What it means
Cruise Control/Brake Switch B Circuit High: the signal voltage is above the expected range. This affects cruise-control operation.
At a glance
- Usually lights the check-engine light
How it works
Brake-switch circuit A provides the brake-pedal state used by the control module to cancel cruise and, on some vehicles, operate the shift interlock. This high-circuit code means the A signal is above its expected range, often because the circuit is open or the switch or connector is not passing the signal correctly.
Common causes
Most likely first.
- Brake switch defective
- Wiring open
- Connector pins corroded - high contact resistance
Symptoms
- Check-engine light may come on
- Cruise control may not engage or may disengage unexpectedly
- Brake lights may stay on or fail to illuminate
- Shift interlock may not release on vehicles that use this signal
How to diagnose it
- With the vehicle parked, check whether the brake lights illuminate and turn off correctly as the pedal is pressed and released.
- Monitor brake-switch A on a scan tool while operating the pedal; note whether its reported state remains high or fails to follow pedal movement.
- Inspect the brake switch at the pedal for damage, looseness, or incorrect adjustment, and check its connector for corrosion or loose terminals.
- Trace the A signal wire for an open circuit, damaged insulation, or poor connection, using the vehicle wiring diagram.
- Test switch continuity and the A circuit against the manufacturer's specification to locate the open or failed connection.
Common fixes
- Correct a misadjusted brake switch if it is not being actuated by the pedal.
- Reconnect or clean a loose or corroded connector.
- Repair an open or damaged wire in the A signal circuit.
- Replace a brake switch that fails its circuit test.
- Repair the related module connection if the switch and harness pass testing.
Can I keep driving?
Check the brake lights before driving; if they fail or stay on, do not drive until the fault is repaired. Avoid cruise control because the brake signal may not cancel it correctly, and a shift interlock problem may also occur on some vehicles.
A code shows where the control module detected a fault, not always which part failed. Check the causes in order and confirm with a test before replacing parts. Have several codes? Check them together
This is a generic code: it means the same on every make. The car’s maker may add more detail in its own service information.