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 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 can be 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 by the ABS warning light relay ON operation.
^ The ABS-ECU controls the continuity to the ABS warning light by turning the power transistor in the unit OFF and ON to turn the ABS warning light relay ON and OFF, respectively.

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

TROUBLESHOOTING HINTS (The most likely causes for this condition:)
^ Damaged wiring harness or connector
^ 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 wiring harness between the ABS warning light relay and the ABS warning light.





1. Disconnect ABS warning light relay connector C-213.
2. Turn the ignition switch to the ON position.
Q: Does the ABS warning light illuminate?
YES: Go to Step 2.
NO: Go to Step 3.

STEP 2. Check the harness wire between the combination meter connector C-01 terminal 13 and the ABS warning light relay connector C-213 terminal 5.








NOTE: After inspecting combination meter connector C-01 and ABS warning light relay connector C-213, inspect the wire. If combination meter connector C-01 or ABS warning light relay connector C-213 is damaged, repair or replace it. If the connector has been repaired or replaced, go to Step 8.

Q: Is the harness wire between combination meter connector C-01 and ABS warning light relay connector C-213 damaged?
YES: Repair the harness wire and then go to Step 8.
NO: Replace the combination meter (printed circuit board) and then go to Step 8.

STEP 3. Check the ABS warning light relay.








1. Remove the ABS warning light relay.
2. Check for continuity between terminals 2 - 5.
Q: Is the ABS warning light relay continuity?
YES: Go to Step 4.
NO: Replace it and then go to Step 8.

STEP 4. Check the ABS warning light relay power supply circuit.





1. Disconnect ABS warning light relay connector C-213 and measure at the junction block side.
2. Turn the ignition switch to the ON position.
3. Measure the voltage between terminal 1 and ground. It should be approximately 12 volts (battery positive voltage).
Q: Is battery positive voltage (approximately 12 volts) present?
YES: Go to Step 6.
NO: Go to Step 5.

STEP 5. Check the harness wire between connector C-214 terminal 26 and the ABS warning light relay connector C-213 terminal 1.





NOTE: After inspecting connector C-214 and ABS warning light relay connector C-213, inspect the wire. If connector C-214 or ABS warning light relay connector C-213 is damaged, repair or replace it. If the connector has been repaired or replaced, go to Step 8.

Q: Is the harness wire between connector C-214 terminal 26 and the ABS warning light relay connector C-213 terminal 1 damaged?
YES: Repair the harness wire and then go to Step 8.
NO: Go to Step 8.

STEP 6. Check the ABS warning light circuit at ABS-ECU connector B-118.





1. Disconnect ABS-ECU connector B-118 and measure at the harness side.
2. Connect ABS-ECU connector B-118 terminal 12 to ground.
3. Turn the ignition switch to the ON position.
Q: Does the ABS warning light go off?
YES: Replace the hydraulic unit (integrated with ABS-ECU) and then go to Step 8.
NO: Go to Step 7.

STEP 7. Check the harness wire between ABS-ECU connector B-118 terminal 12 and ABS warning light relay connector C-213 terminal 3.








NOTE: After inspecting connector C-122, inspect the wire. If connector C-122 is damaged, repair or replace it. If the connector has been repaired or replaced, go to Step 8.





Q: Is the harness wire between ABS-ECU connector B-118 terminal 12 and ABS warning light relay connector C-213 terminal 3 damaged?
YES: Repair it and then go to Step 8.
NO: Go to Step 8.

STEP 8. 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.