DTC 22
DTC 22: Stoplight Switch SystemStoplight Switch System Circuit Part 1:
Stoplight Switch System Circuit Part 2:
CIRCUIT OPERATION
When the brake pedal is depressed, the battery positive voltage is applied to the ECM (terminal 108), and the signal is transmitted from the ETACS-ECU to the ECM via CAN bus line.
DTC SET CONDITIONS
Check Condition
The "CRUISE" indicator light illuminates.
Judgement Criteria
Short or open 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 the stoplight switch.
Damaged harness or connector.
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.
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 Diagnosis - CAN Bus Diagnostics Chart). Then go to Step 15.
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.
2. Turn the ignition switch to the "ON" position.
3. Set scan tool MB991958 to data reading mode for auto-cruise control system.
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 the ETACS system data list item 290: Brake light switch.
1. Connect scan tool MB991958 to the data link connector.
2. Turn the ignition switch to the "ON" position.
3. Set scan tool MB991958 to data reading mode for ETACS system(Diagnosis - 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 Diagnosis - ID Code Registration Necessity 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 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 Brake Pedal). Then go to Step 6.
NO: Replace the stoplight switch (Refer to Brake Pedal). Then go to Step 15.
STEP 6. 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 7.
NO: Repair or replace the damaged components. 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 the ETACS system data list item 290: Brake light switch.
1. Connect scan tool MB991958 to the data link connector.
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: It can be assumed that this malfunction is intermittent.
NO: Replace the ETACS-ECU (Refer to ETACSECU). Then go to Step 15.
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.
2. Turn the ignition switch to the "ON" position.
3. Set scan tool MB991958 to data reading mode for auto-cruise control system.
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 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 Brake Pedal). Then go to Step 11.
NO: Replace the stoplight switch (Refer to Brake Pedal). Then go to Step 15.
STEP 11. 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 12.
NO: Repair or replace the damaged components. Then go to Step 15.
STEP 12. Check the harness wire between ECM connector B-11 terminal 108 and ground 3 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 the data list item 89: Normally closed brake switch.
1. Connect scan tool MB991958 to the data link connector.
2. Turn the ignition switch to the "ON" position.
3. Set scan tool MB991958 to data reading mode for auto-cruise control system.
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.
NO: Replace the ECM. When the ECM is replaced, register the encrypted code (Refer to Diagnosis - ID Code Registration Necessity Judgment Table). Then go to Step 15.
STEP 14. Read the diagnostic trouble codes.
1. Erase diagnostic trouble code.
2. Turn the ignition switch to the "ON" position.
3. Turn the "ON/OFF" switch to the "ON" position (turn on the "CRUISE" indicator lamp).
4. Press the brake pedal for 2 second or more, and release.
5. Read the diagnostic trouble codes.
Q: Is DTC P22 set?
YES: Replace the ECM. When the ECM is replaced, register the encrypted code (Refer to Diagnosis - ID Code Registration Necessity Judgment Table). Then go to Step 15.
NO: It can be assumed that this malfunction is intermittent.
STEP 15. Read the diagnostic trouble codes.
1. Erase diagnostic trouble code.
2. Turn the ignition switch to the "ON" position.
3. Turn the "ON/OFF" switch to the "ON" position (turn on the "CRUISE" indicator lamp).
4. Press the brake pedal for 2 second or more, and release.
5. Read the diagnostic trouble codes.
Q: Is DTC P22 set?
YES: Return to Step 1.
NO: The procedure is complete.