Inspection Procedure 4

INSPECTION PROCEDURE 4: The ABS Warning Light Remains Illuminated after the Engine is Started.









CIRCUIT OPERATION
^ The ABS warning light power is supplied from the ignition switch. The ABS-ECU grounds the circuit to illuminate the light.
^ The ABS-ECU illuminates the ABS warning light for 3 seconds while running self-check. This light is illuminated for 3 seconds upon start-up or when the ignition switch is turned to the ON position with engine stopped.
^ When the ABS-ECU connector is disconnected, the circuit is grounded to illuminate the light.
^ The ABS-ECU controls the continuity to the ABS warning light by turning the power transistor in the unit OFF and ON, respectively.

TECHNICAL DESCRIPTION (COMMENT)
The cause is probably the ABS-ECU malfunction.

TROUBLESHOOTING HINTS
The most likely causes for this case are:
^ Damaged wiring harness or connector
^ Malfunction of the brake modulator hydraulic unit (integrated with ABS-ECU)

DIAGNOSIS
Required Special Tool:
^ MB991223: Harness Set

STEP 1. Check the following connectors.





^ Combination meter connector C-01
^ Intermediate connector C-122





^ ABS-ECU connector B-118
Check the connectors 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 2.
NO: Repair it and then go to Step 4.

STEP 2. Check the following harness wire.








The wire between combination meter connector C-01 (terminal 13) and ABS-ECU connector B-118 (terminal 27)
Q: Is the harness wire damaged?
YES: Repair or replace it and then go to Step 4.
NO: Go to Step 3.

STEP 3. Check the ABS warning light circuit at ABS-ECU connector B-118.





1. Disconnect ABS-ECU connector B-118 and check at the harness side connector.
2. Turn the ignition switch to the ON position.
3. Ground terminal 27 and check the ABS warning light.
Q: Does the ABS warning light go off?
YES: Replace the brake modulator hydraulic unit (integrated with ABS-ECU). Then go to Step 4.
NO: Replace the combination meter. Then go to Step 4.

STEP 4. Retest the system.
Q: Does the ABS warning light turn off in 3 seconds after start-up?
YES: The procedure is complete.
NO: Return to Step 1.