Inspection Procedure 2

INSPECTION PROCEDURE 2: When the Ignition Switch is Turned to the "ON" Position (Engine Stopped or After Start-up), the ABS Warning Light does not Illuminate.

Part 1 Of 2:

Part 2 Of 2:

CIRCUIT OPERATION
^ The ABS warning light power is supplied from the ignition switch. The ABS-ECU grounds the circuit to illuminate the light by operating the ABS relay.
^ The ABS-ECU controls the continuity to the ABS warning light by turning the power transistor in the unit "ON" and "OFF" to turn the ABS relay "OFF" and "ON".

TECHNICAL DESCRIPTION (COMMENT)
The cause may be: an open circuit in the ABS warning light circuit, a blown light bulb, or a short circuit to ground between the ABS relay and the ABS-ECU.

TROUBLESHOOTING HINTS (The most likely causes for this case:)
^ Blown fuse
^ Damaged wiring harness or connector
^ Burnt out ABS warning light bulb
^ Malfunction of the ABS relay
^ Malfunction of the hydraulic unit (integrated with ABS-ECU)

DIAGNOSIS

Required Special Tool:
^ MB991223: Harness Set

STEP 1. Check the ABS warning light circuit at ABS-ECU connector A-85.








1. Disconnect ABS-ECU connector A-85.
2. Turn the ignition switch to the "ON" position.
Q: Does the ABS warning light illuminate?
YES: Replace the hydraulic unit (integrated with ABS-ECU) and then go to Step 15.
NO: Go to Step 2.

STEP 2. Check the ABS relay.





1. Remove the ABS relay.





2. Check for continuity between terminals 3 - 4 when battery voltage is applied between terminals 1 - 2.
Q: Is the ABS relay in good condition?
YES: Go to Step 3.
NO: Replace the ABS relay. Then go to Step 15.

STEP 3. Check the ABS warning light circuit at ABS relay connector A-35.





1. Disconnect ABS relay connector A-35.
2. Ground terminal 3 of the ABS relay harness side connector.
3. Turn the ignition switch to the "ON" position, and then ABS warning light should illuminate.
Q: Does the ABS warning light illuminate?
YES: Go to Step 11.
NO: Go to Step 4.

STEP 4. Check the ABS warning light bulb.
1. Remove the combination meter.
2. Check the ABS warning light bulb.
Q: Is the bulb burned out?
YES: Replace the bulb and then go to Step 15.
NO: Go to Step 5.

STEP 5. Measure the combination meter for continuity.





1. Remove the combination meter.
2. Remove the ABS warning light bulb. Then measure the resistance between the bulb terminals.
3. Install the ABS warning light bulb to the combination meter, and then measure the resistance between connector C-04 terminal 24 and connector C-05 terminal 10. The resistance reading at this time should be much the same as the resistance measured at step (2).
Q: Are the two resistance values extremely different each other?
YES: Replace the combination meter (printed circuit board) and then go to Step 15.
NO: Go to Step 6.

STEP 6. Measure the combination meter power supply circuit.





1. Disconnect connector C-04, and check at the harness side.
2. Turn the ignition switch to the "ON" position.
3. Measure the voltage between terminal 24 and ground. It should measure approximately 12 volts (battery positive voltage.)
Q: Is battery positive voltage (approximately 12 volts) present?
YES: Go to Step 9.
NO: Go to Step 7.

STEP 7. Check connectors C-04, D-06 and D-08 for loose, corroded or damaged terminals, or terminals pushed back in the connector.











Check connectors C-04, D-06 and D-08.
Q: Are the connectors and terminals in good condition?
YES: Go to Step 8.
NO: Repair it and then go to Step 15.

STEP 8. Check for continuity between the ignition switch (IG1) and the combination meter connector C-04 (terminal No. 24).





Q: Is there any continuity (less than 2 ohms) between the ignition switch (IG1) and combination meter connector C-04 (terminal No. 24)?
YES: Go to Step 15.
NO: Repair the harness wire and then go to Step 15.

STEP 9. Check harness connectors A-35, C-05 and C-17 for loose, corroded or damaged terminals, or terminals pushed back in the connector.











Q: Are the connectors and terminals in good condition?
YES: Go to Step 10.
NO: Repair it and then go to Step 15.

STEP 10. Check the harness wire between ABS relay connector A-35 (terminal No. 3) and combination meter connector C-05 (terminal No.10).








Q: Is the harness wire between ABS relay connector A-35 (terminal No. 3) and combination meter connector C-05 (terminal No.10) damaged?
YES: Repair it and then go to Step 15.
NO: Go to Step 15.

STEP 11. Check ABS relay connector A-35 for loose, corroded or damaged terminals, or terminals pushed back in the connector.





Q: Are the connector and terminals in good condition?
YES: Go to Step 12.
NO: Repair or replace it. Then go to Step 15.





STEP 12. Check the harness wire between ABS relay connector A-35 (terminal No.4) and ground.





NOTE: After inspecting joint connector C-14, inspect the wire. If joint connector C-14 is damaged, repair or replace it. If the connector has been repaired or replaced, go to Step 15.

Q: Is the harness wire between ABS relay connector A-35 (terminal No.4) and ground damaged?
YES: Repair it and then go to Step 15.
NO: Go to Step 13.

STEP 13. Check ABS-ECU connector A-85 for loose, corroded or damaged terminals, or terminals pushed back in the connector.





Q: Are the connector and terminals in good condition?
YES: Go to Step 14.
NO: Repair or replace it. Then go to Step 15.

STEP 14. Check the harness wire between ABS relay connector A-35 (terminal No.1) and ABS-ECU connector A-85 (terminal No.16).





Q: Is the harness wire between ABS relay connector A-35 (terminal No.1) and ABS-ECU connector A-85 (terminal No.16) damaged?
YES: Repair it and then go to Step 15.
NO: Go to Step 15.

STEP 15. Retest the system.
Q: Does the ABS warning light illuminate for 3 seconds when the ignition switch is turned to the "ON" position with engine stopped or upon start-up?
YES: The procedure is complete.
NO: Return to Step 1.