DTC 22: Stoplight Switch System: Diagnosis

Required Special Tools: 

• MB991958: Scan Tool (M.U.T.-III Sub Assembly)
  • MB991824: V.C.I.
  • MB991827: M.U.T.-III USB Cable
  • MB991910: M.U.T.-III Main Harness A
• MB991223: Harness Set
• MB992006: Extra Fine Probe

1. STEP 1. Using scan tool MB991958, diagnose the CAN bus line. 
   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 AUTO-CRUISE CONTROL SYSTEM DIAGNOSIS  ).
   2. Turn the ignition switch to the "ON" position.
   3. Diagnose the CAN bus line (Refer to AUTO-CRUISE CONTROL SYSTEM DIAGNOSIS  ).
   4. Turn the ignition switch to the "LOCK" (OFF) position.
   5. Disconnect scan tool MB991958.

   Q: Is the check result satisfactory? 

   YES:  Go to Step 2.

   NO:  Repair the CAN bus lines (Refer to CAN BUS DIAGNOSTICS CHART ). Then go to  Step 15.

   Fig 1: Connecting Special Tool To Data Link Connector

   Courtesy of MITSUBISHI MOTOR SALES OF AMERICA.
2. STEP 2. Using scan tool MB991958, check the data list item 74: Brake light switch. 
   1. Connect scan tool MB991958 to the data link connector (Refer to AUTO-CRUISE CONTROL SYSTEM DIAGNOSIS  ).
   2. Turn the ignition switch to the "ON" position.
   3. Set scan tool MB991958 to data reading mode for cruise control system (Refer to AUTO-CRUISE CONTROL SYSTEM DIAGNOSIS  ).
      • 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 9.

   NO:  Go to Step 3.

3. STEP 3. Using scan tool MB991958, check the ETACS system data list item 290: Brake light switch. 
   1. Connect scan tool MB991958 to the data link connector (Refer to AUTO-CRUISE CONTROL SYSTEM DIAGNOSIS  ).
   2. Turn the ignition switch to the "ON" position.
   3. Set scan tool MB991958 to data reading mode for ETACS system (Refer to DATA LIST REFERENCE TABLE  ).
      • Item 290, 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:  Replace the ECM. Refer to REMOVAL AND INSTALLATION for 2.4L engines or REMOVAL AND INSTALLATION for 3.0L engines. After replacing ECM, go to  Step 15.

   NO:  Go to Step 4.

4. STEP 4. Check stoplight switch connector C-124 and ETACS-ECU connector C-304 and C-312 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 15.

5. STEP 5. Check the harness wire between ETACS-ECU connector C-304 terminal 1 and stoplight switch connector C-124 terminal 2, and check the harness wire stoplight switch connector C-124 terminal 1 and ETACS-ECU connector C-312 terminal 16 for damage. 

   Q: Are the harness wires in good condition? 

   YES:  Go to Step 6.

   NO:  Repair the damaged harness wire. Then go to  Step 15.

6. STEP 6. 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 2: Checking Continuity Between Terminals When Plunger Of Stoplight Switch Pushed

      Courtesy of MITSUBISHI MOTOR SALES OF AMERICA.

   Q: Is the stoplight switch operating properly? 

   YES:  Install the stoplight switch (Refer to BRAKE PEDAL ). Then go to Step 7.

   NO:  Replace the stoplight switch (Refer to BRAKE PEDAL ). Then go to  Step 15.

   Fig 3: Checking Stoplight Switch Operating

   Courtesy of MITSUBISHI MOTOR SALES OF AMERICA.
7. STEP 7. Check fuse number 2 at the ETACS-ECU. 

   Q: Is the fuse in good condition? 

   YES:  Go to Step 8.

   NO:  Check the stoplight system harness and replace the fuse. Then go to  Step 15.

   Fig 4: Locating Fuse Number 2 At ETACS-ECU

   Courtesy of MITSUBISHI MOTOR SALES OF AMERICA.
8. STEP 8. Using scan tool MB991958, check the ETACS system data list item 290: Brake light switch. 
   1. Connect scan tool MB991958 to the data link connector (Refer to AUTO-CRUISE CONTROL SYSTEM DIAGNOSIS  ).
   2. Turn the ignition switch to the "ON" position.
   3. Set scan tool MB991958 to data reading mode for ETACS system (Refer to DATA LIST REFERENCE TABLE  ).
      • Item 290, 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 15

   NO:  Replace the ETACS-ECU (Refer to REMOVAL AND INSTALLATION ). Then go to  Step 15.

9. STEP 9. Using scan tool MB991958, check the data list item 89: Normally closed brake switch. 
   1. Connect scan tool MB991958 to the data link connector (Refer to AUTO-CRUISE CONTROL SYSTEM DIAGNOSIS  ).
   2. Turn the ignition switch to the "ON" position.
   3. Set scan tool MB991958 to data reading mode for cruise control system (Refer to AUTO-CRUISE CONTROL SYSTEM DIAGNOSIS  ).
      • 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 14.

   NO:  Go to Step 10.

10. STEP 10. Check ECM connector B-11 and stoplight switch connector C-124 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 11.

    NO:  Repair or replace the damaged components (Refer to HARNESS CONNECTOR INSPECTION ). Then go to  Step 15.

11. STEP 11. Check the harness wire between ECM connector B-11 terminal 108 and stoplight switch connector C-124 terminal 3, and check the harness wire between stoplight switch connector C-124 terminal 4 and ground for damage. 

    Q: Are the harness wires in good condition? 

    YES:  Go to Step 12.

    NO:  Repair the damaged harness wire. Then go to  Step 15.

    Fig 5: Identifying ETACS-ECJ And Ground Terminal

    Courtesy of MITSUBISHI MOTOR SALES OF AMERICA.
12. STEP 12. 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.
    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 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.
       Fig 6: Checking Stoplight Switch Continuity

       Courtesy of MITSUBISHI MOTOR SALES OF AMERICA.

    Q: Is the stoplight switch operating properly? 

    YES:  Install the stoplight switch (Refer to BRAKE PEDAL ). Then go to Step 13.

    NO:  Replace the stoplight switch (Refer to BRAKE PEDAL ). Then go to  Step 15.

    Fig 7: Checking Stoplight Switch Operation

    Courtesy of MITSUBISHI MOTOR SALES OF AMERICA.
13. STEP 13. Using scan tool MB991958, check the data list item 89: Normally closed brake switch. 
    1. Connect scan tool MB991958 to the data link connector (Refer to AUTO-CRUISE CONTROL SYSTEM DIAGNOSIS  ).
    2. Turn the ignition switch to the "ON" position.
    3. Set scan tool MB991958 to data reading mode for cruise control system (Refer to AUTO-CRUISE CONTROL SYSTEM DIAGNOSIS  ).
       • 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:  It can be assumed that this malfunction is intermittent (Refer to HOW TO COPE WITH INTERMITTENT MALFUNCTIONS ).

    NO:  Replace the ECM. Refer to REMOVAL AND INSTALLATION for 2.4L engines or REMOVAL AND INSTALLATION for 3.0L engines. After replacing ECM, go to  Step 15.

14. STEP 14. Read the diagnostic trouble codes. 
    1. Erase diagnostic trouble code (Refer to AUTO-CRUISE CONTROL SYSTEM DIAGNOSIS  ).
    2. Turn the ignition switch to the "ON" position, and press the "ON/OFF" switch to turn the cruise control system to ON (turn on the "CRUISE" indicator light).
    3. With the cruise control switches not operated, depress the brake pedal for several seconds, and then read the diagnostic trouble codes (Refer to AUTO-CRUISE CONTROL SYSTEM DIAGNOSIS  ).

    Q: Is DTC P22 set? 

    YES:  Replace the ECM. Refer to REMOVAL AND INSTALLATION for 2.4L engines or REMOVAL AND INSTALLATION for 3.0L engines. After replacing ECM, go to Step 15.

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

15. STEP 15. Using scan tool MB991958, check the data list item 74: Brake light switch, item 89: Normally closed brake switch. 
    1. Connect scan tool MB991958 to the data link connector (Refer to AUTO-CRUISE CONTROL SYSTEM DIAGNOSIS  ).
    2. Turn the ignition switch to the "ON" position.
    3. Set scan tool MB991958 to data reading mode for cruise control system (Refer to AUTO-CRUISE CONTROL SYSTEM DIAGNOSIS  ).
       • 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".
       • 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 16.

    NO:  Return to  Step 2.

16. STEP 16. Read the diagnostic trouble codes. 
    1. Erase diagnostic trouble code (Refer to AUTO-CRUISE CONTROL SYSTEM DIAGNOSIS  ).
    2. Turn the ignition switch to the "ON" position, and press the "ON/OFF" switch to turn the cruise control system to ON (turn on the "CRUISE" indicator light).
    3. With the cruise control switches not operated, depress the brake pedal for several seconds, and then read the diagnostic trouble codes (Refer to AUTO-CRUISE CONTROL SYSTEM DIAGNOSIS  ).

    Q: Is DTC P22 set? 

    YES:  Return to  Step 1.

    NO:  The procedure is complete.