What Does P0720 Mean?
The torque converter or brake switch B circuit is reading a low voltage signal. On many vehicles, this code relates to the output speed sensor circuit malfunction or the torque converter/brake switch circuit B input being stuck low. The TCM uses this input to determine braking events for shift strategy and torque converter lockup control. The driver may experience incorrect torque converter lockup behavior or the transmission not downshifting properly when braking.
Common Causes
30%
Faulty brake switch or torque converter switch stuck in the closed/low position
25%
Short to ground in the switch B signal circuit
20%
Misadjusted brake pedal switch not releasing properly
15%
Corroded or damaged connector at the switch or TCM
10%
TCM internal input circuit fault
Diagnostic Steps
1
Monitor the brake switch B status PID in live data. Press and release the brake pedal — the scan tool should show clear on/off transitions. A stuck-low reading confirms the fault.
2
Inspect the brake switch at the brake pedal bracket. Check adjustment — the switch should fully release when the pedal is up. Many switches are adjustable by rotating or repositioning.
3
Disconnect the switch connector and check if the scan tool reading changes. If it goes high, the switch is stuck closed. If it stays low, the wiring is shorted to ground.
4
Measure continuity across the switch terminals with the pedal up (should be open) and pedal pressed (should be closed). Compare to manufacturer spec for normally-open vs. normally-closed design.
5
Check for voltage at the switch connector with KOEO. Verify proper battery voltage or reference voltage is present on the supply wire.
Estimated Repair Cost
$30 - $250
Parts + labor, varies by vehicle and location
The torque converter or brake switch B circuit is reading a low voltage signal. On many vehicles, this code relates to the output speed sensor circuit malfunction or the torque converter/brake switch circuit B input being stuck low. The TCM uses this input to determine braking events for shift strat...
The most common cause of P0720 (Torque Converter/Brake Switch B Circuit Low) is: Faulty brake switch or torque converter switch stuck in the closed/low position
Typical repair costs for P0720 range from $30 to $250, depending on the vehicle, location, and whether you do it yourself or go to a shop.
The TCM may not properly release the torque converter clutch when braking, which can cause the engine to stall. Additionally, brake lights may be affected if the same switch circuit controls them. Have this repaired promptly as it can affect both drivability and safety.
Start by connecting an OBD2 scanner to read the code and any freeze frame data. Then follow the diagnostic steps specific to P0720 to identify the root cause.
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Quick Info
Category
Powertrain
System
Transmission
Difficulty
Type
Generic (SAE)
Recommended Tools
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