ABS
DTC C1000: Abnormality in stop light switch circuit
CAUTION: If there is any problem in the CAN bus lines, an incorrect diagnostic trouble code may be set. Prior to this diagnosis, diagnose the CAN bus lines.
CIRCUIT OPERATION
ETACS-ECU sends the ON signal generated when the brake pedal is depressed and OFF signal generated when it is released to ABS-ECU via the CAN bus lines.
DTC SET CONDITIONS
This diagnostic trouble code is set in the following case.
^ When the vehicle has run for a long time with the stop light switch turned ON.
^ When there is difference between the stop light switch state and the vehicle's behavior
PROBABLE CAUSES
^ Improper adjustment of stop light switch installation position
^ Malfunction of the stop light switch
^ Malfunction of the stop light
^ Damaged wiring harness and connectors
^ Malfunction of ETACS-ECU
^ Malfunction of the ASC-ECU
DIAGNOSIS
Required Special Tools:
^ MB991958 Scan Tool (M.U.T.-III Sub Assembly)
^ MB991824: Vehicle Communication Interface (V.C.I.)
^ MB991827 M.U.T.-III USB Cable
^ MB991910 M.U.T.-III Main Harness
STEP 1. M.U.T.-III CAN bus diagnostics Using M.U.T.-III, diagnose the CAN bus lines.
Q: Is the check result normal?
YES: Go to Step 3.
NO: Repair the CAN bus lines. After repairing the CAN bus line, go to Step 2.
STEP 2. DTC recheck after repairing the CAN bus line
Q: Is DTC C1000 set?
YES: Go to Step 3.
NO: This diagnosis is complete.
STEP 3. Battery check
Refer to Battery Test.
Q: Is the battery in good condition?
YES: Go to Step 4.
NO: Charge or replace the battery, and the go to Step 16.
STEP 4. Stop light operation check
Check that the stop light is turned "ON" when the brake pedal is depressed, and that the stop light is turned "OFF" when the brake pedal is released.
OK:
When the brake pedal is released: OFF
When the brake pedal is depressed: ON
Q: Is the check result normal?
YES: Go to Step 17.
NO: Go to Step 5.
STEP 5. Check for stop light switch installation
Refer to On-vehicle Service.
Q: Is the check result normal?
YES: Go to Step 6.
NO: Install the stop light switch correctly. Then go to Step 19.
STEP 6. Stop light switch continuity check
1) Remove the stoplight switch.
2) Connect the circuit tester (Q range) to the stop light switch connector terminal Nos. 1 and 2.
3) When continuity does not exist with the plunger pressed from the outer case end face by the dimension shown in the figure, and when continuity exists with the plunger released, the switch is in good condition.
Q: Is the check result normal?
YES: Go to Step 7.
NO: Replace the stop light switch. Then go to Step 19.
STEP 7. Check for diagnostic trouble codes of other systems
Check that no DTC is set by the rear combination light.
Q: Is the check result normal?
YES: Go to Step 8.
NO: Check whether the combination meter-related DTC is set. Then go to Step 19.
STEP 8. ETACS-ECU fuse No.2 check
Q: Is the check result normal?
YES: Go to Step 14.
NO: Go to Step 9.
STEP 9. Connector check: C-129 joint connector, C-124 stoplight switch connector, C-304 ETACS-ECU connector, C-309 ETACS-ECU connector, C-312 ETACS-ECU connector, D-12 intermediate connector, F-01 high-mounted stoplight, D-09 rear combination light (stoplight: RH), D-14 rear combination light (stoplight: LH)
Q: Is the check result normal?
YES: Go to Step 10.
NO: Repair the defective connector. Then, replace fuse No. 2.
STEP 10. Wiring harness check between C-124 stop light switch connector to C-312 ETACS-ECU connector and C-129 joint connector
1) Disconnect C-129 joint connector, C-124 stop light switch connector, and C-312 ETACS-ECU connector.
2) Check the continuity (short to ground) between C-124 stop light switch connector terminal No. 1 and the ground.
OK: No continuity
Q: Is the check result normal?
YES: Go to Step 11.
NO: The short circuit may be present in the wiring harness between C-124 stop light switch connector terminal No. 1 and C-129 joint connector terminal No. 9 or between C-124 stop light switch connector terminal No. 1 and C-312 ETACS-ECU connector terminal No. 16. Repair the damaged wiring harness. Then, replace fuse No. 2.
STEP 11. Harness check between C-124 stop light switch connector and C-304 ETACS-ECU connector
1) Disconnect C-124 stop light switch connector and C-304 ETACS-ECU connector.
2) Check the continuity (short to ground) between C-124 stop light switch connector terminal No. 2 and the ground.
OK: No continuity
Q: Is the check result normal?
YES: Go to Step 12.
NO: The short circuit may be present in the wiring harness between C-124 stop light switch connector terminal No. 2 and C-304 ETACS-ECU connector terminal No. 1. Then, replace fuse No. 2.
STEP 12. Wiring harness check between C-129 joint connector and F-01 high-mounted stop light connector.
1) Disconnect C-129 joint connector and F-01 high-mounted stop light connector.
2) Check the continuity (short to ground) between C-129 joint connector terminal No. 9 and the ground.
OK: No continuity
Q: Is the check result normal?
YES: Go to Step 13.
NO: The short circuit may be present in the wiring harness between C-129 joint connector terminal No. 9 and F-01 high-mounted stop light connector terminal No. 1. Then, replace fuse No. 2.
STEP 13. Wiring harness check between C-129 joint connector and D-14 rear combination light (stop light: LH) connector and between C-129 joint connector and D-09 rear combination light (stop light: RH) connector.
1) Disconnect C-129 joint connector, D-14 rear combination light (stoplight: LH) connector and D-09 rear combination light (stoplight: RH) connector.
2) Check the continuity (short to ground) between C-129 joint connector terminal No. 9 and the ground.
OK: No continuity
Q: Is the check result normal?
YES: Replace fuse No. 2.
NO: The short circuit may be present in the wiring harness between C-129 joint connector terminal No. 9 and D-14 rear combination light (stoplight: LH) connector terminal No.1 or between C-129 joint connector terminal No.9 and D-09 rear combination light (stoplight: RH) connector terminal No. 1. Repair the damaged wiring harness. Then, replace fuse No. 2.
STEP 14. Voltage measurement at C-304 ETACS-ECU connector
CAUTION: The measurement must be performed without the brake pedal depressed (not operated). Measure the voltage between the terminal No. 1 and the body ground by backprobing.
OK: Approximately battery voltage
Q: Is the check result normal?
YES: Go to Step 15.
NO: Replace the ETACS-ECU. Then go to Step 19.
STEP 15. Voltage measurement at C-124 stoplight switch connector
1) Disconnect the connector, and measure at the wiring harness side.
2) Measure the voltage between the terminal No. 2 and the body ground.
OK: Approximately battery voltage
Q: Is the check result normal?
YES: Go to Step 16.
NO: An open circuit may be present in the wiring harness between C-304 ETACS-ECU connector terminal No. 1 and C-124 stop light switch connector terminal No.
2. Repair the wiring harness.
STEP 16. Voltage measurement at C-129 joint connector
CAUTION: The measurement must be performed with the brake pedal depressed.
1) Disconnect the connector, and measure at the wiring harness side.
2) Measure the voltage between the terminal No. 9 and the body ground.
OK: System voltage
Q: Is the check result normal?
YES: Go to Step 17.
NO: An open circuit may be present in the wiring harness between C-129 joint connector terminal No. 9 and C-124 stop light switch connector terminal No. 1. Repair the wiring harness.
STEP 17. Voltage measurement at C-312 ETACS-ECU connector
1) Without disconnecting the connector, measure by backprobing.
2) Measure the voltage between the terminal No. 16 and the body ground.
OK:
The brake pedal is released: Approximately 0 V
The brake pedal is depressed: Approximately battery voltage
Q: Is the check result normal?
YES: Go to Step 18.
NO: An open circuit may be present in the wiring harness between C-312 ETACS-ECU connector terminal No. 16 and C-124 stop light switch connector terminal No. 1. Repair the wiring harness.
STEP 18. Check whether the DTC is reset.
Q: Is DTC 1000 set?
YES: Replace the ABS-ECU, then go to Step 19.
NO: Intermittent malfunction.
STEP 19. Check whether the DTC is reset.
Q: Is DTC 1000 set?
YES: Return to Step 1.
NO: The procedure is complete.