P0504

2ZR-FE ENGINE CONTROL SYSTEM: SFI SYSTEM: P0504: Brake Switch "A" / "B" Correlation

DTC 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 sets the DTC.
HINT: The normal conditions are as shown in the table below. The signals can be read using a Techstream.









WIRING DIAGRAM





INSPECTION PROCEDURE
HINT:
- Read freeze frame data using a 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.
- STP signal conditions can be checked using the Techstream.
1. Connect the Techstream to the DLC3.
2. Turn the ignition switch to ON.
3. Turn the tester ON.
4. Select the following menu items: Powertrain / Engine and ECT / All Data / Stop Light Switch.
5. Check the STP signal when the brake pedal is depressed and released.





PROCEDURE

1. INSPECT STOP LIGHT SWITCH (TERMINAL VOLTAGE)





(a) Disconnect the stop light switch connector.
(b) Measure the voltage according to the value(s) in the table below.
Standard voltage:





(c) Reconnect the stop light switch connector.
NG -- INSPECT FUSES (STOP AND IGN FUSES)
OK -- Continue to next step.
2. INSPECT STOP LIGHT SWITCH





(a) Remove the stop light switch.
(b) Measure the resistance according to the value(s) in the table below.
Standard resistance:





(c) Reinstall the stop light switch.
NG -- REPLACE STOP LIGHT SWITCH
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:





(d) Reconnect the ECM connector.
NG -- REPAIR OR REPLACE HARNESS OR CONNECTOR
OK -- REPLACE ECM
4. INSPECT FUSES (STOP AND IGN FUSES)





(a) Remove the STOP and IGN fuses from the main body ECU.
(b) Measure the resistance according to the value(s) in the table below.
Standard resistance:





(c) Reinstall the STOP and IGN fuses.
NG -- CHECK FOR SHORTS IN ALL HARNESSES AND CONNECTORS CONNECTED TO FUSE AND REPLACE FUSE
OK -- REPAIR OR REPLACE HARNESS OR CONNECTOR (BATTERY - STOP LIGHT SWITCH)