What Does P0725 Mean?
The TCM has detected an abnormally high voltage on the torque converter/brake switch B circuit. This circuit provides critical input to the transmission control module for shift scheduling and torque converter clutch operation. The driver may notice harsh or delayed shifting, the transmission remaining in a single gear (limp mode), or the torque converter clutch failing to engage properly.
Common Causes
35%
Faulty brake light switch or torque converter brake switch B (stuck closed or shorted to power)
25%
Short to voltage in the wiring harness between the switch and TCM
20%
Corroded or damaged connector at the TCM or switch causing high resistance feedback
15%
TCM internal circuit failure (high-side driver stuck on)
5%
Misadjusted brake pedal position or switch mounting
Diagnostic Steps
1
Monitor the brake switch B PID in live data while pressing and releasing the brake pedal — the signal should toggle cleanly between high and low states.
2
Use a DVOM to backprobe the brake switch B signal wire at the TCM connector; with the brake released, voltage should be near 0V, and with the brake applied, it should read battery voltage (12–14V). A constant high reading confirms the circuit fault.
3
Inspect the brake light switch at the brake pedal — check for proper adjustment (switch plunger should depress fully when brake is released) and test continuity across the switch terminals in both positions.
4
Trace the wiring harness from the brake/torque converter switch B to the TCM connector, looking for chafed insulation, pinched wires, or shorts to the power bus.
5
If the switch and wiring test normal, swap the TCM with a known-good unit (if available) or send for bench testing to rule out internal driver failure.
Estimated Repair Cost
$50 - $450
Parts + labor, varies by vehicle and location
The TCM has detected an abnormally high voltage on the torque converter/brake switch B circuit. This circuit provides critical input to the transmission control module for shift scheduling and torque converter clutch operation. The driver may notice harsh or delayed shifting, the transmission remain...
The most common cause of P0725 (Torque Converter/Brake Switch B Circuit High) is: Faulty brake light switch or torque converter brake switch B (stuck closed or shorted to power)
Typical repair costs for P0725 range from $50 to $450, depending on the vehicle, location, and whether you do it yourself or go to a shop.
The vehicle may enter limp mode or exhibit unpredictable shifting behavior. Brake input to the TCM may be incorrect, potentially affecting torque converter clutch lockup strategy. Drive cautiously to a shop — avoid heavy towing or aggressive driving.
Start by connecting an OBD2 scanner to read the code and any freeze frame data. Then follow the diagnostic steps specific to P0725 to identify the root cause.
OBDHut Mobile App
Scan codes directly from your car with the OBDHut app.
Coming Soon
Quick Info
Category
Powertrain
System
Automatic Transmission / Torque Converter
Difficulty
Type
Generic (SAE)
Recommended Tools
OBD2 Scanner
A quality scan tool helps you read codes, view live data, and clear faults.
