What does it mean?
B1847 is a Body (airbags, seat belts, body electronics) fault code. It indicates: Power Seat Rear Up-Down Switch Circuit Malfunction .
Symptoms
- Rear of the seat cushion will not raise or lower
- Seat sits nose-up or nose-down and cannot be levelled
- Rear height moves in one direction only
- Memory recall ends with the wrong cushion height
- Seat height adjusts on its own without input
Likely causes
- Rear height switch contacts worn or contaminated
- Open or short circuit in the rear up-down signal wire
- Harness damaged under the seat where it flexes as the cushion rises
- Dirt and liquid inside the seat switch pack
- Loose or corroded connector at the seat module
- Rear lift motor jammed or drawing excessive current
- Module input failure
How to fix it
- Watch the rear up-down switch status in live data while pressing it both ways
- Unplug the switch pack and measure the contact resistance in each position
- Inspect the harness under the seat with the cushion fully raised and lowered
- Back-probe the module input and confirm the expected voltage change
- Measure the rear lift motor current draw during operation
- Replace the switch pack when the contacts are open or intermittent
- Replace the seat module last and relearn the seat memory positions