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



PROBABLE CAUSES



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 terminal BRK 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 terminal BRK 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 <standard meter> or the cruise control display screen is displayed <high contrast meter>.
Judgement Criteria
  • Open/short in stop lamp switch circuit.
  • Open circuit in the brake switch circuit (between engine-ECU connector terminal BRK and earth).
  • Malfunction of CAN bus line.

PROBABLE CAUSES



  • Malfunction of CAN bus system.
  • Damaged harness or connector.
  • Malfunction of the fuse No.14.
  • Malfunction of the stop lamp switch.
  • 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 (Refer to data list reference table ).

  • Item 74: 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 2: The stop lamps do not illuminate or go out normally ). Then go to Step 11.

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: Stop lamp 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 11.

STEP 5. Check the data list.


Using M.U.T.-III, check the data list (Refer to data list reference table ).

  • Item 74: Stop lamp switch

Q. Is the check result normal?

Go to Step 6.
Replace the engine-ECU (Refer to GROUP 13A - Engine-ECU <4B1>, GROUP 13C - Engine-ECU <4J1>). Then go to Step 11.

STEP 6. Check the data list.


Using M.U.T.-III, check the data list (Refer to data list reference table ).

  • Item 89: Brake switch

Q. Is the check result normal?

Go to Step 10.
Go to Step 7.

STEP 7. Check the harness wire between engine-ECU connector terminal BRK and stop lamp switch connector, and between stop lamp switch connector and earth.



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

Q. Is the check result normal?

Go to Step 8.
Repair connector or damaged harness wire. Then go to Step 11.

STEP 8. Check the stop lamp switch.


Refer to GROUP 35A - Brake Pedal, Inspection, Stop Lamp Switch Check .

Q. Is the check result normal?

Go to Step 9.
Replace the stop lamp switch (Refer to GROUP 35A - Brake Pedal ). Then go to Step 11.

STEP 9. Check the data list.


Using M.U.T.-III, check the data list (Refer to data list reference table ).

  • Item 89: Brake switch

Q. Is the check result normal?

Go to Step 10.
Replace the engine-ECU (Refer to GROUP 13A - Engine-ECU <4B1>, GROUP 13C - Engine-ECU <4J1>). Then go to Step 11.

STEP 10. 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 cruise control ON/OFF switch to turn the cruise control system to ON (the cruise control indicator lamp <standard meter> or the cruise control display screen <high contrast meter> is turned on).
(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 (Refer to ).

Q. Is diagnosis code No. P0504 set?

Replace the engine-ECU (Refer to GROUP 13A - Engine-ECU <4B1>, GROUP 13C - Engine-ECU <4J1>). Then go to Step 11.
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 11. Check the data list.


Using M.U.T.-III, check the data list (Refer to data list reference table ).

  • Item 74: Stop lamp switch
  • Item 89: Brake switch

Q. Is the check result normal?

Go to Step 12.
Return to Step 2.

STEP 12. 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 cruise control ON/OFF switch to turn the cruise control system to ON (the cruise control indicator lamp <standard meter> or the cruise control display screen <high contrast meter> is turned on).
(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 (Refer to ).

Q. Is diagnosis code No. P0504 set?

Return to Step 1.
The procedure is complete.