P0504

1AR-FE ENGINE CONTROL: 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 2 signals: STP and ST1-. These 2 signals are used by the ECM to monitor whether or not the brake system is working properly. If 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 ignition switch to ON 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 ignition switch off and wait for at least 30 seconds.

5. Turn the ignition switch to ON and turn the Techstream on [A].

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

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

8. Read the Pending DTCs.

HINT
* If a pending DTC is output, the system is malfunctioning.
* If a pending 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 NORMAL, the system is normal.
* If the judgment result shows ABNORMAL, the system has a malfunction.

12. If the test result is INCOMPLETE or UNKNOWN and no pending 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 for circuits related to this system before performing the following inspection procedure.

HINT
* Read freeze frame data using the Techstream. The ECM records vehicle and driving condition information as freeze frame data the moment a DTC is stored. 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 ignition switch to ON.
(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 (TERMINAL VOLTAGE)

(a) Disconnect the stop light switch assembly connector.





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

Standard Voltage:





Text in Illustration





(c) Reconnect the stop light switch assembly connector.

NG -- REPAIR OR REPLACE HARNESS OR CONNECTOR
OK -- Continue to next step.

2. INSPECT STOP LIGHT SWITCH ASSEMBLY

(a) Inspect the stop light switch assembly Testing and Inspection.

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

3. INSPECT ECM (STP AND ST1- VOLTAGE)

(a) Disconnect the ECM connector.





(b) Turn the ignition switch to ON.

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

Standard Voltage:





Text in Illustration





(d) Reconnect the ECM connector.

NG -- REPAIR OR REPLACE HARNESS OR CONNECTOR

OK -- REPLACE ECM Removal