K 2500 Truck 4WD V8-379 6.2L DSL VIN C FI (1989)
ABS Light: Customer Interest
Brakes - Code 9 Misdiagnosis, RWAL
GMC NUMBER:
89-T-38
GROUP:
5 - Brakes
DATE:
March, 1989
CORPORATE
NUMBER:
965004
SUBJECT:
REAR WHEEL ANTI-LOCK (RWAL) CODE 9 MISDIAGNOSIS
MODELS:
1988-89 C/K, 1989 S/T AND M VANS
The instrument panel (I.P.) brake warning light will only come on when an abnormal condition exists within the RWAL system. The ECU module will
only store one condition (or code) at a time. The vehicle should be test driven after the initial condition has been resolved to determine if any other
conditions (codes) exist. It should be noted that if the I.P. Brake warning light is not on, it can be induced to come on by
grounding diagnostic terminal "H" to "A" for more than 20 seconds. When this occurs, a Code 9 will be set. This is a peculiarity with the RWAL system,
and should not be interpreted as a faulty condition. Technicians who have accidentally induced a Code 9 in this manner should simply dear the code prior
to returning the vehicle to the customer.
