TCS or ASC
DTC C1000: Abnormality in stoplight 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.
^ Whenever the ECU is replaced, ensure that the CAN bus lines are normal.
^ When the hydraulic unit (integrated with ASC-ECU) is replaced, always perform the calibration of steering wheel sensor, G and yaw rate sensor, brake fluid pressure sensor, cut valve, and inlet valve.
CIRCUIT OPERATION
ETACS-ECU sends the ON signal generated when the brake pedal is depressed and OFF signal generated when the pedal is released to ASC-ECU via CAN bus lines.
DTC SET CONDITIONS
This diagnostic trouble code is set in the following case.
^ The vehicle has run for a long time with the stoplight switch turned ON.
^ The OFF status of the stoplight switch does not match the vehicle behavior.
PROBABLE CAUSES
^ Improper adjustment of stoplight switch installation position
^ Malfunction of the stoplight switch
^ Malfunction of the stoplight
^ 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 A
STEP 1. Using scan tool MB991958, diagnose the CAN bus lines.
Using scan tool MB991958, diagnose the CAN bus lines.
Q: Is the check result normal?
YES: Go to Step 3.
NO: Repair the CAN bus lines. (Refer to CAN Bus Diagnosis table Can Bus Diagnostics Table.) On completion, 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 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. Stoplight operation check
Check the stoplight operation when the brake pedal is depressed. Check that all the stoplight illuminates when the brake pedal is depressed and that it goes out when the brake pedal is released.
OK:
When the brake pedal is released: OFF
When the brake pedal is depressed: Illuminates
Q: Is the check result normal?
YES: Go to Step 18.
NO: Go to Step 5.
STEP 5. Check for stoplight switch installation
Refer to On-vehicle Service Brake Pedal Check and Adjustment.
Q: Is the check result normal?
YES: Go to Step 6.
NO: Install the stoplight switch correctly. Then, go to Step 23.
STEP 6. Stoplight switch continuity check
1) Remove the stoplight switch.
2) Connect the circuit tester (ohms range) to the stoplight 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 stoplight switch. Then go to Step 23.
STEP 7. ETACS-ECU fuse No.2 check
Q: Is the check result normal?
YES: Go to Step 12.
NO: Go to Step 8.
STEP 8. Connector check: C-43 joint connector, C-47 intermediate connector, C-48 stoplight switch connector, C-304 ETACS-ECU connector, C-309 ETACS-ECU connector, C-312 ETACS-ECU connector, D-11 intermediate connector, D-17 intermediate connector, F-05 high-mounted stoplight, F-06 rear combination light (stoplight: RH), F-25 rear combination light (stoplight: LH), F-27 intermediate connector
Q: Is the check result normal?
YES: Go to Step 9.
NO: Repair the defective connector. Then, replace fuse No. 2. Then go to Step 23.
STEP 9. Resistance measurement at C-48 stoplight switch connector
1) Disconnect C-48 stoplight switch connector, and measure at the wiring harness side.
2) Disconnect C-312 ETACS-ECU connector and C-43 joint connector.
3) Measure the resistance between the terminal No.1 and the body ground.
OK: No continuity
Q: Is the check result normal?
YES: Go to Step 10.
NO: A short circuit may be present in the wiring harness between C-43 joint connector terminal No.2 and C-48 stoplight switch connector terminal No.1 or between C-312 ETACS-ECU connector terminal No.16 and C-48 stoplight switch connector terminal No.1. Repair the wiring harness if necessary, and then replace fuse No.2. Then go to Step 23.
STEP 10. Resistance measurement at C-48 stoplight switch connector
1) Disconnect C-48 stoplight switch connector, and measure at the wiring harness side.
2) Disconnect C-304 ETACS-ECU connector.
3) Measure the resistance between the terminal No.2 and the body ground.
OK: No continuity
Q: Is the check result normal?
YES: Go to Step 11.
NO: A short circuit may be present in the wiring harness between C-304 ETACS-ECU connector terminal No.1 and C-48 stoplight switch connector terminal No.2. Repair the wiring harness if necessary, and then replace fuse No.2. Then go to Step 23.
STEP 11. Resistance measurement at C-43 joint connector
1) Disconnect C-43 joint connector, and measure at the wiring harness side.
2) Disconnect F-06 rear combination light (stoplight: RH) connector, F-25 rear combination light (stoplight: LH) connector, F-05 high-mounted stoplight connector.
3) Measure the resistance between the terminal No.2 and the body ground.
OK: No continuity
Q: Is the check result normal?
YES: Replace fuse No.2. Then go to Step 23.
NO: A short circuit may be present in the wiring harness between C-43 joint connector terminal No.2 and F-06 rear combination light (stoplight: RH) connector terminal No.4 or between C-43 joint connector terminal No.2 and F-25 rear combination light (stoplight: LH) connector terminal No.4 or between C-43 joint connector terminal No.2 and F-05 high-mounted stoplight connector terminal No.1. Repair the wiring harness if necessary, and then replace fuse No.2. Then go to Step 23.
STEP 12. Connector check: C-304 ETACS-ECU connector
Q: Is the check result normal?
YES: Go to Step 13.
NO: Repair the damaged connector.
STEP 13. Measure the voltage at the C-304 ETACS-ECU connector.
CAUTION:
Measure while the brake pedal is not depressed. Measure the voltage between terminal No. 1 and the body ground by backprobing.
OK: Battery positive voltage
Q: Is the check result normal?
YES: Go to Step 14.
NO: Replace the ETACS-ECU. Then go to Step 23.
STEP 14. Connector check: C-24 Stoplight switch connector
Q: Is the check result normal?
YES: Go to Step 15.
NO: Repair the damaged connector.
STEP 15. Measure the voltage at C-48 stoplight switch connector.
1) Disconnect C-48 stoplight switch connector, and measure the voltage at harness connector side.
2) Measure the voltage between the terminal No.2 and the body ground.
OK: Battery positive 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-48 stoplight switch connector terminal No. 2. Repair the wiring harness.
STEP 16. Connector check: C-43 joint connector
Q: Is the check result normal?
YES: Go to Step 17.
NO: Repair the damaged connector.
STEP 17. Voltage measurement at C-43 joint connector
CAUTION:
Measure while the brake pedal is depressed.
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: Battery positive 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-43 joint connector terminal No.2 and C-48 stoplight switch connector terminal No.1. Repair the wiring harness.
STEP 18. Connector check: C-312 ETACS-ECU connector
Q: Is the check result normal?
YES: Go to Step 19.
NO: Repair the damaged connector.
STEP 19. Measure the voltage at the C-312 ETACS-ECU connector.
1) Measure by backprobing without disconnecting the connector.
2) Measure the voltage between the terminal No.16 and the body ground.
OK:
When the brake pedal is released: 0V -5V (pulse)
When the brake pedal is depressed: Approximately battery positive voltage
Q: Is the check result normal?
YES: Go to Step 22.
NO: Go to Step 20.
STEP 20. Check the wiring harness between C-312 ETACS-ECU connector terminal No.16 and C-48 stoplight switch connector terminal No.1
^ Check the signal line for open circuit.
Q: Is the check result normal?
YES: Go to Step 21.
NO: Replace the wiring harness.
STEP 21. Diagnostic trouble code recheck
Q: Is diagnostic trouble code No.C1000 set?
YES: Replace the hydraulic unit (ASC-ECU). Then go to Step 23.
NO: Intermittent malfunction.
STEP 22. Check whether the DTC is reset.
Q: Is DTC 1000 set?
YES: Replace the hydraulic unit (incorporates in ASC-ECU). Then go to Step 23.
NO: Intermittent malfunction.
STEP 23. Check whether the DTC is reset.
Q: Is DTC 1000 set?
YES: Return to Step 1.
NO: The procedure is complete.