What does it mean?
B1991 is a Body (airbags, seat belts, body electronics) fault code. It indicates: Right Power Sliding Door Sensor Supply Circuit Low .
Symptoms
- Right power sliding door disabled and only usable manually
- Several door sensor codes stored together, all sharing the same reference
- Door stops partway or refuses to start moving
- Repeated chime when the door button or handle is used
- Fault comes and goes with weather, or after the door has been used repeatedly
Likely causes
- Sensor supply wire shorted to ground inside the sliding door harness or the flexible track loom
- One door sensor failed internally and loading the shared reference
- Water in a sensor or module connector, common on the lower door and sill area
- Harness crushed at the sliding track or by the door roller mechanism
- Corroded terminals producing enough voltage drop to fail the reference check
- Overloaded regulator inside the sliding door control module
- Poor power feed or ground for the module itself
How to fix it
- Measure the sensor reference voltage at the sliding door module with the ignition on and compare it with the specification
- Disconnect the door sensors one by one and watch for the reference to recover, which identifies a shorted sensor
- With everything unplugged, check the supply wire for a low resistance to ground and split the circuit to localise it
- Examine the flexible harness that follows the door, opening the loom where it bends most
- Check the module power and ground with voltage drop tests before blaming its regulator
- Dry and clean all connectors in the circuit and repair corroded pins
- Repair the short or replace the failed sensor, then clear the codes and run several full door cycles to confirm the reference stays steady