C 1500 Truck 2WD V6-262 4.3L (1989)
ABS Light: All Technical Service Bulletins
Brakes - Clarification On ABS Trouble Codes
GMC NUMBER:
89-T45
GROUP:
5 - Brakes
DATE:
April, 1989
CORPORATE
NUMBER:
965006
SUBJECT:
CLARIFICATION ON REAR WHEEL ANTI-LOCK (RWAL) TROUBLE CODES
MODELS:
1988-89C/K AND 1989 S/T AND M-VANS
Some confusion may exist about how to read the trouble codes for the RWAL system on the models listed above. After grounding diagnostic terminal
""A", the brake light will begin its flashing sequence.
IMPORTANT:
The brake light must be on before grounding "A". If the brake light is not on, and terminal "H" is ground "A", you will induce a false
Code 9 in the system.
The following is an example of how to read a Code 4:
Begin the count with the long flash. Continue counting the next three short flashes. The next flash will be a long flash which starts the sequence over
again.
IMPORTANT:
Sometimes the first count sequence will be incomplete. However, subsequent counts will be accurate.
EXAMPLE:
CODE 4
FIRST LONG
SHORT
SHORT
SHORT
LONG
SHORT
FLASH
FLASH
FLASH
FLASH
FLASH
FLASH
1
2
3
4
1
2
START
END
START