Engine Control System - SFI System

2GR-FE ENGINE CONTROL SYSTEM: SFI SYSTEM: P0504: Brake Switch "A" / "B" Correlation

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

DTC P0724 - Brake Switch "B" Circuit High

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.









MONITOR DESCRIPTION

This DTC indicates that the stop light switch remains on. When the stop light switch remains ON during "stop and go" driving, the ECM interprets this as a fault in the stop light switch and the MIL comes on and the ECM stores the DTC. The vehicle must stop (less than 1.86 mph (3 km/h)) and go (18.65 mph (30 km/h) or more) 5 times in two driving cycles in order to detect a malfunction.

MONITOR STRATEGY





TYPICAL ENABLING CONDITIONS





TYPICAL MALFUNCTION THRESHOLDS





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 Freeze Frame Data.

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.
OK:





(e) Enter the following menus: Powertrain / Engine / Data List / ST1.
(f) Check the ST1 signal when the brake pedal is depressed and released.
OK:






OK -- CHECK FOR INTERMITTENT PROBLEMS
NG -- Continue to next step.
2. INSPECT STOP LIGHT SWITCH ASSEMBLY




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





(c) Reinstall the stop light switch assembly.
NG -- REPLACE STOP LIGHT SWITCH ASSEMBLY
OK -- Continue to next step.
3. CHECK ECM (STP, ST1 - VOLTAGE)




(a) Disconnect the A10 ECM connector.
(b) Turn the engine switch on (IG).
(c) Measure the voltage according to the value(s) in the table below.
Standard voltage:






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