• Low system voltage. If low system voltage is de-
tected by the (CAB), the (CAB) will turn on the Amber
Anti-Lock Warning Lamp until normal system voltage
is achieved. Once normal voltage is seen at the (CAB),
normal operation resumes.
• 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 Warning
Lamp will also be turned on.
• Low Accumulator Pressure. Low Accumulator Pres-
sure 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 opera-
tion.
Additionally, any condition that results in interrup-
tion 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 SYSTEM DIAGNOSTIC FEATURES
SYSTEM SELF DIAGNOSIS
The ABS system is equipped with a diagnostic capa-
bility 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 until
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. 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 II Diagnostic Tester.
START-UP CYCLE
The START-UP CYCLE takes place immediately
after the ignition switch is turned on. It is an electrical
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
approximately 1 - 2 seconds to complete.
DRIVE-OFF CYCLE
The DRIVE-OFF CYCLE takes place when the ve-
hicle reaches about 3 miles per hour the first time after
an ignition reset. During this test, the modulator
solenoid valves are activated briefly to test their func-
tion. The DRIVE-OFF CYCLE will be bypassed if you
drive-off with the service brake pedal depressed.
LATCHING VERSUS NON-LATCHING FAULTS
Some faults detected by the (CAB) are latching. The
fault is latched and (ABS) function is disabled until the
ignition switch is reset (turned OFF/ON). Thus (ABS)
function is disabled even if the original fault has
disappeared during the ignition cycle in which it oc-
curred. Other faults are non-latching; any warning
lights that are turned on are only on as long as the
fault condition exists. As soon as the condition goes
away. The Amber Anti-Lock Warning Light is turned
off. Although a fault code will be set in most cases.
(Example: low accumulator fault will not be stored for
a time of 2 minutes after the fault is detected).
BENDIX ABS SYSTEMS DIAGNOSTICS
The Bendix Anti-Lock 10 Brake System diagnostics.
Beyond the basic mechanical diagnostics, systems and
components covered earlier in this section, is accom-
plished by using the DRB II diagnostic tester. See
testing procedures outlined in the Bendix Anti-Lock 10
Diagnostics Manual for the 1992 M.Y.
Please reference the above mentioned manual. For
any further diagnostic service procedures that are
required on the Bendix Anti-Lock 10 Brake System,
requiring the use of the DRB II diagnostic tester.
ON CAR HYDRAULIC ABS COMPONENT SERVICE
WARNING: FAILURE TO FULLY DE-PRESSURIZE THE
HYDRAULIC ACCUMULATOR BEFORE PERFORM-
ING HYDRAULIC SYSTEM SERVICE OPERATIONS.
COULD RESULT IN INJURY TO SERVICE PERSON-
NEL AND OR DAMAGE TO PAINTED SURFACES. SEE
SECTION 2 FOR ADDITIONAL WARNINGS AND CAU-
TIONS.
GENERAL SERVICE PRECAUTIONS
The following are general precautions that should be
observed when servicing the Anti-Lock Brake System
and/or other vehicle systems. Failure to observe these
precautions may result in Anti-Lock brake system
damage.
If welding work is to be performed on the vehicle,
using an electric arc welder, the (CAB) connector
should be disconnected during the welding operation.
.
ANTI-LOCK BRAKES
5 - 75