Inspection Procedure 3

INSPECTION PROCEDURE 3: The ABS Warning Light Remains Illuminated After the Engine is Started.

NOTE: This diagnosis procedure is limited to cases where communication with the scan tool is possible (ABS-ECU power supply is normal) and no diagnostic trouble code outputs.

CIRCUIT OPERATION
^ The ABS-ECU controls the illumination of the ABS warning light by turning the power transistor in the control unit ON and OFF
^ The ABS-ECU illuminates the ABS warning light on start-up. It turns the light off after 3 seconds when the ABS-ECU completes the self-check.

TECHNICAL DESCRIPTION (COMMENT)
The cause is probably the ABS-ECU and hydraulic unit assembly malfunction.:

TROUBLESHOOTING HINTS (The most likely causes for this condition:)
^ Damaged wiring harness
^ Malfunction of the hydraulic unit (integrated with ABS-ECU)

DIAGNOSIS

Required Special Tool:
^ MB991223: Harness Set

STEP 1. Check the harness wires between ABS-ECU connector A-02 terminal 21 and combination meter connector C-101 terminal 21.











NOTE: After inspecting intermediate connector C-212 inspect the wire. If intermediate connector C-212 is damaged, repair or replace it. If the connector has been repaired or replaced, go to Step 3.

Q: Is any harness wire between ABS-ECU connector A-02 terminal 21 and combination meter connector C-101 terminal 21 damaged?
YES: Repair it and then go to Step 3.
NO: Go to Step 2.

STEP 2. Check the harness wires between ABS-ECU connector A-02 terminal 19 and ground.








Q: Is the harness wire between ABS-ECU connector A-02 terminal 19 and ground damaged?
YES: Repair it and then go to Step 3.
NO: Replace the ABS-ECU and then go to Step 3.

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