Inspection Procedure 3

INSPECTION PROCEDURE 3: When the Ignition Key is Turned to the ON position (Engine Stopped), the ABS Warning Light does not Illuminate.









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 may be an open circuit in the ABS warning light power supply circuit, a blown ABS warning light bulb, or a short circuit to ground between the ABS warning light and the ABS-ECU.

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

DIAGNOSIS
Required Special Tool:
^ MB991223: Harness Set

STEP 1. Check the ABS warning light circuit at ABS-ECU connector B-118.





1. Disconnect ABS-ECU connector B-118.
2. Turn the ignition switch to the ON position.
Q: Does the ABS warning light illuminate?
YES: Replace the brake modulator hydraulic unit (integrated with ABS-ECU). Then go to Step 10.
NO: Go to Step 2.

STEP 2. Check the power supply circuit. Measure the voltage at combination meter connector C-01.





1. Disconnect combination meter connector C-01 and measure at the harness side.
2. Start the engine.
3. Measure the voltage between terminal 9 and ground. It should measure battery voltage (approximately 12 volts).
Q: Is battery positive voltage (approximately 12 volts) present?
YES: Go to Step 5.
NO: Go to Step 3.

STEP 3. Check the following connectors.





^ Combination meter connector C-01





^ Junction block connectors C-211, C-214
^ Joint connector C-23 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 4.
NO: Repair it and then go to Step 10.

STEP 4. Check the following harness wire.








The wire between junction block connector C-211 (terminal 6) and combination meter connector C-01 (terminal 9)
Q: Is the harness wire damaged?
YES: Repair or replace it and then go to Step 10.
NO: Go to Step 10.

STEP 5. Check the ground circuit at combination meter connector C-02.





1. Disconnect combination meter connector C-02 and measure at the harness side.
2. Measure the resistance between terminal 48 and ground. It should measure less than 2 ohms.
Q: Is the resistance 2 ohms or less?
YES: Go to Step 8.
NO: Go to Step 6.

STEP 6. Check the following connector.





Combination meter connector C-02
Check the connector for loose, corroded or damaged terminals, or terminals pushed back in the connector.
Q: Are the connector and terminals in good condition?
YES: Go to Step 7.
NO: Repair it and then go to Step 10.

STEP 7. Check the following harness wire.








The wire between combination meter connector C-02 (terminal 48) and ground (No.7)
Q: Is the harness wire damaged?
YES: Repair or replace it and then go to Step 10.
NO: Go to Step 10.

STEP 8. 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 9.
NO: Repair it and then go to Step 10.

STEP 9. 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 10.
NO: Replace the combination meter. Then go to Step 10.

STEP 10. Retest the system.
Q: Does the ABS warning light illuminate for 3 seconds when the ignition switch is turned to the ON position with engine stopped or upon start-up?
YES: The procedure is complete.
NO: Return to Step 1.