Diagnostic System Check: Notes

Diagnostic system check is an organized approach to identifying a problem created by an Anti-Lock Brake System (ABS) malfunction. This should be the starting point for any ABS diagnosis because it directs technician to next logical step in diagnosing a complaint.

Serial data is transmitted through EBCM terminal No. 2. Switched ignition voltage is supplied through EBCM terminal No. 14, battery voltage through EBCM terminal No. 15 and switched battery voltage through EBCM terminal "A". Ground is through EBCM terminal "B".

1. Indicates if EBCM is transmitting data.
2. Checks for serial data line malfunction.
3. Checks for proper connection of Tech 1 scan tester to DLC.
4. Checks multifunction alarm module fuse for open.
5. Checks fuse No. 4 for open.
6. Checks for high resistance in EBCM ground circuit.
7. Checks for current codes.
8. Checks for proper ABS warning light operation.
9. Checks for history codes.
10. Checks for possible short to ground in battery voltage feed circuit.
11. Checks for possible short to ground in EBCM.
12. Checks for short to ground in battery voltage circuit between multifunction alarm module and EBCM.
13. Ensures short to ground is not due to physical damage of circuit.
14. Checks for possible short to ground in switched ignition circuit.
15. Isolates short to ground to either circuitry or EBCM.
16. Checks for proper battery voltage at EBCM.
17. Checks for high resistance in battery voltage feed circuit.
18. Checks for high resistance in switched ignition circuit.
19. Ensures malfunction is not due to poor terminal contact.
20. Checks for high resistance in switched ignition circuit between fuse block and EBCM.