3: ABS Warning Light Remains Illuminated

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





Part 1 of 2





Part 2 of 2

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 continuity to the ABS warning light by turning the power transistor in the unit "ON" and "OFF" to turn the ABS warning relay "ON" and "OFF."

TECHNICAL DESCRIPTION (COMMENT)
The cause is probably an ABS warning light relay or hydraulic unit (integrated with ABS-ECU) malfunction.

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

DIAGNOSIS

Required Special Tool:
^ MB991223: Harness Set








STEP 1. Check the ABS warning light relay continuity.
1. Remove the ABS warning light relay.
2. Check the continuity between terminal number 1 and number 3 and between terminal number 5 and number 2 at the ABS warning light relay.
Q: Is the ABS warning light relay normal?
YES: Go to Step 2.
NO: Replace the ABS warning light and then go to Step 6.





STEP 2. Check the power supply circuit at the ABS warning light relay connector A-13X.
1. Start the engine.
2. Measure at the relay box in engine compartment side the voltage between the terminal 3 and ground.
Q: Is the voltage approximately 12 volts?
YES: Go to Step 4.
NO: Go to Step 3.











STEP 3. Check the harness wire between ignition switch (IG2) and ABS warning light relay connector A-13X.

NOTE: After inspecting intermediate connectors C-17, C-84 and C-87 inspect the wires. If intermediate connector C-17, C-84 or C-87 is damaged, repair or replace it. If the connector has been repaired or replaced, go to Step 6.

Q: Are any harness wire between the ignition switch (IG1) and ABS warning light relay connector A-13X damaged?
YES: Repair the harness wire and then go to Step 6.
NO: Go to Step 4.














STEP 4. Check the harness wire between ABS-ECU connector A-03 and ABS warning light relay connector A-13X.

NOTE: After inspecting intermediate connectors C-12 and C-17, inspect the wire. If intermediate connector C-12 or C-17 is damaged, repair or replace if. If the connector has been repaired or replaced, go to Step 6.

Q: Is the harness wire between the ABS-ECU connector A-03 and ABS warning light relay connector A-13X damaged?
YES: Repair the harness wire and then go to Step 6.
NO: Go to Step 6.








STEP 5. Check the harness wire between combination meter connector C-30 and ABS warning light relay connector A-13X.
1. Remove the combination meter.
2. Check the harness wire between combination meter connector C-30 terminal 8 and ABS warning light relay connector A-13X terminal 5.
Q: Is the harness wire between the combination meter connector C-30 and ABS warning light relay connector A-13X damaged?
YES: Repair the harness wire and then go to Step 6.
NO: Replace the ABS-ECU then go to Step 6.

STEP 6. Check symptom.
Q: Does the ABS warning light remain illuminated after the engine is started?
YES: Return to Step 1.
NO: This diagnosis is complete.