Drivers who encounter a P0724 “Brake Switch B Circuit High” code usually notice that the brake‑light illumination does not behave normally. The lamp may remain lit after the pedal is released, and the dashboard often displays an ABS or stability‑control warning. Cruise‑control, which requires a valid brake‑switch signal to disengage, may refuse to activate. In some cases the brake pedal feels softer because the vehicle’s electronic brake‑assist system is being disabled. These symptoms appear suddenly and persist until the fault is cleared, prompting the check‑engine light or a dedicated brake‑system warning to illuminate.
The brake‑switch B is a two‑position sensor that should output a ground (0 V) when the pedal is released and a 5 V signal when pressed. Internal contact wear or a shorted circuit can cause the output to remain at a voltage above the module’s upper limit, triggering the “circuit high” condition.
A damaged wire, pinched harness, or corroded connector can introduce an unintended voltage source to the switch’s signal line. Water intrusion, especially in regions with road salt, often creates a high‑impedance path that raises the voltage seen by the control module.
The body control module (BCM) or ABS control module processes the brake‑switch signal. A failed input driver, burnt trace, or internal component degradation can misinterpret a normal switch voltage as excessively high, generating the P0724 code even when the switch itself is functional.
Occasionally, a module’s firmware may contain a calibration error that misclassifies normal voltage fluctuations as a high‑circuit condition. An outdated calibration can also prevent the module from recognizing a newly installed switch, leading to persistent fault storage.
Connect a professional OBD‑II scanner, read the stored codes, and confirm that P0724 is present without other conflicting brake‑system codes.
Access the brake‑switch B sensor voltage in real‑time mode. A normal reading is 0 V (pedal released) and ~5 V (pedal pressed). Values consistently above 5 V indicate a high‑circuit condition.
Using a multimeter, measure voltage directly at the switch connector with the pedal both released and pressed. Compare to the live‑data values. Discrepancies suggest wiring issues.
Visually examine the harness for chafing, pinches, or corrosion. Use a continuity tester to verify that the signal wire is not shorted to power or ground. Repair any damaged sections with automotive‑grade heat‑shrink tubing and proper crimp connectors.
Disconnect the switch and apply 5 V from a bench power supply while measuring the output. A stable 5 V indicates a functional switch; a voltage that climbs above 5 V confirms a defective sensor.
If the switch and wiring test within specifications, the fault likely resides in the control module. Perform a module communication test using a dealer‑level scan tool to verify that the BCM/ABS module responds correctly to other inputs. A failure here points to internal module damage.
Many high‑circuit faults are resolved by flashing the latest software version. Follow the manufacturer’s reprogramming procedure, which typically requires a laptop with the appropriate OEM software and a calibrated interface cable. Reprogramming costs range from $150 to $300, including labor.
When the module’s input driver is irreparably damaged, replacement is the reliable solution. Replacement units vary by production date and software version; the correct module is matched to the vehicle’s VIN before programming. Expect parts costs of $600‑$900 plus $200‑$300 labor.
After reprogramming or replacement, clear all codes, then drive the vehicle through a brake‑pedal cycle to ensure the P0724 code does not return. Re‑scan to confirm a clean diagnostic session.
Service Recommendation: Most issues related to this fault are diagnosed and corrected through inspection, wiring repair, and calibration rather than module replacement. For modules not typically replaced through aftermarket suppliers, diagnosis and repair should be performed by a certified automotive technician with access to factory service information and tooling.