P0504

2AZ-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 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 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 intelligent tester.









WIRING DIAGRAM





INSPECTION PROCEDURE
HINT: Read freeze frame data using the intelligent tester. 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.

PROCEDURE

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





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






NG -- REPLACE STOP LIGHT SWITCH
OK -- Continue to next step.
3. READ VALUE USING INTELLIGENT TESTER (STP SIGNAL AND ST1 - VOLTAGE)





(a) Connect the intelligent tester to the DLC3.
(b) Turn the ignition switch to the ON position and turn the tester on.
(c) Enter the following menus: DIAGNOSIS / ENHANCED OBD II / DATA LIST / ALL / STOP LIGHT SW.
(d) Check the STP signal when the brake pedal is depressed and released.
Standard operation:





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






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





(a) Disconnect the S8 stop light switch connector.





(b) Disconnect the E4 and E5 ECM connectors.
(c) Measure the resistance according to the value(s) in the table below.
Standard resistance:






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