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/EBTCM serial data line terminal. Switched ignition voltage is supplied through EBCM/EBTCM switched ignition terminal, battery voltage through EBCM/EBTCM battery feed terminal and switched battery voltage through EBCM/EBTCM switched battery input terminal. Ground is through EBCM/EBTCM terminal "E".

1. Indicates if EBCM/EBTCM is transmitting data.
2. Checks for serial data line malfunction.
3. Checks for proper connection of Tech 1 scan tester to DLC.
4. Checks fuse for open.
5. Checks fuse for open.
6. Checks for high resistance in EBCM/EBTCM 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/EBTCM.
12. Ensures short to ground is not due to physical damage of circuit.
13. Checks for possible short to ground in switched ignition circuit.
14. Isolates short to ground to either circuitry or EBCM/EBTCM.
15. Ensures short to ground is not due to physical damage of circuitry.
16. Checks for proper battery voltage at EBCM/EBTCM.
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 EBTCM.