DTC 22: Stoplight Switch System: Diagnosis

Required Special Tools: 

• MB991958: Scan Tool (MUT-III Sub Assembly)
  • MB991824: V.C.I.
  • MB991827: MUT-III USB Cable
  • MB991910: MUT-III Main Harness A
• MB991223: Harness Set
• MB992006: Extra Fine Probe
• MB991923: Power Plant ECU Check Harness

1. STEP 1. Using scan tool MB991958, check data list item 74: Brake light switch. 
   CAUTION: To prevent damage to scan tool MB991958, always turn the ignition switch to the "LOCK" (OFF) position before connecting or disconnecting scan tool MB991958.
   1. Connect scan tool MB991958 to the data link connector. (Refer to DIAGNOSTIC TROUBLESHOOTING STRATEGY ).
   2. Turn the ignition switch to the "ON" position.
   3. Set scan tool MB991958 to data reading mode for auto-cruise control system. (Refer to DIAGNOSTIC TROUBLESHOOTING STRATEGY ).
      • Item 74, Brake light switch.
        • When the brake pedal is depressed, the display on scan tool MB991958 should be "ON".
        • When the brake pedal is released, the display on scan tool MB991958 should be "OFF".
   4. Turn the ignition switch to the "LOCK" (OFF) position.
   5. Disconnect scan tool MB991958.
      Fig 1: Connecting Scan Tool To Data Link Connector

      Courtesy of MITSUBISHI MOTOR SALES OF AMERICA.

   Q: Is the switch operating properly? 

   YES :  Go to  Step 14.

   NO :  Go to Step 2.

2. STEP 2. Check the stoplight operation. 

   Check the stoplight operation.

   • When the brake pedal is depressed, the stoplight will illuminate.
   • When the brake pedal is released, the stoplight does not illuminate.

   Q: Does the stoplight illuminate when the brake pedal is depressed and go out when the brake pedal is released? 

   YES :  Go to Step 3.

   NO :  Go to  Step 6.

3. STEP 3. Measure the terminal voltage at ECM < M/T > or PCM < A/T > connector B-18. 
   1. Disconnect all the connectors from the ECM < M/T > or PCM < A/T >.
      Fig 2: Identifying ECM Or PCM Connector B-18

      Courtesy of MITSUBISHI MOTOR SALES OF AMERICA.
   2. Connect special tool MB991923 between the ECM < M/T > or PCM < A/T > and the body-side harness connector.
   3. Turn the ignition switch to the "ON" position.
      Fig 3: Connecting Special Tool MB991923 Between ECM Or PCM & Body-Side Harness Connector

      Courtesy of MITSUBISHI MOTOR SALES OF AMERICA.
   4. Measure the terminal voltage between special tool 18-pin connector terminal 9 (ECM < M/T > or PCM < A/T > connector B-18 terminal 9) and ground.
      • When the brake pedal is depressed, the voltage should measure battery positive voltage (approximately 12 volts).
      • When the brake pedal is released, the voltage should measure 1 volt or less.
        Fig 4: Measuring Terminal Voltage Between Special Tool 18-Pin Connector Terminal No. 9 & Ground

        Courtesy of MITSUBISHI MOTOR SALES OF AMERICA.
   5. Turn the ignition switch to the "LOCK" (OFF) position.
   6. Disconnect special tool MB991923 between the ECM < M/T > or PCM < A/T > and the body-side harness connector.
   7. Reconnect all the connectors to the ECM < M/T > or PCM < A/T >.

   Q: Is the measured voltage battery positive voltage (approximately 12 volts) when the brake pedal is depressed and 1 volt or less when the brake pedal is released? 

   YES :  Go to  Step 13.

   NO :  Go to Step 4.

4. STEP 4. Check ECM < M/T > or PCM < A/T > connector B-18 and joint connector (1) C-28 for loose, corroded or damaged terminals, or terminals pushed back in the connector. 

   Q: Are the connectors and terminals in good condition? 

   YES :  Go to Step 5.

   NO :  Repair or replace the damaged components. (Refer to HARNESS CONNECTOR INSPECTION ). Then go to  Step 22.

   Fig 5: Checking ECM Or PCM Connector B-18

   Courtesy of MITSUBISHI MOTOR SALES OF AMERICA.
   Fig 6: Identifying Connector C-28

   Courtesy of MITSUBISHI MOTOR SALES OF AMERICA.
5. STEP 5. Check the harness wire between ECM < M/T > or PCM < A/T > connector B-18 terminal 9 and joint connector (1) C-28 terminal 14 for damage. 

   Q: Is the harness wire in good condition? 

   YES :  Go to  Step 13.

   NO :  Repair the damaged harness wire. Then go to  Step 22.

   Fig 7: Checking Harness Wire Between ECM Or PCM Connector B-18

   Courtesy of MITSUBISHI MOTOR SALES OF AMERICA.
   Fig 8: Identifying Connector C-28

   Courtesy of MITSUBISHI MOTOR SALES OF AMERICA.
6. STEP 6. Measure the power supply voltage at stoplight switch connector C-103 by backprobing. 
   1. Disconnect stoplight switch connector C-103.
      Fig 9: Identifying Stoplight Switch Connector C-103

      Courtesy of MITSUBISHI MOTOR SALES OF AMERICA.
   2. Measure the power supply voltage between stoplight switch connector C-103 terminal 2 and ground.
   3. Reconnect stoplight switch connector C-103.

   Q: Is the measured voltage battery positive voltage (approximately 12 volts)? 

   YES :  Go to  Step 10.

   NO :  Go to Step 7.

   Fig 10: Measuring Power Supply Voltage Between Stoplight Switch Connector C-103 Terminal No. 2 & Ground

   Courtesy of MITSUBISHI MOTOR SALES OF AMERICA.
7. STEP 7. Check stoplight switch connector C-103 for loose, corroded or damaged terminals, or terminals pushed back in the connector. 
   Fig 11: Checking Stoplight Switch Connector C-103

   Courtesy of MITSUBISHI MOTOR SALES OF AMERICA.

   Q: Are the connector and terminals in good condition? 

   YES :  Go to Step 8.

   NO :  Repair or replace the damaged components. (Refer to HARNESS CONNECTOR INSPECTION ). Then go to  Step 22.

8. STEP 8. Check the harness wire between stoplight switch connector C-103 terminal 2 and fuse number 11 at the relay box at engine compartment for damage. 

   Q: Is the harness wire in good condition? 

   YES :  Go to Step 9.

   NO :  Repair the damaged harness wire. Then go to  Step 22.

   Fig 12: Checking Harness Wire Between Stoplight Switch Connector C-103

   Courtesy of MITSUBISHI MOTOR SALES OF AMERICA.
   Fig 13: Locating Fuse Number 11 At Relay Box

   Courtesy of MITSUBISHI MOTOR SALES OF AMERICA.
9. STEP 9. Check the fuse number 11 at the relay box at engine compartment. 

   Q: Is the fuse in good condition? 

   YES :  Go to Step 10.

   NO :  Check the stoplight system harness and replace the fuse. Then go to  Step 22.

   Fig 14: Checking Fuse No. 11 At Relay Box At Engine Compartment

   Courtesy of MITSUBISHI MOTOR SALES OF AMERICA.
10. STEP 10. Check the stoplight switch. 
    1. Remove the stoplight switch. (Refer to BRAKE PEDAL ).
    2. Connect an ohmmeter to the stoplight switch between terminals 1 and 2.
    3. Check for continuity between the terminals when the plunger of the stoplight switch is pushed in and when it is released.
    4. The stoplight switch is operating properly if the circuit is open between terminals 1 and 2 when the plunger is pushed in to a depth of within 4.0 mm (0.16 inch) from the outer case edge surface, and if the resistance value is less than 2 ohms between terminals 1 and 2 when it is released.
       Fig 15: Connecting Ohmmeter To Stoplight Switch Between Terminals No. 1 & 2

       Courtesy of MITSUBISHI MOTOR SALES OF AMERICA.

    Q: Is the stoplight switch operating properly? 

    Fig 16: Checking Stoplight Switch Operation

    Courtesy of MITSUBISHI MOTOR SALES OF AMERICA.

    YES :  Install the stoplight switch. (Refer to BRAKE PEDAL ). Then go to Step 11.

    NO :  Replace the stoplight switch. (Refer to BRAKE PEDAL ). Then go to  Step 22.

11. STEP 11. Check stoplight switch connector C-103 and joint connector (1) C-28 for loose, corroded or damaged terminals, or terminals pushed back in the connector. 

    Q: Are the connectors and terminals in good condition? 

    YES :  Go to Step 12.

    NO :  Repair or replace the damaged components. (Refer to HARNESS CONNECTOR INSPECTION ). Then go to  Step 22.

    Fig 17: Identifying Connectors C-28 & C-103

    Courtesy of MITSUBISHI MOTOR SALES OF AMERICA.
12. STEP 12. Check the harness wire between stoplight switch connector C-103 terminal 1 and joint connector (1) C-28 terminal 12 for damage. 

    Q: Is the harness wire in good condition? 

    YES :  Go to Step 13.

    NO :  Repair the damaged harness wire. Then go to  Step 22.

    Fig 18: Checking Harness Wire Between Connectors C-28 & C-103

    Courtesy of MITSUBISHI MOTOR SALES OF AMERICA.
13. STEP 13. Using scan tool MB991958, check data list item 74: Brake light switch. 
    CAUTION: To prevent damage to scan tool MB991958, always turn the ignition switch to the "LOCK" (OFF) position before connecting or disconnecting scan tool MB991958.
    1. Connect scan tool MB991958 to the data link connector. (Refer to DIAGNOSTIC TROUBLESHOOTING STRATEGY ).
       Fig 19: Connecting Scan Tool To Data Link Connector

       Courtesy of MITSUBISHI MOTOR SALES OF AMERICA.
    2. Turn the ignition switch to the "ON" position.
    3. Set scan tool MB991958 to data reading mode for auto-cruise control system. (Refer to DIAGNOSTIC TROUBLESHOOTING STRATEGY ).
       • Item 74, Brake light switch.
         • When the brake pedal is depressed, the display on scan tool MB991958 should be "ON".
         • When the brake pedal is released, the display on scan tool MB991958 should be "OFF".
    4. Turn the ignition switch to the "LOCK" (OFF) position.
    5. Disconnect scan tool MB991958.

    Q: Is the switch operating properly? 

    YES :  Go to  Step 21.

    NO :  Replace the ECM < M/T > or PCM < A/T >. (Refer to ENCRYPTED CODE REGISTRATION CRITERIA TABLE ). Then go to  Step 22.

14. STEP 14. Using scan tool MB991958, check data list item 89: Normally closed brake switch. 
    CAUTION: To prevent damage to scan tool MB991958, always turn the ignition switch to the "LOCK" (OFF) position before connecting or disconnecting scan tool MB991958.
    1. Connect scan tool MB991958 to the data link connector. (Refer to DIAGNOSTIC TROUBLESHOOTING STRATEGY ).
       Fig 20: Connecting Scan Tool To Data Link Connector

       Courtesy of MITSUBISHI MOTOR SALES OF AMERICA.
    2. Turn the ignition switch to the "ON" position.
    3. Set scan tool MB991958 to data reading mode for auto-cruise control system. (Refer to DIAGNOSTIC TROUBLESHOOTING STRATEGY ).
       • Item 89, Normally closed brake switch.
         • When the brake pedal is depressed, the display on scan tool MB991958 should be "ON".
         • When the brake pedal is released, the display on scan tool MB991958 should be "OFF".
    4. Turn the ignition switch to the "LOCK" (OFF) position.
    5. Disconnect scan tool MB991958.

    Q: Is the switch operating properly? 

    YES :  Go to  Step 21.

    NO :  Go to Step 15.

15. STEP 15. Measure the terminal voltage at ECM < M/T > or PCM < A/T > connector B-19. 
    1. Disconnect all the connectors from the ECM < M/T > or PCM < A/T >.
       Fig 21: Measuring Terminal Voltage ECM Or PCM Connector B-19

       Courtesy of MITSUBISHI MOTOR SALES OF AMERICA.
    2. Connect special tool MB991923 between the ECM < M/T > or PCM < A/T > and the body-side harness connector.
    3. Turn the ignition switch to the "ON" position.
       Fig 22: Connecting Special Tool MB991923 Between ECM Or PCM & Body-Side Harness Connector

       Courtesy of MITSUBISHI MOTOR SALES OF AMERICA.
    4. Measuring terminal voltage between special tool 23-pin connector (without red tape) terminal 33 (ECM < M/T > or PCM < A/T > connector B-19 terminal 33) and ground.
       • When the brake pedal is depressed, the voltage should measure battery positive voltage (approximately 12 volts).
       • When the brake pedal is released, the voltage should measure 1 volt or less.
         Fig 23: Measuring Terminal Voltage Between Special Tool 23-Pin Connector & Ground

         Courtesy of MITSUBISHI MOTOR SALES OF AMERICA.
    5. Turn the ignition switch to the "LOCK" (OFF) position.
    6. Disconnect special tool MB991923 between the ECM < M/T > or PCM and the body-side harness connector.
    7. Reconnect all the connectors to the ECM < M/T > or PCM.

    Q: Is the measured voltage battery positive voltage (approximately 12 volts) when the brake pedal is depressed and 1 volt or less when the brake pedal is released? 

    YES :  Go to  Step 20.

    NO :  Go to Step 16.

16. STEP 16. Check the stoplight switch. 
    1. Remove the stoplight switch. (Refer to BRAKE PEDAL ).
    2. Connect an ohmmeter to the stoplight switch between terminals 3 and 4.
       Fig 24: Connecting Ohmmeter To Stoplight Switch Between Terminals No. 3 & 4

       Courtesy of MITSUBISHI MOTOR SALES OF AMERICA.
    3. Check for continuity between the terminals when the plunger of the stoplight switch is pushed in and when it is released.
       Fig 25: Check For Continuity As Plunger Of Switch Is Operated

       Courtesy of MITSUBISHI MOTOR SALES OF AMERICA.
    4. The stoplight switch is operating properly if the circuit is open between terminals 3 and 4 when the plunger is released, and if resistance value is less than 2 ohms between terminals 3 and 4 when the plunger is pushed in to a depth of within 4.5 mm (0.18 inch) from the outer case edge surface.

    Q: Is the stoplight switch operating properly? 

    YES :  Install the stoplight switch. (Refer to BRAKE PEDAL ). Then go to Step 17.

    NO :  Replace the stoplight switch. (Refer to BRAKE PEDAL ). Then go to  Step 22.

17. STEP 17. Check ECM < M/T > or PCM < A/T > connector B-19 and stoplight switch connector C-103 for loose, corroded or damaged terminals, or terminals pushed back in the connector. 

    Q: Are the connectors and terminals in good condition? 

    YES :  Go to Step 18.

    NO :  Repair or replace the damaged components. (Refer to HARNESS CONNECTOR INSPECTION ). Then go to  Step 22.

    Fig 26: Identifying ECM Or PCM Connector B-19

    Courtesy of MITSUBISHI MOTOR SALES OF AMERICA.
    Fig 27: Identifying Connector C-103

    Courtesy of MITSUBISHI MOTOR SALES OF AMERICA.
18. STEP 18. Check the harness wire between ECM < M/T > or PCM < A/T > connector B-19 terminal 33 and stoplight switch connector C-103 terminal 3 for damage. 

    Q: Is the harness wire in good condition? 

    YES :  Go to Step 19.

    NO :  Repair the damaged harness wire. Then go to  Step 22.

    Fig 28: Identifying ECM Or PCM Connector B-19

    Courtesy of MITSUBISHI MOTOR SALES OF AMERICA.
    Fig 29: Identifying Connector C-103

    Courtesy of MITSUBISHI MOTOR SALES OF AMERICA.
19. STEP 19. Check the harness wire between stoplight switch connector C-103 terminal 4 and ground for damage. 

    Q: Is the harness wire in good condition? 

    YES :  Go to Step 20.

    NO :  Repair the damaged harness wire. Then go to  Step 22.

    Fig 30: Identifying Stoplight Switch Connector C-103

    Courtesy of MITSUBISHI MOTOR SALES OF AMERICA.
    Fig 31: Locating Ground Terminal

    Courtesy of MITSUBISHI MOTOR SALES OF AMERICA.
20. STEP 20. Using scan tool MB991958, check data list item 89: Normally closed brake switch. 
    CAUTION: To prevent damage to scan tool MB991958, always turn the ignition switch to the "LOCK" (OFF) position before connecting or disconnecting scan tool MB991958.
    1. Connect scan tool MB991958 to the data link connector. (Refer to DIAGNOSTIC TROUBLESHOOTING STRATEGY ).
       Fig 32: Connecting Scan Tool To Data Link Connector

       Courtesy of MITSUBISHI MOTOR SALES OF AMERICA.
    2. Turn the ignition switch to the "ON" position.
    3. Set scan tool MB991958 to data reading mode for auto-cruise control system. (Refer to DIAGNOSTIC TROUBLESHOOTING STRATEGY ).
       • Item 89, Normally closed brake switch.
         • When the brake pedal is depressed, the display on scan tool MB991958 should be "ON".
         • When the brake pedal is released, the display on scan tool MB991958 should be "OFF".
    4. Turn the ignition switch to the "LOCK" (OFF) position.
    5. Disconnect scan tool MB991958.

    Q: Is the switch operating properly? 

    YES :  Go to Step 21.

    NO :  Replace the ECM < M/T > or PCM < A/T >. (Refer to ENCRYPTED CODE REGISTRATION CRITERIA TABLE ). Then go to  Step 22.

21. STEP 21. Read the diagnostic trouble codes. 

    Read the diagnostic trouble codes. (Refer to DIAGNOSTIC TROUBLESHOOTING STRATEGY ).

    Q: Is DTC P22 set? 

    YES :  Replace the ECM < M/T > or PCM < A/T >. (Refer to ENCRYPTED CODE REGISTRATION CRITERIA TABLE ). Then go to Step 22.

    NO :  It can be assumed that this malfunction is intermittent. (Refer to HOW TO COPE WITH INTERMITTENT MALFUNCTION ).

22. STEP 22. Read the diagnostic trouble codes. 

    Read the diagnostic trouble codes. (Refer to DIAGNOSTIC TROUBLESHOOTING STRATEGY ).

    Q: Is DTC P22 set? 

    YES :  Return to  Step 1.

    NO :  The procedure is complete.