What does it mean?
B1727 is a Body (airbags, seat belts, body electronics) fault code. It indicates: Seat Driver Rear Up Switch Circuit Short to Battery .
Symptoms
- The rear of the seat cushion rises on its own or will not rise at all
- Seat tilt angle can no longer be set, while slide and recline still work
- Rear height motor stalls at the top stop and the thermal protection cuts in
- Memory recall aborts because the tilt axis never reaches its target
- Code returns immediately after clearing
Likely causes
- Contaminated seat switch pack where liquid has bridged the rear-up contact to the supply
- Rear height rocker contact welded or held closed by dirt and wear
- Rear-up signal wire chafed under the seat and touching a powered wire or the seat frame edge of a cut loom
- Corroded under-seat connector after water has soaked the carpet
- Aftermarket accessory feed spliced into the seat harness back-feeding the input
- Seat or memory module output stage failure
How to fix it
- Read codes and watch the rear-up switch input live while nobody touches the switch
- Move the seat through its full travel while wiggling the loom and watch for the input to go high
- Disconnect the switch pack; if the input normalises the switch is at fault
- With the switch unplugged, measure the signal wire for battery voltage to prove the short
- Inspect the loom at the rail, under the cushion frame and at the under-seat connector for chafe and corrosion
- Clean or renew the switch pack and repair the shorted wire with a sealed joint
- Replace the seat control module only after switch and harness have been cleared