What does it mean?
B1622 is a Body (airbags, seat belts, body electronics) fault code. It indicates: ECU Software Error .
Symptoms
- Rear wiper runs continuously and only stops when the ignition is switched off
- Motor hunts and hums as it repeatedly tries to park
- Rear wiper starts on its own as soon as the ignition is turned on
- Motor overheats or the wiper linkage is damaged by constant operation
- On the software fault variant, the module behaves inconsistently and several body codes appear together after a battery or programming event
Likely causes
- Park position wire chafed against the tailgate sheet metal, pulling the input to ground
- Wiper motor park contacts stuck closed or full of water
- Broken wire in the tailgate hinge conduit touching body metal
- Corroded connector at the rear wiper motor
- Damage after rear glass, trim or spoiler work
- Module input pulled low internally
- On applications where this code reports a software fault, a corrupted or incompatible calibration, an interrupted programming session, or a configuration mismatch after a module change
How to fix it
- Unplug the rear wiper motor and see whether the code stops resetting, which separates the motor from the wiring in one step
- With the motor unplugged, ohm the limit wire to ground; a near-zero reading means the harness is shorted
- Inspect the loom inside the tailgate hinge conduit, which flexes every time the tailgate is used and is the usual failure point
- Check inside the motor for water and corroded park contacts, and inspect the housing seal
- Repair the harness or replace the motor according to what the measurements show
- On the software fault variant, confirm the latest calibration for the vehicle and make sure battery voltage is stable and supported during programming
- Reprogram the module following the manufacturer procedure and only replace it if it still fails afterwards