DEFINITIONS
Several abbreviations are used in this manual. They
are presented here for reference.
² CABÐController Anti-Lock Brake
² ABSÐAnti-Lock Brake System
² PSIÐPounds per Square Inch (pressure)
² WSSÐWheel Speed Sensor
ABS COMPUTER SYSTEM SERVICE PRECAUTIONS
The ABS system uses an electronic control module,
the (CAB). This module is designed to withstand nor-
mal current draws associated with vehicle operation.
However 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 appro-
priate 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 posi-
tion. Before removing or connecting battery cables,
fuses, or connectors, always turn the ignition to the
OFF position.
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 it is the Red Brake Warning Lamp, refer
to the standard brake, Control Valves Section in the
brake group of this manual. If the Amber Anti-Lock
Warning light was/is on, read record and erase the
fault. While the Amber ABS Warning Lamp is on the
ABS system is not functional. When the Am- ber Anti-Lock Warning Lamp is on only the Anti-Lock
function of the brake system if affected. The standard
brake system and the ability to stop the car is not be
affected if only the Amber Anti-Lock Warning Lamp is
on. (1) Turn the 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 1993
M.Y. Bendix Anti-Lock 6 Diagnostic Manual for the
required test procedures. (2) If the Amber ABS Warning Lamp goes out, shift
into gear and drive the car to a speed of 5 mph to
complete the ABS start up cycle. If at this time the
Amber ABS Warning Lamp goes on refer to the Bendix
Anti-Lock 6 Diagnostic Manual. (3) If the Amber ABS Warning Lamp remains OUT,
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 acceler-
ate to 25 mph. (4) If a functional problem with the A.B.S. system is
determined while test driving a vehicle. Refer to the
Bendix Anti-Lock 6 Diagnostics Manual for required
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 when servicing and diagnos-
ing the ABS system and/or other vehicle systems.
Failure to observe these precautions may result
in ABS system damage. (1) If welding work is to be performed on a vehicle
using an arc welder, the (CAB) should be disconnected
before the welding operation begins. (2) The (CAB) and modulator assembly 10 way con-
nector should never be connected or disconnected with
the ignition in the on position. (3) Some components of the ABS system are not
serviced separately and must be serviced as complete
assemblies. 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 of the Wheel Speed Sensor Cables
is critical to continued system operation. Be sure that
cables are installed, routed and clipped properly. Fail-
ure to install speed sensor cables as shown in the on
car service section of this manual. May result in
contact with moving parts or over extension of cables,
resulting in component failure and an open circuit.
5 - 124 ANTI-LOCK 6 BRAKE SYSTEM Ä

MECHANICAL DIAGNOSTICS AND SERVICE
PROCEDURES
SPECIAL SERVICE TOOL
Some diagnostic procedures in this section require
the use of the DRB II diagnostics tester. The proper
application and procedures for the use of this tool are
described below.
DRB II DIAGNOSTIC TESTER Some of the diagnostic procedures that are ex-
plained in this section require the use of the DRB II
Diagnostics Tester to insure that proper diagnostics
are performed. Refer to those sections for proper test-
ing procedures and the DRB II 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 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
carefully reformed to increase contact tension. (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
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 Fault code. Most failures of the ABS system will disable Anti-
Lock 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 a fail-
ure occurred. If the failure conditions are no longer
present. The following conditions may result in inter-
mittent illumination of the Amber Anti-Lock Warn-
ing Lamp. All other failures will cause the lamp to
remain on until the ignition switch is turned off. Cir-
cuits involving these inputs to the (CAB) should be
investigated 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
Amber Anti-Lock Warning Lamp until normal sys-
tem voltage is achieved. Once normal voltage is seen
at the (CAB), normal operation resumes. (2) Anti-Lock relay. If the relay fails to make the
ground circuit connection or is an intermittent
ground. The (CAB) will turn on the Amber Anti-Lock
Warning Light. (3) Excess decay, an extended pressure decay pe-
riod, will turn on the Amber Anti-Lock 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 modula-
tor assembly. May cause the Amber Anti-Lock
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 Anti-Lock Light is turned on for approxi-
mately 1- 2 seconds. Further Functional testing is accomplished once
the vehicle is set in motion.
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 ANTI-LOCK BRAKE (CAB)
Fault codes are kept in a Non-Volatile memory un-
til either erased by the technician using the DRB II
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 us-
ing the DRB II 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 dis-
played. Most functions of the (CAB) and ABS system
can be accessed by the technician for testing and di-
agnostic purposes by using the DRB II.
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.
Ä ANTI-LOCK 6 BRAKE SYSTEM 5 - 125

The instrument panel bulb can be checked each
time the ignition switch is turned to the start posi-
tion or the parking brake is set.
HYDRAULIC SYSTEM SERVICE PROCEDURES
BRAKE WARNING SYSTEM
CHECKING BRAKE WARNING SWITCH UNIT
The Red Brake Warning light will come on when the
parking brake is applied with the ignition key turned
ON. The same light will also illuminate should one of
the two service brake hydraulic systems fail.
CAUTION:Make sure air does not enter the hydraulic
system during this test procedure. See bleeding with-
out a pressure bleeder at the beginning of this section
for master cylinder fluid level checking procedures.
To test the service brake warning system lamp.
Raise vehicle on a hoist and open a wheel cylinder
bleeder while a helper depresses the brake pedal and
observes the warning light.
If light fails to come on, inspect for a burned out bulb,
disconnected socket, or a broken or disconnected wire at
the switch. If the bulb is not burned out and the wire
continuity is not interrupted. Check the service brake
warning switch operation with a test lamp between the
switch terminal and a known good ground. Be sure to
fill master cylinder and bleed brake system after correc-
tion has been made, if necessary.
TESTING ANTILOCK PROPORTIONING VALVES
(1) Install one gauge and (TEE) between modula-
tor assembly and male end (Inlet) of proportioning
valve (Fig. 4). (2) Install second gauge at female end (Outlet) of
proportioning valve (Fig. 4).
(3) Have a helper exert pressure on brake pedal to
obtain and hold required pressure reading on the
valve inlet gauge. (4) Check reading on outlet gauge. If inlet and out-
let pressures do not agree with the following chart,
replace the valve. See (Fig. 3) for proportioning valve
identification.
BENDIX ANTILOCK 4 PROPORTIONING VALVE APPLICATIONS
BENDIX ANTILOCK 4 PROPORTIONING VALVE PRESSURES
Fig. 4 Tube Connections for ABS
Ä BRAKES 5 - 11

(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

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

CLUTCH PEDAL POSITION SWITCH
The clutch pedal position switch functions as a
safety interlock device. It prevents possible engine
cranking with the clutch engaged. The clutch pedal position switch is wired in series
between the starter relay coil and the ignition
switch. The clutch pedal position switch is mounted to a
bracket located next to the clutch pedal. The switch
is held in place by four plastic wing tabs. The clutch pedal position switch has an adjustable
striker plate. The striker plate is located on the left
side of the clutch pedal (Fig. 3).
DIAGNOSIS
Disconnect clutch pedal position switch harness
from instrument panel wiring harness. Using a ohm
meter, check for continuity between the two termi-
nals in the connector on the switch harness. There
should be no continuity between the terminals when
the switch is in its neutral (fully extended) position.
When the switch is depressed more than 1.25 mm
(0.050) the ohm meter should show continuity. If all ohm meter readings are correct and the
switch does not operate correctly, adjustment is re-
quired. Refer to Switch Adjustment Procedure to ad-
just switch.
REMOVAL
(1) Disconnect electrical harness to switch connec-
tor. (2) Depress wing tabs on switch and push switch out
of mounting bracket. Then slide wires through slot in
bracket.
INSTALLATION
(1) Slide switch wires through slot in switch bracket.
(2) Line up switch tab with slot in switch bracket
and push switch into position. Do not pull on the switch
wires to seat switch into bracket, switch damage may
occur. (3) After installation, the switch must be adjusted
and checked for proper operation. Refer to Switch
Adjustment Procedure.
ADJUSTMENT PROCEDURE
When performing switch adjustment, the floor mat
should be removed before beginning adjustment proce-
dures. (1) Set the park brake.
(2) Disconnect clutch cable at the transaxle end of
the cable. (3) Depress clutch pedal, loosen adjusting nut and
slide the striker plate forward to fully compress the
clutch pedal position switch plunger. (4) Tighten adjusting nut to 12 N Im (105 in. lbs.).
(5) Reconnect clutch cable.
The clutch pedal position switch is now ad-
justed. A final check is required to insure that the
switch is ``made'' below the clutch release point. (1) With the park brake set and the vehicle IN
NEUTRAL turn the key to the start position. The
vehicle should not crank. If the vehicle cranks do
not continue with this test. Recheck the switch and
switch adjustment to determine the cause. If the ve-
hicle does not crank proceed to step 2. (2) With the park brake set and the vehicle IN
GEAR turn the key to the start position.
WARNING: BEFORE PERFORMING STEP THREE BE
SURE THAT THE AREA IN FRONT OF THE VEHICLE
IS CLEAR OF OBSTRUCTIONS AND PEOPLE. VE-
HICLE MAY MOVE WHEN PERFORMING THIS TEST.
(3) Slowly depress the clutch pedal and feel for any
vehicle motion when the starter is energized. If there is
no motion the switch is properly adjusted. If motion is
felt, repeat the adjustment procedure.
Fig. 3 Clutch Pedal Position Switch and Components
6 - 4 MANUAL TRANSAXLE CLUTCH Ä

IGNITION OFF DRAW (IOD)
GENERAL INFORMATION
A normal electrical system will draw from 5 to 30
milliamperes from the battery. This is with the ignition
in the OFF position, and all non-ignition controlled cir-
cuits in proper working order. The amount of IOD will
depend on body model and electrical components. A ve-
hicle that has not been operated for an extended period
of approximately 20 days may discharge the battery to
an inadequate level. In this case, the Main Fusible Link
Connector should be disconnected. The Main Fusible
Link connector is located rearward of the battery on the
engine wiring harness (Fig. 19).
If the IOD is over 30 milliamperes, the defect must
be found and corrected before condemning the bat-
tery. Usually, the battery can be charged and re-
turned to service (Fig. 16).
IGNITION OFF DRAW (IOD) TESTS
VEHICLES WITHOUT ELECTRONIC AUTOMATIC TRANSMISSION/LOAD LEVELINGSUSPENSION OR ALARM SYSTEMS
Testing for HIGHER AMPERAGE IOD must be
performed first to prevent damage to most milliamp
meters. A standard 12 volt test light and a milliamp meter
that is equipped with two leads will be used for the
following tests. The milliamp meter should be able to
handle up to two amps.
(1) Verify that all electrical accessories are OFF.
Turn off all lights, close trunk lid, close glove box door,
turn off sun visor vanity lights, close all doors and re- move ignition key. Allow the Illuminated Entry System
if equipped to time out in approximately 30 seconds.
(2) Verify the engine compartment lamp bulb is
working by opening/closing hood. Remove the lamp. (3) Disconnect negative battery cable (Fig. 15).
(4) Connect a typical 12 volt test light between the
negative cable clamp and the negative battery post (Fig.
19). The test light may be brightly lit for up to three
minutes or may not be lit at all. This depending on the
body model or electronic components on the vehicle. (a) The term brightly used throughout the follow-
ing tests. This implies the brightness of the test light
will be the same as if it were connected across the
battery posts. This would be with a fully charged bat-
tery.
(b) The test light or the milliamp meter MUST
be positively connected to the battery post and the
battery cable during all IOD testing. (c) Do not allow the test light or the milliamp
meter to become disconnected during any of the
IOD tests. If this happens, the electronic timer
functions will be started and all IOD tests must be
repeated from the beginning. Clamp the test light
at both ends to prevent accidental disconnection.
(d) After three minutes time has elapsed, the test
light should turn OFF or be dimly lit depending on
the electronic components on the vehicle. If the test
light remains BRIGHTLY lit, do not disconnect test
light. Disconnect each fuse or circuit breaker until
test light is either OFF or DIMLY lit. Refer to the
Front Wheel Drive Car Wiring Diagrams Service
Manual. This will eliminate higher amperage IOD. It
is now safe to install the milliamp meter without
damage to the meter to check for low amperage IOD.
(e) Possible sources of high IOD are usually ve-
hicle lamps trunk lamp, glove compartment, lug-
gage compartment, etc.. (f) If test light is still brightly lit after discon-
necting each fuse and circuit breaker, disconnect
the wiring harness from the generator. Refer to
Generator Testing. Do not disconnect test light.
CAUTION: This last test has higher amperage IOD and
must be performed before going on with low amper-
age IOD tests. The higher amperage IOD must be elim-
inated before hooking up milliamp meter to check for
low amperage IOD. If higher amperage IOD has not
been eliminated, milliamp meter may be damaged.
Most milliamp meters will not handle over one or two
amps. Do not hook up meter if test light is glowing
brightly. Refer to maximum amperage specifications
and instructions supplied with milliamp meter.
After higher amperage IOD has been corrected, low
amperage IOD may be checked. The MAXIMUM IOD=
30 MILLIAMPERES.
Fig. 19 IOD Test
Ä BATTERY/STARTING/CHARGING SYSTEMS DIAGNOSTICS 8A - 9