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DTC P0504: Malfunction of the Stoplight Switch System.
 
 

 
 
OPERATION
  • For the stoplight switch, two switches, a stoplight switch for the stoplight illumination and a brake switch exclusively for the cruise control system, are incorporated to improve the reliability.
  • As for the stoplight switch, when the brake pedal is depressed/released, the stoplight switch ON/OFF signal is transmitted from the ETACS-ECU to the ECM via CAN bus line.
  • As for the brake switch, the ECM 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 ECM connector terminal BRK changes. According to this change, the ECM judges the state of the brake switch.
 
 
DIAGNOSTIC TROUBLE CODE SET CONDITIONS
Check Condition
  • The cruise control display screen is displayed.
Judgment Criteria
  • Open/short in stoplight switch circuit.
  • Open circuit in the brake switch circuit (between ECM connector terminal BRK and ground).
  • 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 stoplight switch.
  • Malfunction of the ETACS-ECU.
  • Malfunction of the ECM.
 
 
DIAGNOSIS
caution
  • If there is any problem in the CAN bus lines, an incorrect DTC 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. Using scan tool (M.U.T.-IIISE), diagnose CAN bus line.
(1)
cautionTo prevent damage to scan tool (M.U.T.-IIISE), always turn the ignition switch to the "LOCK" (OFF) position before connecting or disconnecting scan tool (M.U.T.-IIISE).
Connect scan tool (M.U.T.-IIISE). Refer to "How to connect the Scan Tool (M.U.T.-IIISE) ."
(2) Turn the ignition switch to the "ON" position.
(3) Diagnose the CAN bus line [Refer to GROUP 54C - Explanation About The Scan Tool (M.U.T.-IIISE) CAN Bus Diagnostics ].
(4) Turn the ignition switch to the "LOCK" (OFF) position.
Is the check result normal?
Go to Step 2.
Repair the CAN bus lines (Refer to GROUP 54C - Diagnosis, CAN Bus Diagnostics Table ).
 
STEP 2. Using scan tool (M.U.T.-IIISE), check the data list.
Check the following data list (Refer to ].
  • Item No.74: Stoplight switch
Is the check result normal?
Go to Step 6.
Go to Step 3.
 
STEP 3. Check the stoplight operation.
Check the stoplight operation.
OK:
  • Brake pedal depressed: Stoplight will illuminate
  • Brake pedal not depressed: Stoplight does not illuminate
Is the check result normal?
Go to Step 4.
Check the stoplight system (Refer to GROUP 54A - Rear Combination Light, Symptom Procedures, The stoplights do not illuminate or go out normally ).
 
STEP 4. Using scan tool (M.U.T.-IIISE), check the ETACS data list.
Using scan tool (M.U.T.-IIISE), check the ETACS data list (Refer to GROUP 54A - ETACS, Diagnosis, Data List Reference Table ).
  • Item No.113: Stoplight switch
Is the check result normal?
Go to Step 5.
Replace the ETACS-ECU (Refer to GROUP 54A - ETACS, ETACS-ECU ).
 
STEP 5. Using scan tool (M.U.T.-IIISE), check the data list.
Check the following data list (Refer to ).
  • Item No.74: Stoplight switch
Is the check result normal?
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 ).
Replace the ECM (Refer to GROUP 13A - ECM ).
 
STEP 6. Using scan tool (M.U.T.-IIISE), check the data list.
Check the following data list (Refer to ).
  • Item No.89: Normally closed brake switch
Is the check result normal?
Go to Step 11.
Go to Step 7.
 
STEP 7. Check of open circuit, short circuit, and damage in BRK line between ECM connector and stoplight switch connector.
Is the check result normal?
Go to Step 8.
Repair the connector(s) or wiring harness.
 
STEP 8. Check of open circuit, and damage in ground line between stoplight switch connector and body ground.
Is the check result normal?
Go to Step 9.
Repair the connector(s) or wiring harness.
 
STEP 9. Check the stoplight switch.
Refer to GROUP 35A - Brake Pedal, Inspection, Stoplight Switch Check .
Is the check result normal?
Go to Step 10.
Replace the stoplight switch (Refer to GROUP 35A - Brake Pedal ).
 
STEP 10. Using scan tool (M.U.T.-IIISE), check the data list.
Check the following data list (Refer to ).
  • Item No.89: Brake switch
Is the check result normal?
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 ).
Replace the ECM (Refer to GROUP 13A - ECM ).
 
STEP 11. Using scan tool (M.U.T.-IIISE), check the DTC.
(1) Use the scan tool (M.U.T.-IIISE), erase the DTC 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 display screen is turned on).
(3) With the cruise control switch not operated, depress the brake pedal for several seconds, and then read the DTC of the cruise control system (Refer to ).
Is DTC P0504 set?
Replace the ECM (Refer to GROUP 13A - ECM ).
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 ).