What does it mean?
B1554 is a Body (airbags, seat belts, body electronics) fault code. It indicates: Turn Signal Multifunction Switch Error .
Symptoms
- Trunk lid pops open on its own, sometimes while driving
- Trunk release button does nothing, or works only when the body is warm and dry
- Trunk fuse blows repeatedly
- Trunk lamp stays on and the battery drains over a few days
- Cluster shows the trunk as open with the lid closed and latched
- On the stalk variant, turn signals, high beam or flash-to-pass work intermittently
Likely causes
- Wire chafed where the loom crosses from the body into the decklid, the point that flexes every time the trunk is opened
- Water entering the trunk latch and corroding the release actuator terminals
- Release actuator shorted internally after long exposure to moisture
- Dash-mounted or remote release switch stuck closed or contaminated
- Corroded ground point in the trunk area giving a false low reading
- Damage from cargo, a towbar wiring installation or an aftermarket alarm tapped into the release circuit
- Body module output driver damaged by the short
- On applications where this code refers to the combination stalk, an internal fault in the turn signal multifunction switch
How to fix it
- Disconnect the trunk latch actuator and see whether the code stops setting, which immediately separates the actuator from the harness
- With the actuator unplugged, ohm the release circuit to ground; a near-zero reading confirms a short in the wiring
- Inspect the section of loom that crosses into the decklid and flex it while measuring, since broken strands often only touch metal when the lid moves
- Open the latch and check for water, rust and corroded contacts, then check the trunk seal and drain path
- Measure the release switch on the dash and the remote input for a stuck closed contact
- Repair the harness and re-route it inside its protective conduit; replace the latch actuator if it measures shorted
- On the stalk variant, test the other functions on the same multifunction switch to decide between the switch and its wiring