3: ABS Warning Light Remains Illuminated After Starting Engine

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 ruminates 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 power supply circuit at ABS-ECU connector Am.
Disconnect ABS-ECU connector A-02. If the ABS warning light illuminates, go to Step 2. If it does not illuminate, replace the ABS-ECU.
Then go to Step 3.








STEP 2. Check the harness wires between ABS-ECU connector A-02 and ABS warning light connector C-42.
If any harness wires between ABS-ECU connector A-02 and ABS warning light connector C-42 are damaged, repair them.
Then go to Step 3.

STEP 3. Check symptoms
Confirm the ABS warning light turns off 3 seconds after start-up.