P0504

3UZ-FE ENGINE CONTROL SYSTEM: SFI SYSTEM: P0504: Brake Switch "A" / "B" Correlation

DTC P0504 - Brake Switch "A" / "B" Correlation

DESCRIPTION

In addition to turning on the stop lights, the stop light switch signals are used for a variety of engine, transmission and suspension functions. The stop light switch is designed with 2 complementary signal outputs, STP and ST1-. The ECM analyzes these signal outputs to detect malfunctions in the stop light switch.





HINT: Normal condition is as shown in the table below. The signals can be read using the Techstream.





WIRING DIAGRAM





INSPECTION PROCEDURE

PROCEDURE

1. CHECK STOP LIGHT SWITCH
(a) Check that the stop lights turn on and off normally when the brake pedal is depressed and released.
NG -- REPAIR OR REPLACE STOP LIGHT SWITCH
OK -- Continue to next step.
2. INSPECT STOP LIGHT SWITCH




(a) Disconnect the S10 stop light switch.
(b) Measure the resistance of the switch.
Standard resistance:






NG -- REPLACE STOP LIGHT SWITCH
OK -- Continue to next step.
3. READ VALUE USING TECHSTREAM (STOP LIGHT SWITCH)




(a) Connect the Techstream to the DLC3.
(b) Turn the ignition switch ON.
(c) Enter the following menus: Powertrain / Engine and ECT / Data List / Stop Light Switch.
(d) Confirm the stop light switch status when the brake pedal is depressed and released.
OK:





(e) Measure the voltage of the ECM when the brake pedal is depressed and released.
Standard voltage:






OK -- CHECK FOR INTERMITTENT PROBLEMS
NG -- Continue to next step.
4. CHECK WIRE HARNESS (STOP LIGHT SWITCH - ECM)




(a) Disconnect the S10 stop light switch connector.
(b) Disconnect the E5 and E6 ECM connectors.
(c) Measure the resistance of the wire harness side connectors.
Standard resistance:






NG -- REPAIR OR REPLACE HARNESS AND CONNECTOR
OK -- REPLACE ECM