P0504

2UZ-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.









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.

PROCEDURE

1. CHECK OPERATION OF STOP LIGHT
(a) Check if the stop lights turn on and off normally when the brake pedal is depressed and released.
OK:
Stop light turns ON when brake pedal is depressed.
NG -- REPAIR OR REPLACE STOP LIGHT SWITCH CIRCUIT
OK -- Continue to next step.
2. INSPECT STOP LIGHT SWITCH ASSEMBLY
(a) Check the stop light switch Testing and Inspection.
NG -- REPLACE STOP LIGHT SWITCH ASSEMBLY
OK -- Continue to next step.
3. READ VALUE USING TECHSTREAM (STP SIGNAL AND ST1- VOLTAGE)




(a) Connect the Techstream to the DLC3.
(b) Turn the ignition switch ON.
(c) Enter the following menus: Powertrain / Engine and ECT / All Data / 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 HARNESS AND CONNECTOR (STOP LIGHT SWITCH - ECM)




(a) Disconnect the S17 stop light switch connector.
(b) Disconnect the E9 ECM connector.
(c) Measure the resistance between the wire harness side connectors.
Standard resistance (Check for open):






Standard resistance (Check for short):





(d) Reconnect the ECM connector.
(e) Reconnect the stop light switch connector.
NG -- REPAIR OR REPLACE HARNESS OR CONNECTOR
OK -- REPLACE ECM