2: TCL Indicator Light Does Not Illuminate

INSPECTION PROCEDURE 2: When the Ignition Switch is Turned to the "ON" (Engine Stopped or After Start-up), the TCL Indicator Light does not illuminate.





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
^ Power to the TCL indicator light is supplied from the ignition switch. The ABS-ECU grounds the circuit to turn the light ON.
^ The ABS-ECU illuminates the TCL indicator light for 3 seconds while running self-check. This light can be illuminated for 3 seconds upon start-up or key ON, engine stopped.

TECHNICAL DESCRIPTION (COMMENT)
The cause may be: an open circuit in the TCL indicator light power supply circuit, a blown TCL indicator light bulb or ABS-ECU.

TROUBLESHOOTING HINTS
^ Blown fuse
^ Damaged wiring harness or connector
^ Burnt out TCL indicator 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-03.
1. Disconnect connector A-03 and measure at the harness side.
2. Turn the ignition switch to the ~ON" position.
3. The TCL indicator light should illuminate if terminal 13 is grounded.
Q: Does the TCL indicator light illuminate?
YES: Replace the hydraulic unit (integrated with ABS-ECU) and then go to Step 9.
NO: Go to Step 2.

STEP 2. Check the TCL indicator light bulb.
1. Remove the combination meter.
2. Check the TCL indicator light bulb.
Q: Is the TCL indicator light bulb burned out?
YES: Replace the bulb and then go to Step 9.
NO: Go to Step 3.





STEP 3. Check the combination meter for the continuity.
1. Remove the combination meter.
2. Remove the TCL indicator light bulb. Then measure the resistance between the bulb terminals.
3. Install the TCL indicator light bulb to the combination meter, and then measure the resistance between connector C-29 terminals 29 and 33. 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).
NO: (much the same): Go to Step 4.





STEP 4. Check the power supply circuit at the combination meter.
1. Disconnect connector C-29, and check at the harness side.
2. Turn the ignition switch to the "ON" position.
3. Measure the voltage between terminal 29 and ground. It should be approximately 12 volts (battery positive voltage).
Q: Is the voltage approximately 12 volts?
YES: Go to Step 5.
NO: Go to Step 7.











STEP 5. Check connectors C-12, C-29, and A-03.
Check connectors C-12, C-29, and A-03.
Q: Is any of connectors damaged?
YES: Repair it and then go to Step 9.
NO: Go to Step 6.








STEP 6. Check the continuity between the combination meter and the ABS-ECU.
Check the continuity between combination meter connector C-29 (terminal 33) and ABS-ECU connector A-03 (terminal 13).
Q: Is there the continuity between combination meter connector C-29 and ABS-ECU connector A-03?
YES: Go to Step 9.
NO: Repair the harness wire and then go to Step 9.








STEP 7. Check connectors C-29, C-84, and C-87.
Check connectors C-29, C-84, and C-87.
Q: Are any of the connectors damaged?
YES: Repair it and then go to Step 9.
NO: Go to Step 8.





STEP 8. Check the continuity between the ignition switch (IG1) and the combination meter.
Q: Is there any continuity (less than 2 ohms) between the ignition switch (IG1) and combination meter connector C-29 (terminal 29)?
YES: Go to Step 9.
NO: Repair the harness wire and then go to Step 9.

STEP 9. Check symptom.
Q: Does the TCL indicator light illuminate 3 seconds when the ignition switch is turned to the "ON" position with engine stopped or upon start-up?
YES: This diagnosis is complete.
NO: Return to Step 1.