Code No.P0504: Malfunction of the Stop Lamp Switch System.


OPERATION



  • For the stop lamp switch, two switches, a stop lamp switch for the stop lamp illumination and a brake switch exclusively for the cruise control system, are incorporated to improve the reliability.
  • As for the stop lamp switch, when the brake pedal is depressed/released, the stop lamp switch ON/OFF signal is transmitted from the ETACS-ECU to the engine-ECU via CAN bus line.
  • As for the brake switch, the engine-ECU connector B-10 terminal No.126 monitor the state of the brake switch. The brake switch turn ON/OFF when the brake pedal is depressed/released, and the input signal to the engine-ECU connector B-10 terminal No.126 changes. According to this change, the engine-ECU judges the state of the brake switch.

DIAGNOSIS CODE SET CONDITIONS


Check Condition
  • The cruise control indicator lamp illuminates.
Judgement Criteria
  • Open/short in stop lamp switch circuit.
  • Open circuit in the brake switch circuit (between engine-ECU connector B-10 terminal No.126 and earth).
  • Malfunction of CAN bus line.

PROBABLE CAUSES



  • Malfunction of CAN bus system.
  • Damaged harness or connector.
  • Malfunction of the fuse No.2 at the ETACS-ECU.
  • Malfunction of the stop lamp switch.
  • Malfunction of the stop lamp relay.
  • Malfunction of the ETACS-ECU.
  • Malfunction of the engine-ECU.

DIAGNOSIS PROCEDURE
caution
  • If there is any problem in the CAN bus lines, an incorrect diagnosis code may be set. Prior to this diagnosis, diagnose the CAN bus lines.
  • Before replacing the ECU, ensure that the CAN bus lines is normal.

STEP 1. Check the CAN bus system diagnosis.
Using M.U.T.-III, perform CAN bus diagnosis (Refer to GROUP 54C - Explanation About The M.U.T-III Can Bus Diagnostics ).

Q. Is the check result satisfactory?
Go to Step 2.
Repair the CAN bus lines (Refer to GROUP 54C - Troubleshooting, Can Bus Diagnostic Table ). Then go to Step 12.

STEP 2. Check the data list.
Using M.U.T.-III, check the data list.

  • Item 135: Stop lamp switch.

Q. Is the check result normal?
Go to Step 6.
Go to Step 3.

STEP 3. Check the stop lamp operation.
Check the stop lamp operation.
OK:

    Brake pedal depressed: Stop lamp will illuminate
    Brake pedal not depressed: Stop lamp does not illuminate

Q. Is the check result normal?
Go to Step 4.
Check the stop lamp system (Refer to GROUP 54A - Rear Combination Lamp, Symptom Procedures, Inspection Procedure No.3 ). Then go to Step 12.

STEP 4. Check the ETACS system data list.
Using M.U.T.-III, check the ETACS system data list (Refer to GROUP 54A - ETACS, Troubleshooting, data list reference table ).

  • Item 290: Brake switch

Q. Is the check result normal?
Go to Step 5.
Replace the ETACS-ECU (Refer to GROUP 54A - ETACS, ETACS-ECU ). Then go to Step 12.

STEP 5. Check the data list.
Using M.U.T.-III, check the data list.

  • Item 135: Stop lamp switch.

Q. Is the check result normal?
Go to Step 6.
Replace the engine-ECU (Refer to GROUP 13B - Engine-ECU ). Then go to Step 12.

STEP 6. Check the data list.
Using M.U.T.-III, check the data list.

  • Item 134: Brake switch.

Q. Is the check result normal?
Go to Step 11.
Go to Step 7.

STEP 7. Connectors check: B-10 engine-ECU connector and stop lamp switch connector.

Q. Is the check result normal?
Go to Step 8.
Repair or replace the damaged connector. Then go to Step 12.

STEP 8. Check the harness wire between engine-ECU connector B-10 terminal No.126 and stop lamp switch connector terminal No.3, and between stop lamp switch connector terminal No.4 and earth.

  • Check harness wire for open/short circuit and damage.

Q. Is the check result normal?
Go to Step 9.
Repair the damaged harness wire. Then go to Step 12.

STEP 9. Check the stop lamp switch.
Refer to GROUP 35A - Brake Pedal, Inspection .

Q. Is the check result normal?
Go to Step 10.
Replace the stop lamp switch (Refer to GROUP 35A - Brake Pedal ). Then go to Step 12.

STEP 10. Check the data list.
Using M.U.T.-III, check the data list.

  • Item 134: Brake switch.

Q. Is the check result normal?
Go to Step 11.
Replace the engine-ECU (Refer to GROUP 13B - Engine-ECU ). Then go to Step 12.

STEP 11. Read the diagnosis code.
(1)Use the M.U.T.-III, erase the diagnosis code of the cruise control system.
(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 control indicator lamp).
(3)With the cruise control switches not operated, depress the brake pedal for several seconds, and then read the diagnosis code of the cruise control system.

Q. Is diagnosis code No.P0504 set?
Replace the engine-ECU (Refer to GROUP 13B - Engine-ECU ). Then go to Step 12.
It can be assumed that this malfunction is intermittent (Refer to GROUP 00 - How to Use Troubleshooting/Inspection Service Points, How to Cope with Intermittent Malfunction ).

STEP 12. Check the data list.
Using M.U.T.-III, check the data list.

  • Item 134: Brake switch.
  • Item 135: Stop lamp switch.

Q. Is the check result normal?
Go to Step 13.
Return to Step 2.

STEP 13. Read the diagnosis code.
(1)Use the M.U.T.-III, erase the diagnosis code of the cruise control system.
(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 control indicator lamp).
(3)With the cruise control switches not operated, depress the brake pedal for several seconds, and then read the diagnosis code of the cruise control system.

Q. Is diagnosis code No.P0504 set?
Return to Step 1.
The procedure is complete.