P0504

1UR-FSE ENGINE CONTROL SYSTEM: SFI SYSTEM: P0504: Brake Switch "A" / "B" Correlation
P0504 - Brake Switch "A" / "B" Correlation

DESCRIPTION

The stop light switch is a duplex system that transmits two signals: STP and ST1-. These two signals are used by the ECM to monitor whether or not the brake system is working properly. If the signals, which indicate the brake pedal is being depressed and released, are detected simultaneously, the ECM interprets this as a malfunction in the stop light switch and stores the DTC.

HINT
The normal signal conditions are as shown in the table below.





- [OFF] denotes ground potential.
- [ON] denotes battery potential (+B).
- On the Techstream, both the Data List items Stop Light Switch and ST1 are ON when the brake pedal is depressed because the ST1 indication characteristic is opposite to the Stop Light Switch indication.





CONFIRMATION DRIVING PATTERN





1. Connect the Techstream to the DLC3.

2. Turn the engine switch on (IG) and turn the Techstream on.

3. Clear the DTCs (even if no DTCs are stored, perform the clear DTC procedure) Reading and Clearing Diagnostic Trouble Codes.

4. Turn the engine switch off and wait for 30 seconds.

5. Turn the engine switch on (IG) and turn the Techstream on [A].

6. Depress and release the brake pedal [B].

7. Enter the following menus: Powertrain / Engine / Trouble Codes.

8. Read the DTC [C].

HINT
- If a DTC is output, the system is malfunctioning.
- If a DTC is not output, perform the following procedure.

9. Enter the following menus: Powertrain / Engine / Utility / All Readiness.

10. Input the DTC: P0504.

11. Check the DTC judgment result.





HINT
- If the judgment result shows ABNORMAL, the system has a malfunction.
- If the judgment result shows NORMAL, the system is normal.
- If the judgment result sows INCOMPLETE or UNKNOWN, perform step [B] again.

12. Enter the following menus: Powertrain / Engine / Utility / All Readiness.

13. Check the DTC judgment result.

HINT
- If the judgment result shows ABNORMAL, the system has a malfunction.
- If the judgment result shows NORMAL, the system is normal.

14. If the test result is INCOMPLETE or UNKNOWN and no DTC is output, perform a universal trip and check for permanent DTCs Reading and Clearing Diagnostic Trouble Codes.

HINT
- If a permanent DTC is output, the system is malfunctioning.
- If no permanent DTC is output, the system is normal.

WIRING DIAGRAM





INSPECTION PROCEDURE

NOTICE:
Inspect the fuses of circuits related to this system before performing the following inspection procedure.

HINT
- Read freeze frame data using the Techstream. Freeze frame data records the engine condition when malfunctions are detected. When troubleshooting, freeze frame data can help determine if the vehicle was moving or stationary, if the engine was warmed up or not, if the air-fuel ratio was lean or rich, and other data from the time the malfunction occurred.
- Stop light switch conditions can be checked using the Techstream.
(1) Connect the Techstream to the DLC3.
(2) Turn the engine switch on (IG).
(3) Turn the Techstream on.
(4) Enter the following menus: Powertrain / Engine / Data List / All Data / Stop Light Switch and ST1.
(5) Check the Data List indication when the brake pedal is depressed and released.





PROCEDURE

1. INSPECT STOP LIGHT SWITCH ASSEMBLY

(a) Remove the stop light switch assembly.





(b) Measure the resistance according to the value(s) in the table below.

Standard Resistance:





(c) Reinstall the stop light switch assembly.

NG -- REPLACE STOP LIGHT SWITCH ASSEMBLY Components
OK -- Continue to next step.

2. READ VALUE USING TECHSTREAM (STP SIGNAL AND ST1- VOLTAGE)

(a) Connect the Techstream to the DLC3.





(b) Turn the engine switch on (IG) and turn the Techstream on.

(c) Enter the following menus: Powertrain / Engine / Data List / Stop Light Switch.

(d) Check the STP signal when the brake pedal is depressed and released.

Standard:





(e) Measure the voltage according to the value(s) in the table below.

Standard Voltage:





OK -- CHECK FOR INTERMITTENT PROBLEMS Check For Intermittent Problems
NG -- Continue to next step.

3. CHECK HARNESS AND CONNECTOR (STOP LIGHT SWITCH - ECM)

(a) Disconnect the stop light switch connector.

(b) Disconnect the ECM connector.

(c) Measure the resistance according to the value(s) in the table below.

Standard Resistance (Check for Open):





Standard Resistance (Check for Short):





(d) Reconnect the stop light switch connector and ECM connector.

NG -- REPAIR OR REPLACE HARNESS OR CONNECTOR

OK -- REPLACE ECM Components