DTC P0719: Brake Switch "B" Circuit Low: 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 M/B FUSE (NO. 3) .
1. Turn the ignition switch to OFF.
2. Remove the M/B fuse (No. 3).
3. Check the fuse.
Is the check result OK?

Yes : Go to 2.

No : Replace the M/B fuse (No. 3). If the new fuse (No. 3) has blown out easily, repair the short circuit of harness between the fuse (No. 3) and stop light switch.
CHECK HARNESS .
1. Turn the ignition switch to OFF.
2. Disconnect the TCM connector.
3. Disconnect the stop light switch connector.
4. Measure the resistance between TCM connector and stop light switch connector.
  Connector & terminal
  
  (B67) No. 29 - (B101) No. 2:
Is the resistance less than 1 Ω?

Yes : Go to 3.

No : Repair the open circuit of harness.
CHECK HARNESS .
Measure the resistance between the stop light switch connector and M/B fuse (No. 3).

Connector & terminal

(B101) No. 1 - (M/B fuse) No. 3:

Is the resistance less than 1 Ω?

Yes : Go to 4.

No : Repair the open circuit of harness.
CHECK INPUT SIGNAL FOR TCM .
1. Install the fuse (No. 3).
2. Connect the stop light switch connector.
3. Depress the brake pedal.
4. Measure the voltage between TCM connector and chassis ground.
  Connector & terminal
  
  (B67) No. 29 (+) - Chassis ground (-):
Is the voltage 10 V or more?

Yes : Go to 5.

No : Replace the stop light switch. Ref. to BRAKE>STOP LIGHT SWITCH
CHECK INPUT SIGNAL FOR TCM .
1. Connect the TCM connector.
2. With brake pedal depressed, read the data of [Stop Light Switch] in the [Data Monitor] of [Transmission] using Subaru Select Monitor. Ref. to TRANSMISSION (DIAGNOSTICS)>DATA MONITOR
Is [ON] displayed?

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

No : Go to 6.
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)