Torque Converter/Brake Switch B Circuit High
P0724 indicates the brake switch circuit B is reading higher than expected voltage, preventing the PCM from properly detecting brake pedal depression. This disrupts torque converter lockup disengagement, which can cause transmission overheating and damage if left unaddressed. The transmission may enter limp mode to protect itself.
What You Might Notice
- Check Engine Light illuminated
- Transmission operating in limp mode with reduced power
- Torque converter not unlocking properly during braking
- Harsh or delayed transmission shifts
- Increased transmission temperature and fluid degradation
Most Common Causes
- 1
Faulty brake switch
The brake switch contacts may be stuck closed or failing to open properly, sending a continuous high signal to the PCM regardless of pedal position.
- 2
Corroded or damaged wiring
Corrosion, breaks, or shorts in the brake switch circuit wiring can cause incorrect voltage readings at the PCM connector.
- 3
Poor connector contact
Loose, corroded, or improperly seated connectors at the brake switch or PCM can prevent proper signal transmission and create high resistance.
- 4
PCM or transmission control module failure
A malfunctioning PCM or TCM circuit may misinterpret the brake switch signal voltage, though this is less common than switch or wiring issues.
How to Diagnose It
- 1
Check Faulty brake switch — The brake switch contacts may be stuck closed or failing to open properly, sending a continuous high signal to the PCM regardless of pedal position.
- 2
Check Corroded or damaged wiring — Corrosion, breaks, or shorts in the brake switch circuit wiring can cause incorrect voltage readings at the PCM connector.
- 3
Check Poor connector contact — Loose, corroded, or improperly seated connectors at the brake switch or PCM can prevent proper signal transmission and create high resistance.
- 4
Check PCM or transmission control module failure — A malfunctioning PCM or TCM circuit may misinterpret the brake switch signal voltage, though this is less common than switch or wiring issues.
How to Fix It
- 1
Inspect and replace brake switch
Test the brake switch for proper open/closed operation using a multimeter. If the switch remains closed or shows abnormal resistance, replace it with an OEM or quality aftermarket switch.
- 2
Clean and inspect wiring and connectors
Examine all brake switch circuit wiring for corrosion, damage, or breaks. Clean connector pins with electrical cleaner and apply dielectric grease. Reseat all connections firmly.
- 3
Test PCM brake switch input signal
Using a scope or multimeter, verify the PCM is receiving correct voltage changes (typically 0V when brakes are off, 5V when depressed). If signal is stuck high, trace the circuit for shorts to power.
- 4
Check PCM and reprogram if needed
If wiring and switch test normal, the PCM may require reprogramming or replacement. Have a dealer or certified technician verify PCM function and reprogram if necessary.
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