Dtc P0724 Brake Switch B Circuit High

Lexus IS250 IS220d GSE20 ALE20 - A960E AUTOMATIC TRANSMISSION

DESCRIPTION

MONITOR DESCRIPTION

WIRING DIAGRAM

INSPECTION PROCEDURE

READ VALUE OF DATA LIST (STP SIGNAL)

INSPECT STOP LIGHT SWITCH ASSEMBLY

CHECK HARNESS AND CONNECTOR (STOP LIGHT SWITCH ASSEMBLY - ECM)

DTC P0724 Brake Switch "B" Circuit High

DESCRIPTION

The purpose of this circuit is to prevent the engine from stalling while driving in lock-up condition when brakes are suddenly applied.


When the brake pedal is depressed, this switch sends a signal to the ECM. Then the ECM cancels the operation of the lock-up clutch while braking is in progress.

DTC No.DTC Detection ConditionTrouble Area
P0724The stop light switch remains ON even when the vehicle is driven in a STOP (less than 3 km/h (2 mph)) and GO (30 km/h (19 mph) or more) fashion 5 times. (2-trip detection logic).
Short in stop light switch signal circuit
Stop light switch
ECM

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 3 km/h (2 mph)) and go (30 km/h (19 mph) or more) ten times for two driving cycles in order to detect a malfunction.


WIRING DIAGRAM

.


INSPECTION PROCEDURE

1.READ VALUE OF DATA LIST (STP SIGNAL)
  • HINT:
  • Using the intelligent tester Data List allows switch, sensor, actuator and other item values to be read without removing any parts. Reading the Data List early in troubleshooting is one way to shorten labor time.

Turn the engine switch off.

Connect the intelligent tester to the DLC3.

Turn the engine switch on (IG) position.

Turn on the tester.

Select the item "Enter / Powertrain / ECT / Data List".

Follow the instructions on the tester and read the Data List.

  • Standard:
  • ItemMeasurement Item/
    Range (display)    		Normal Condition
    Stop light SWStop light switch Status/
    ON or OFF
    Brake Pedal is depressed: ON
    Brake Pedal is depressed: OFF
  • NOTICE:
  • In the table above, the conditions listed under "Normal Condition" are reference conditions. Do not depend solely on these reference conditions when deciding whether a part is faulty or not.
OK
Go to step 3
NG
2.INSPECT STOP LIGHT SWITCH ASSEMBLY
Dtc P0724 Brake Switch B Circuit High. A960E AUTOMATIC TRANSMISSION. Lexus IS250 IS220d GSE20 ALE20

Remove the stop light switch assembly.

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

  • Standard resistance:
  • Switch positionTester ConnectionSpecified Condition
    Switch pin free1 - 2Below 1 Ω
    Switch pin pushed in↑10 kΩ or higher
    Switch pin free3 - 410 kΩ or higher
    Switch pin pushed in↑Below 1 Ω
NG
REPLACE STOP LIGHT SWITCH ASSEMBLY
OK
3.CHECK HARNESS AND CONNECTOR (STOP LIGHT SWITCH ASSEMBLY - ECM)
Dtc P0724 Brake Switch B Circuit High. A960E AUTOMATIC TRANSMISSION. Lexus IS250 IS220d GSE20 ALE20

Install the stop light switch assembly.

Disconnect the ECM connector.

Measure the voltage according to the value(s) in the table below when the brake pedal is depressed and released.

  • Standard voltage:
  • ConditionTester ConnectionSpecified Condition
    Brake pedal is depressedA6-4 (STP) - Body ground10 to 14 V
    Brake pedal is released↑Below 1 V
NG
REPAIR OR REPLACE HARNESS OR CONNECTOR
OK
REPLACE ECM