What does it mean?
B1829 is a Body (airbags, seat belts, body electronics) fault code. It indicates: A/T P Signal and VSS Signal Mismatch .
Symptoms
- Key or shifter interlock misbehaves, the shifter will not leave Park or the key will not come out
- Speedometer reads erratically or drops to zero while moving
- Gear position display on the cluster is wrong or blank
- Doors auto-lock or unlock at the wrong moment
- Steering column lock or push-button start refuses to operate on some vehicles
Likely causes
- Transmission range switch worn, misadjusted or contaminated
- Shift cable out of adjustment so the range switch does not match the real gear
- Vehicle speed signal missing, noisy or dropping out at low speed
- Wheel speed or transmission output speed sensor fault feeding bad data to the network
- Broken wiring or corroded connector on the Park signal line
- Network message from the transmission or brake control module missing or arriving late
- Module configuration mismatch after a control unit replacement
How to fix it
- Compare gear position and vehicle speed in live data while driving slowly in a safe area
- Cycle the shifter through every position and confirm each one is reported correctly
- Check the shift cable adjustment and the alignment marks on the range switch
- Look for wheel speed or output speed sensor codes stored in other modules
- Inspect the range switch connector and wiring for corrosion and chafing
- Adjust or replace the range switch, or repair the speed signal circuit
- Recheck for network communication faults and reconfigure the module if it was recently replaced