Inspection Procedure 2

INSPECTION PROCEDURE 2: The ABS Warning Light does not Illuminate, when the Ignition Key is Turned to "ON." (Engine Stopped or After Start-up)

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 ignition switch to the "ON" position, engine stopped.

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 malfunction of the ABS-ECU.

TROUBLESHOOTING HINTS
The most likely causes for this case:
^ Blown fuse
^ Damaged wiring harness or connector
^ Burnt out ABS warning light bulb
^ Malfunction of the ABS-ECU

DIAGNOSIS

Required Special Tool:
^ MB991223: Harness Set

STEP 1. Check the ABS warning light circuit at ABS-ECU connector A-02.

1) Disconnect ABS-ECU connector A-02.
2) Turn the ignition switch to the "ON" position.

Q: Does the ABS warning light illuminate?
YES: Replace the hydraulic unit (integrated with ABS-ECU) and then go to Step 7.
NO: Go to Step 2.

STEP 2. Check the ABS warning light bulb.
1) Remove the combination meter.
2) Check the ABS warning light bulb.

Q: Is the bulb burned out?
YES: Replace the bulb and then go to Step 7.
NO: Go to Step 3.

STEP 3. Check the combination meter for continuity.
1) Remove the combination meter.
2) Remove the ABS warning light bulb. Then measure the resistance between the bulb terminals.





3) Install the ABS warning light bulb to the combination meter, and then measure the resistance between connector C-101 terminal 12 and terminal 21. The resistance reading at this time should be much the same as the resistance measured at step (2).

Q: Are the two resistance values extremely different each other?
YES: Replace the combination meter (printed circuit board) and then go to Step 7.
NO: Go to Step 4.
STEP 4. Check the combination meter power supply circuit.





1) Disconnect connector C-101, and check at the harness side.
2) Turn the ignition switch to the "ON" position.
3) Measure the voltage between terminal 12 and ground. It should be battery positive voltage (approximately 12 volts).

Q: Is battery positive voltage (approximately 12 volts) present?
YES: Go to Step 5.
NO: Go to Step 6.

STEP 5. Check the harness wire between the combination meter connector C-101 terminal 21 and the ABS-ECU A-02 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 7.

Q: Is any harness wire between combination meter connector C-101 terminal 21 and ABS-ECU connector A 02 terminal 21 damaged?
YES: Repair it and then go to Step 7.
NO: Go to Step 7.

STEP 6. Check the harness wire between ignition switch (IG1) connector C-202 terminal 2 and combination meter connector C-101 terminal 12.











NOTE: After inspecting intermediate connectors C-308 and C311, inspect the wires. If intermediate connector C-308 or C311 is damaged, repair or replace it. If the connector has been repaired or replaced, go to Step 7.

Q: Is any harness wire between the ignition switch (IG1) connector C-202 terminal 2 and the combination meter connector C-101 terminal 12 damaged?
YES: Repair it and then go to Step 7.
NO: Go to Step 7.

STEP 7. Check symptom.
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.