P0504

2UR-GSE 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 stores the DTC.

HINT
The normal signal conditions are as shown in the table below.





- [OFF] denotes ground potential.
- [ON] denotes battery potential (+B).
- On the Techstream, both the Data List items Stop Light Switch and ST1 are ON when the brake pedal is depressed because the ST1 indication characteristic is opposite to the Stop Light Switch indication.





WIRING DIAGRAM





INSPECTION PROCEDURE

NOTICE:
Inspect the fuses of circuits related to this system before performing the following inspection procedure.

HINT
- Read freeze frame data using the 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.
- Stop light switch conditions can be checked using the Techstream.
(1) Connect the Techstream to the DLC3.
(2) Turn the engine switch on (IG).
(3) Turn the Techstream on.
(4) Enter the following menus: Powertrain / Engine / Data List / All Data / Stop Light Switch and ST1.
(5) Check the Data List indication when the brake pedal is depressed and released.





PROCEDURE

1. READ VALUE USING TECHSTREAM (STP SIGNAL AND ST1- VOLTAGE)

(a) Connect the Techstream to the DLC3.





(b) Turn the engine switch on (IG) and turn the Techstream on.

(c) Enter the following menus: Powertrain / Engine / Data List / Stop Light Switch.

(d) Check the STP signal when the brake pedal is depressed and released.

Standard:





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

Standard Voltage:





NG -- INSPECT STOP LIGHT SWITCH (POWER SOURCE)

OK -- CHECK FOR INTERMITTENT PROBLEMS Check for Intermittent Problems

2. INSPECT STOP LIGHT SWITCH (POWER SOURCE)

(a) Disconnect the stop light switch.





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

Standard Voltage:





(c) Reconnect the stop light switch connector.

NG -- INSPECT FUSE (STOP SW AND IGN FUSE)
OK -- Continue to next step.

3. INSPECT STOP LIGHT SWITCH ASSEMBLY

(a) Inspect the stop light switch assembly Testing and Inspection.

NG -- REPLACE STOP LIGHT SWITCH ASSEMBLY Removal
OK -- Continue to next step.

4. CHECK HARNESS AND CONNECTOR (STOP LIGHT SWITCH - ECM)

(a) Disconnect the stop light switch connector.

(b) Disconnect the ECM connector.

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

Standard Resistance (Check for Open):





Standard Resistance (Check for Short):





(d) Reconnect the stop light switch connector and ECM connector.

NG -- REPAIR OR REPLACE HARNESS OR CONNECTOR (STOP LIGHT SWITCH - ECM)

OK -- REPLACE ECM Removal

5. INSPECT FUSE (STOP SW AND IGN FUSE)

(a) Remove the STOP SW fuse and IGN fuse from the cowl side junction block RH.





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

Standard Resistance:





(c) Reinstall the STOP SW fuse and IGN fuse.

NG -- REPLACE FUSE (STOP SW AND IGN FUSE)

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