What does it mean?
C1253 is a Chassis (ABS, traction control, steering) fault code. It indicates: Brake Booster Pump Motor Relay Coil Circuit Failure . 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
- Booster pump does not run, so the brake pedal becomes hard and needs high effort
- Brake and ABS warning lamps on, usually with a system warning message
- No relay click when the ignition is switched on
- Stability control and other brake assistance functions disabled
- Stopping distances noticeably longer, making the vehicle unsafe until repaired
Likely causes
- Open winding in the relay coil
- Broken control wire between the module and the relay coil terminal
- Coil control wire shorted to ground or to battery, which the module also reports as a coil circuit fault
- Missing ignition supply to the coil because of a blown fuse or an open feed
- Corroded or spread terminal in the relay socket on the coil pins
- Water in the fuse or relay box reaching the coil circuit
- Low side driver in the module failed, so the coil is never switched to ground
How to fix it
- Depressurise the system as specified before working near the hydraulic unit
- Remove the relay and measure the coil resistance, comparing it with the specification
- With the key on, check that the coil supply terminal in the socket has voltage
- Command the pump with the scan tool and check whether the module pulls the coil control terminal to ground
- Check the control wire for an open circuit and for shorts to ground and to battery
- Inspect the relay box for water ingress and clean or dry the socket and terminals
- Replace the relay or repair the wiring, and consider the module driver only once the coil circuit is proven good