P0719
Torque Converter/Brake Switch "B" Circuit Low
Get Your FREE AI Diagnostic Report
Enter your vehicle for a personalized diagnosis for code P0719
The P0719 code indicates a low-voltage condition on the 'B' circuit of the brake switch/torque converter control circuit. This brake switch signal is used by the PCM not only to operate the brake lights but also to control the torque converter clutch lockup and, on many vehicles, the cruise control system. When the PCM sees an abnormally low signal, it can't properly manage these systems.
The most noticeable symptom is often related to the torque converter clutch. If the TCC doesn't release when you brake, the engine may stall as you come to a stop — similar to what happens with a manual transmission if you don't press the clutch pedal. Conversely, if the TCC won't engage, you'll notice reduced fuel economy at highway speeds. Your brake lights may also malfunction, which is a safety hazard, and cruise control may stop working.
The good news is that this is usually one of the cheapest and easiest transmission-related codes to fix. The brake light switch is located at the top of the brake pedal arm, inside the vehicle, and typically costs $5–$40. Before replacing it, check for blown fuses and burned-out brake light bulbs — these simple issues can trigger the code. If the switch looks good, inspect the wiring between the switch and the PCM for shorts. This is very DIY-friendly and doesn't require getting under the vehicle.
Severity
Symptoms
- •Brake lights stay on constantly or don't work at all
- •Vehicle stalls when coming to a complete stop
- •Cruise control doesn't work or won't disengage
- •Torque converter clutch won't lock up or won't release
- •Erratic transmission shifting patterns
- •Check engine light illuminated
Likely Causes
The brake light switch has two circuits — the 'B' circuit controls the brake lamp signal to the PCM/TCM. A faulty switch can send an incorrect low-voltage signal, confusing the transmission's torque converter clutch control.
If the brake light circuit has a blown fuse or burned-out bulbs, the feedback voltage that the PCM monitors on the 'B' circuit will read low, triggering this code.
A short to ground in the wiring between the brake switch and the PCM pulls the circuit voltage low, mimicking a constant brake-off or faulty switch condition.
If the brake switch is not properly positioned relative to the brake pedal, it may not activate the 'B' circuit correctly, causing it to read low even when the brakes are applied.
Estimated Cost
Professional Repair
Includes parts + labor
Common Fixes
- Replace the brake light switch
- Replace blown brake light fuse
- Adjust the brake light switch position
- Replace burned-out brake light bulbs
- Repair shorted wiring in the brake switch circuit