What does it mean?
C1287 is a Chassis (ABS, traction control, steering) fault code. It indicates: Booster Control Circuit Malfunction . This is a standardised OBD-II code. The technical definition is the same regardless of the make or model of vehicle, although specific causes and symptoms can vary between vehicles.
Symptoms
- Brake assist inconsistent, with the pedal feeling harder or softer than usual from stop to stop
- Red brake warning lamp with ABS and stability lamps
- System drops into a fail-safe mode with reduced assist
- Booster does not respond to a commanded test with the scan tool
- ABS and stability control unavailable
Likely causes
- Open or short circuit in the control line between the module and the brake booster actuator
- Corroded or wet connector at the booster or at the module
- Harness chafed where it passes the bulkhead or a moving bracket near the pedal box
- Shorted booster solenoid or valve loading the control circuit
- Poor module ground so the commanded signal level is wrong
- Low system voltage making the module unable to drive the booster correctly
- Failed control driver inside the brake control module
How to fix it
- Command the booster with the scan tool bi-directional function and watch for a response
- Back probe the control circuit and check that the signal changes when the command is given
- Unplug the booster and check the control circuit for short to ground and short to battery voltage
- Test continuity from the booster connector to the module pin
- Measure the booster supply voltage and ground quality under load
- Inspect and repair the harness and connectors, drying and sealing where water is found
- Replace the booster assembly, and consider the control module only after the circuit tests good