What does it mean?
B1504 is a Body (airbags, seat belts, body electronics) fault code. It indicates: Left Steering Wheel Control Switch Circuit .
Symptoms
- Audio, phone or cruise buttons on the left side of the wheel do not work
- Pressing one button triggers a different function
- Phantom button presses, such as volume changing on its own
- Buttons work intermittently as the wheel is turned, which points to the clockspring
- Airbag or horn faults appearing at the same time if the clockspring is damaged
Likely causes
- Worn or contaminated contacts inside the left switch pack, often after a drink spill onto the wheel
- Failed resistor ladder in the switch, so button values fall outside the recognised windows
- Worn or broken clockspring track carrying the switch signal through the steering column
- Open, shorted or high resistance wire between the clockspring and the receiving module
- Loose or corroded connector behind the wheel airbag or at the column
- Fault in the module that reads the switches, such as the radio or body control module
How to fix it
- Watch the switch status or measured resistance in live data while pressing each button in turn
- Note whether only the left pack is affected; if the right pack works normally the wiring back to the module is probably good
- Check whether the fault changes with steering wheel position, which indicates a worn clockspring
- Unplug the switch pack and measure its resistance at the connector for each button against specification
- Inspect the connector behind the wheel for corrosion, bent pins and a loose lock
- Replace the switch pack if its resistance values are wrong, or the clockspring if the signal drops with wheel rotation
- Replace and configure the receiving module only after the switch, clockspring and wiring test good