What does it mean?
B1815 is a Body (airbags, seat belts, body electronics) fault code. It indicates: Driver Seat Recline Forward Switch Circuit Malfunction .
Symptoms
- Seat back will not tilt forward, while other seat movements still work
- Recline moves in one direction only
- Seat back moves on its own without the switch being touched
- Memory recall stops partway through because one axis will not move
- No motor sound at all when the forward direction is selected
Likely causes
- Worn or contaminated contacts inside the seat switch pack
- Open or short in the recline forward signal wire under the seat
- Under-seat harness pinched or stretched by the seat rails at the ends of travel
- Spilled liquid running down the seat side trim into the switch
- Under-seat connector partly unplugged after cleaning or child seat installation
- Poor power or ground supply to the seat control module
- Seat module input stage failure
How to fix it
- Operate the switch while watching its status in live data
- Unplug the switch pack and measure the contact resistance in rest and pressed positions
- Move the seat fully forward and back and inspect the harness for pinching at the rails
- Back-probe the module input pin and look for the expected voltage change
- Check the seat module fuse, supply voltage and ground with a voltage drop test
- Replace the seat switch pack if the contacts are open or erratic
- Replace the seat module last and recalibrate the memory positions