DTC 22

DTC 22: Stoplight Switch System

Stoplight Switch System Circuit (Part 1):

Stoplight Switch System Circuit (Part 2):

CIRCUIT OPERATION
- As for the brake light switch, when the brake pedal is depressed, the signal is transmitted from the ETACS-ECU to the ECM via CAN bus line.
- As for the normally closed brake switch, when the brake pedal is depressed, battery positive voltage is supplied to the stoplight switch (terminal 3), and when the brake pedal is not depressed, the voltage of ECM terminal 108 will indicate 0 volt.

DTC SET CONDITIONS

Check Condition
- The "CRUISE" indicator light illuminates.

Judgement Criteria
- Open/short in stop light switch circuit.
- Open circuit in the brake switch circuit (between ECM terminal 108 and ground).
- Malfunction of CAN bus line.

TROUBLESHOOTING HINTS (The most likely causes for this case:)
- Malfunction of CAN bus system.
- Damaged harness or connector.
- Malfunction of the stoplight switch.
- Malfunction of the ETACS-ECU
- Malfunction of the ECM

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

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. Scan Tool Connecting
2. Turn the ignition switch to the "ON" position.
3. Diagnose the CAN bus line.
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 Controller Area Network, Diagnosis - Can Bus Diagnostic Chart). Then go to Step 15.

STEP 2. Using scan tool MB991958, check data list item 74: Brake light switch.

1. Connect scan tool MB991958 to the data link connector. Scan Tool Connecting
2. Turn the ignition switch to the "ON" position.
3. Set scan tool MB991958 to data reading mode for auto-cruise control system. Reading Diagnostic Trouble Codes
- 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.

STEP 3. Using scan tool MB991958, check ETACS system data list item 290: Brake light switch.

1. Connect scan tool MB991958 to the data link connector. Scan Tool Connecting
2. Turn the ignition switch to the "ON" position.
3. Set scan tool MB991958 to data reading mode for ETACS system (Refer to Chassis Electrical, ETACS -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. When the ECM is replaced, register the encrypted code (Refer to Troubleshooting - ID Code Registration Judgment Table). Then go to Step 15.

NO : Go to Step 4.

STEP 4. Check fuse number 2 at the ETACS-ECU.






Q: Is the fuse in good condition?

YES : Go to Step 5.

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

STEP 5. Check the stoplight switch.

1. Remove the stoplight switch (Refer to Basic Brake System, 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.






Q: Is the stoplight switch operating properly?

YES : Install the stoplight switch (Refer to Basic Brake System, Brake Pedal). Then go to Step 6.

NO : Replace the stoplight switch (Refer to Basic Brake System, Brake Pedal). Then go to Step 15.

STEP 6. Check stoplight switch connector C-32 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 7.

NO : Repair or replace the damaged components (Refer to General (Electrical), Harness Connector Inspection). Then go to Step 15.

STEP 7. Check the harness wire between ETACS-ECU connector C-304 terminal 1 and ETACS-ECU connector C-312 terminal 16 for damage.

Q: Is the harness wire in good condition?

YES : Go to Step 8.

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

STEP 8. Using scan tool MB991958, check ETACS system data list item 290: Brake light switch.

1. Connect scan tool MB991958 to the data link connector. Scan Tool Connecting
2. Turn the ignition switch to the "ON" position.
3. Set scan tool MB991958 to data reading mode for ETACS system (Refer to Chassis Electrical, ETACS - 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 9.

NO : Replace the ETACS-ECU (Refer to Chassis Electrical, ETACS-ECU). Then go to Step 15.

STEP 9. Using scan tool MB991958, check data list item 89: Normally closed brake switch.

1. Connect scan tool MB991958 to the data link connector. Scan Tool Connecting
2. Turn the ignition switch to the "ON" position.
3. Set scan tool MB991958 to data reading mode for auto-cruise control system. Reading Diagnostic Trouble Codes
- 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.

STEP 10. Check the stoplight switch.

1. Remove the stoplight switch (Refer to Basic Brake System, 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.






Q: Is the stoplight switch operating properly?

YES : Install the stoplight switch (Refer to Basic Brake System, Brake Pedal). Then go to Step 11.

NO : Replace the stoplight switch (Refer to Basic Brake System, Brake Pedal). Then go to Step 15.

STEP 11. Check ECM connector B-109 and stoplight switch connector C-32 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 General (Electrical), Harness Connector Inspection). Then go to Step 15.

STEP 12. Check the harness wire between ECM connector B-109 terminal 108 and ground 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 15.

STEP 13. Using scan tool MB991958, check data list item 89: Normally closed brake switch.

1. Connect scan tool MB991958 to the data link connector. Scan Tool Connecting
2. Turn the ignition switch to the "ON" position.
3. Set scan tool MB991958 to data reading mode for auto-cruise control system. Reading Diagnostic Trouble Codes
- 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 General (Body and Chassis), How to Use Troubleshooting/Inspection Service Points - How to Cope with Intermittent Malfunction). Then go to Step 15.

NO : Replace the ECM. When the ECM is replaced, register the encrypted code (Refer to Troubleshooting - ID Code Registration Judgment Table). Then go to Step 15.

STEP 14. Read the diagnostic trouble codes.

1. Disconnect the negative (-) battery terminal, to erase the diagnostic trouble code of the auto-cruise control system.
2. Connect the negative (-) battery cable.
3. Turn the ignition switch to the "ON" position, and press the "ON/OFF" (MAIN) switch to turn the auto-cruise control system to ON (turn on the "CRUISE" indicator light).
4. With the auto-cruise control switches not operated, depress the brake pedal for several seconds, and then read the diagnosis code of the auto-cruise control system. Reading Diagnostic Trouble Codes

Q: Is DTC 22 set?

YES : Replace the ECM. When the ECM is replaced, register the encrypted code (Refer to Troubleshooting - ID Code Registration Judgment Table). Then go to Step 15.

NO : It can be assumed that this malfunction is intermittent (Refer to General (Body and Chassis), How to Use Troubleshooting/Inspection Service Points - How to Cope with Intermittent Malfunction). Then go to Step 15.

STEP 15. Using scan tool MB991958, check data list item 74: Brake light switch and item 89: Normally closed brake switch.

1. Connect scan tool MB991958 to the data link connector. Scan Tool Connecting
2. Turn the ignition switch to the "ON" position.
3. Set scan tool MB991958 to data reading mode for auto-cruise control system. Reading Diagnostic Trouble Codes
- 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.

STEP 16. Read the diagnostic trouble codes.

1. Disconnect the negative (-) battery terminal, and erase the diagnostic trouble code of the auto-cruise control system.
2. Connect the negative (-) battery cable.
3. Turn the ignition switch to the "ON" position, and press the "ON/OFF" (MAIN) switch to turn the auto-cruise control system to ON (turn on the "CRUISE" indicator light).
4. With the auto-cruise control switches not operated, depress the brake pedal for several seconds, and then read the diagnosis code of the auto-cruise control system. Reading Diagnostic Trouble Codes

Q: Is DTC 22 set?

YES : Return to Step 1.

NO : The procedure is complete.