What does it mean?
C1225 is a Chassis (ABS, traction control, steering) fault code. It indicates: SM Solenoid Circuit .
Symptoms
- Brake warning lamp lit constantly, or dead and failing its key-on bulb check
- Lamp stays on with the parking brake fully released and the fluid level correct
- ABS and stability control may be switched off as a precaution
- Warning behaves the same whether the ABS module is plugged in or not
- Vehicle fails inspection because a brake system warning is permanently displayed
Likely causes
- Lamp control wire chafed against a live circuit behind the dashboard or along the bulkhead
- Moisture or corrosion in the instrument cluster connector bridging the lamp pin to a live pin
- Aftermarket accessory, alarm or trailer module spliced into the brake warning circuit
- Damaged output driver inside the ABS module holding the circuit high
- Instrument cluster internal fault feeding the lamp line
- Incorrect repair after a previous cluster or harness replacement
How to fix it
- Rule out a genuine brake warning first by checking fluid level, pad wear and the parking brake switch
- Disconnect the ABS module connector and measure voltage on the lamp control wire with the key on; voltage present confirms the short to battery
- Inspect the harness behind the dashboard and along the bulkhead for rub-through against live cables
- Check the cluster connector for corrosion, water tracks and pushed back terminals
- Disconnect any added accessory or trailer wiring from the circuit and retest
- Repair and re-route the damaged section, then confirm normal lamp behaviour through a key-on cycle
- Replace the cluster or the module output only after the harness measures clean