DTC P0724: Brake Switch "B" Circuit High: Notes

WARNING: This page is about a different car, the 2022 Subaru WRX. However, it is still accessible from the selected car via links, so may be relevant.

1. -

DTC detecting condition:

Immediately at fault recognition

Trouble symptom:

Gear is not shifted down when climbing a hill or driving down a hill.

Wiring diagram:

Stop light system Ref. to WIRING SYSTEM>STOP LIGHT SYSTEM

Courtesy of SUBARU OF AMERICA, INC.

CAUTION:

Use CHECK BOARD when measuring the TCM terminal voltage and resistance.
After servicing or replacing faulty parts, perform the last step of the basic diagnostic procedure. Ref. to TRANSMISSION (DIAGNOSTICS)>BASIC DIAGNOSTIC PROCEDURE

CHECK STOP LIGHT SWITCH .
1. Turn the ignition switch to OFF.
2. Disconnect the stop light switch connector.
3. Measure the resistance between stop light switch.
  Connector & terminal
  
  (B101) No. 1 - No. 2:
Is the resistance 1 MΩ or more?

Yes : Go to 2.

No : Replace the stop light switch. Ref. to BRAKE>STOP LIGHT SWITCH
CHECK HARNESS .
1. Disconnect the TCM connector.
2. Turn the ignition switch to ON.
3. Measure the voltage between TCM connector and chassis ground.
  Connector & terminal
  
  (B67) No. 29 (+) - Chassis ground (-):
Is the voltage 10 V or more?

Yes : Repair the short circuit of harness.

No : Go to 3.
CHECK INPUT SIGNAL FOR TCM .
1. Connect all connectors.
2. Turn the ignition switch to ON.
3. Using the Subaru Select Monitor, read data of [Stop Light Switch] in the [Data Monitor] of [Transmission]. Ref. to TRANSMISSION (DIAGNOSTICS)>DATA MONITOR
Is [OFF] displayed?

Yes : Current condition is normal. Check for poor contact in connectors or harnesses, and repair the defective part.

No : Go to 4.
CHECK FOR POOR CONTACT .
Is there poor contact in the stop light switch input signal circuit?

Yes : Repair the poor contact.

No : Replace the TCM. Ref. to CONTINUOUSLY VARIABLE TRANSMISSION (TR690)>TRANSMISSION CONTROL MODULE (TCM)