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DTC C1000: Abnormality In Stoplight Switch Circuit: Diagnosis

WARNING: This page is about a different variant/trim than selected.

Required Special Tools: 

  1. 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? 

    1. YES:  Go to Step  3.
    2. NO:  Repair the CAN bus lines. (Refer to CAN BUS DIAGNOSIS TABLE .) On completion, go to Step 2.
  2. STEP 2. DTC recheck after repairing the CAN bus line 

    Q: Is DTC C1000 set? 

    1. YES:  Go to Step 3.
    2. NO:  This diagnosis is complete.
  3. STEP 3. Battery check 

    Refer to BATTERY TEST .

    Q: Is the battery in good condition? 

    1. YES:  Go to Step 4.
    2. NO:  Charge or replace the battery, and the go to Step  15.
  4. 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? 

    1. YES:  Go to Step  15.
    2. NO:  Go to Step 5.
  5. STEP 5. Check for stoplight switch installation 

    Refer to ON-VEHICLE SERVICE .

    Q: Is the check result normal? 

    1. YES:  Go to Step 6.
    2. NO:  Install the stoplight switch correctly. (Refer to ON-VEHICLE SERVICE .) Then, go to Step  20.
  6. STEP 6. Stoplight switch continuity check 
    1. Remove the stoplight switch. (Refer to BRAKE PEDAL .)
    2. Connect the circuit tester (Ω 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 illustration below, and when continuity exists with the plunger released, the switch is in good condition.

    Q: Is the check result normal? 

    1. YES:  Go to Step 7.
    2. NO:  Replace the stoplight switch. (Refer to BRAKE PEDAL .) Then go to Step  20.
    Fig 1: Checking Stoplight Switch Continuity
    G06472432Courtesy of MITSUBISHI MOTOR SALES OF AMERICA.
  7. STEP 7. ETACS-ECU fuse No. 2 check 

    Q: Is the check result normal? 

    1. YES:  Go to Step  11.
    2. NO:  Go to Step 8.
  8. STEP 8. Connector check: 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-16 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? 

    1. YES:  Go to Step 9.
    2. NO:  Repair the defective connector. Then, replace fuse No. 2. Then go to Step  20.
  9. 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.
    3. Measure the resistance between the terminal No. 1 and the body ground.

      OK: No continuity 

    Q: Is the check result normal? 

    1. YES:  Go to Step 10.
    2. NO:  A short circuit may be present in the wiring harness 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  20.
  10. 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? 

    1. YES:  Go to Step 11.
    2. 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  20.
  11. STEP 11. Connector check: C-304 ETACS-ECU connector 

    Q: Is the check result normal? 

    1. YES:  Go to Step 12.
    2. NO:  Repair the damaged connector.
  12. STEP 12. 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? 

    1. YES:  Go to Step 13.
    2. NO:  Replace the ETACS-ECU (Refer to ETACS-ECU ). Then go to Step  20.
  13. STEP 13. Connector check: C-24 Stoplight switch connector 

    Q: Is the check result normal? 

    1. YES:  Go to Step 14.
    2. NO:  Repair the damaged connector.
  14. STEP 14. 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: Approximately system voltage 

    Q: Is the check result normal? 

    1. YES:  Go to Step 15.
    2. 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.
  15. STEP 15. Connector check: C-312 ETACS-ECU connector 

    Q: Is the check result normal? 

    1. YES:  Go to Step 16.
    2. NO:  Repair the damaged connector.
  16. STEP 16. 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: 0 V - 5V (pulse) 

      When the brake pedal is depressed: Approximately system voltage 

    Q: Is the check result normal? 

    1. YES:  Go to Step  19.
    2. NO:  Go to Step 17.
  17. STEP 17. 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? 

    1. YES:  Go to Step 18.
    2. NO:  Replace the wiring harness.
  18. STEP 18. Diagnostic trouble code recheck 

    Q: Is diagnostic trouble code No. C1000 set? 

    1. YES:  Replace the hydraulic unit (ASC-ECU) (Refer to HYDRAULIC UNIT  ). Then go to Step  20.
    2. NO:  Intermittent malfunction (Refer to HOW TO COPE WITH INTERMITTENT MALFUNCTION .)
  19. STEP 19. Check whether the DTC is reset. 

    Erase the DTC.

    Q: Is DTC 1000 set? 

    1. YES:  Replace the hydraulic unit (integrated with ASC-ECU). (Refer to HYDRAULIC UNIT  .) Then go to Step 20.
    2. NO:  Intermittent malfunction. (Refer to HOW TO COPE WITH INTERMITTENT MALFUNCTION .)
  20. STEP 20. Check whether the DTC is reset. 

    Erase the DTC.

    Q: Is DTC 1000 set? 

    1. YES:  Return to Step  1.
    2. NO:  The procedure is complete.
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