What it means
Motor Control B Circuit High: the signal voltage is above the expected range. Often an open circuit or a short to supply voltage.
How it works
The ABS module monitors the electrical signal for Motor Control B. C0537 sets when the channel B signal is above its expected range, which can result from a short to a power feed or an open circuit that leaves the signal high; this is a high-condition fault, not a low-condition fault.
Common causes
Most likely first.
- Wiring shorted to battery
- Connector pins corroded - high contact resistance
- Supply wire pinched against B+ source
Symptoms
- ABS warning light on
- Traction or stability control warning light on
- ABS functions may be limited
How to diagnose it
- Use an ABS-capable scan tool to record freeze-frame data and check related Motor Control B codes.
- Inspect the channel B harness and connector for pinched wiring touching a power source, corrosion, or loose terminals.
- Compare Motor Control B live data with the manufacturer's expected range and determine whether the high reading is constant or intermittent.
- Use the wiring diagram to check the channel B circuit for a short to voltage and inspect terminal contact using the manufacturer's procedure.
- If the wiring checks out, test the associated motor or actuator and ABS module input as specified by the manufacturer.
Common fixes
- Repair a Motor Control B wire shorted to a power feed.
- Clean, secure, or replace corroded or damaged channel B terminals.
- Repair pinched or chafed wiring and restore proper insulation and routing.
- Replace a failed motor or actuator, or repair the ABS module, only if testing identifies it as faulty.
Can I keep driving?
The ABS module may limit ABS, traction control, or stability control while this fault is present. Normal braking may remain, but drive cautiously and allow extra stopping distance until repaired.
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.