P0504

2AZ-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 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 the Techstream.









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) DTC Check / Clear.

4. Turn the ignition switch off.

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 and ECT / Utility / All Readiness.

8. Input the DTC: P0504.

9. Check the DTC judgment result [C].





HINT
If the judgment result shows ABNORMAL, the system has a malfunction.

10. If the test result is UNKNOWN, enter the following menus: Powertrain / Engine and ECT / Trouble Codes / Pending.

11. Read Pending DTCs.

HINT
If a pending DTC is output, the system is malfunctioning.

12. If the test result is INCOMPLETE or UNKNOWN and no pending DTC is output, perform a universal trip and check for permanent DTCs DTC Check / Clear.

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

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 be helpful in determining whether the vehicle was running or stopped, whether the engine was warmed up or not, whether the air fuel ratio was lean or rich, as well as other data recorded at the time of a malfunction.
- 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 Techstream on.
(4) Enter the following menus: Powertrain / Engine and ECT / 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 Components
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 Components

4. INSPECT FUSES (STOP AND IGN FUSES)





(a) Remove the STOP and IGN fuses from the driver side junction block.

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

Standard Resistance:





(c) Reinstall the STOP and IGN fuses.

NG -- REPLACE FUSE (STOP AND/OR IGN FUSE)

OK -- REPAIR OR REPLACE HARNESS OR CONNECTOR (BATTERY - STOP LIGHT SWITCH)