Torque Converter/Brake Switch B Circuit Low
The torque converter clutch (TCC) solenoid receives a control signal through the brake switch circuit. P0719 indicates the PCM detected a low voltage signal on the brake switch B circuit, meaning the brake pedal input signal is not reaching the transmission control module properly. This prevents proper torque converter lockup/unlockup during braking events.
What You Might Notice
- Transmission staying in lockup when braking
- Poor fuel economy due to continuous converter lockup
- Transmission entering limp mode
- Brake lights not functioning properly
- Harsh downshifts or delayed shifts during deceleration
Most Common Causes
- 1
Faulty brake switch
The brake switch contacts may be worn, corroded, or stuck open, preventing the brake signal from reaching the PCM. This is the most common cause of P0719.
- 2
Wiring or connector issues
Broken wires, loose connectors, or corrosion in the brake switch circuit can interrupt the signal path between the brake switch and PCM.
- 3
PCM or transmission control module fault
A malfunctioning PCM or TCM may fail to properly receive or interpret the brake switch signal, even if the switch itself is functioning correctly.
- 4
Brake pedal mechanical issue
A stuck or misaligned brake pedal may not fully depress the switch contacts, resulting in an incomplete signal to the transmission control system.
How to Diagnose It
- 1
Check Faulty brake switch — The brake switch contacts may be worn, corroded, or stuck open, preventing the brake signal from reaching the PCM. This is the most common cause of P0719.
- 2
Check Wiring or connector issues — Broken wires, loose connectors, or corrosion in the brake switch circuit can interrupt the signal path between the brake switch and PCM.
- 3
Check PCM or transmission control module fault — A malfunctioning PCM or TCM may fail to properly receive or interpret the brake switch signal, even if the switch itself is functioning correctly.
- 4
Check Brake pedal mechanical issue — A stuck or misaligned brake pedal may not fully depress the switch contacts, resulting in an incomplete signal to the transmission control system.
How to Fix It
- 1
Replace brake switch
Locate and replace the brake switch (typically mounted on the brake pedal assembly). Ensure the new switch is properly adjusted and making full contact when the brake pedal is depressed.
- 2
Inspect and repair wiring
Check the brake switch wiring harness and connectors for corrosion, breaks, or loose connections. Repair or replace damaged wiring and clean corroded connectors.
- 3
Check brake pedal operation
Verify the brake pedal moves freely and fully depresses without binding. Adjust pedal if misaligned or lubricate if sticking. Ensure the switch is contacted fully when brakes are applied.
- 4
Reprogram or replace PCM/TCM
If wiring and brake switch are confirmed functional, the PCM or transmission control module may need reprogramming or replacement. This requires professional diagnostic equipment.
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