3: TCL Warning Light Does Not Illuminate When Key Is Turned on
CIRCUIT OPERATION
- Power to the TCL warning light is supplied from the ignition switch. The ABS-ECU grounds the circuit to illuminate the light.
The ABS-ECU illuminates the TCL warning light for 3 seconds while running self-check. This light can be illuminated for 3 seconds upon start-up or ignition switch ON, engine stopped.
TECHNICAL DESCRIPTION (COMMENT)
The cause may be: an open circuit in the TCL warning light power supply circuit, a blown TCL warning light bulb or ABS-ECU.
TROUBLESHOOTING HINTS
The most likely causes for this condition:
- Blown fuse
- Damaged wiring harness or connector
- Burnt out TCL warning light bulb
- Malfunction of the ABS-ECU
DIAGNOSIS
Required Special Tool: MB991223: Harness Set
STEP 1. Check the power supply circuit at ABS-ECU connector A-02.
1. Disconnect connector A-02 and measure at the harness side.
2. Turn the ignition switch to "ON" position.
3. The TCL warning light should illuminate when terminal on
If it does not illuminate, go to Step 2.
If it illuminates, replace the hydraulic unit (integrated with ABS-ECU). Then go to Step 9.
STEP 2. Check the TCL indicator light bulb.
1. Remove the combination meter.
2. Check the TCL indicator light bulb.
If the TCL indicator light bulb is burned out, replace it. Then go to Step 9.
If the TCL indicator light bulb is not burned out, go to Step 3.
STEP 3. Check the combination meter for the continuity.
1. Remove the combination meter.
2. Remove the TCL warning light bulb. Then measure the resistance between the bulb terminals.
3. Install the TCL warning light bulb to the combination meter, and then measure the resistance between connector C-41 terminals 52 and 42. The resistance reading at this time should be much the same as the resistance measured at step (2).
If the two resistance values are extremely different each other, replace the combination meter (printed circuit board).
If the two resistance values are much the same, go to Step 4.
STEP 4. Check the power supply circuit at the combination meter.
1. Disconnect connector C-41, and check at the harness side.
2. Turn the ignition switch to "ON" position.
3. Measure the voltage between terminal 52 and ground. It should be approximately 12 V (battery positive voltage).
If not approximately 12 V, go to Step 7.
If approximately 12 V, go to Step 5.
STEP 5. Check connectors C-41, C-94, and Amp. Check connectors C-41, C-94, and A-02. (Refer to Harness Connector Inspection.) Initial Inspection and Diagnostic Overview
If defective, repair the connector. Then go to Step 9.
If not defective, go to Step 6.
STEP 6. Check the continuity between the combination meter and the ABS-ECU. Check the harness wire between combination meter C-41 and ABS-ECU connector A-02 for continuity.
If open circuit, repair the wire. Then go to Step 9.
If less than 2 ohm, go to Step 9.
STEP 7. Check connectors C-41, C-104, and A-101. Check connectors C-41, C-104, and C-101. (Refer to Harness Connector Inspection.) Initial Inspection and Diagnostic Overview
If defective, repair the connector. Then go to Step 9.
If not defective, go to Step 8.
STEP 8. Check the continuity between the ignition switch (IG1) and the combination meter.
Check the harness wire between the ignition switch (IG1) and terminal 52 of combination meter connector C-41 for continuity.
If open circuit, repair the wire. Then go to Step 9.
If less than 2 ohm, go to Step 9.
STEP 9. Check symptoms Confirm the TCL warning light illuminates for 3 seconds when the ignition switch is turned to "ON" position with engine stopped or upon start-up.