What does it mean?
B1525 is a Body (airbags, seat belts, body electronics) fault code. It indicates: Seat belt switch (LH) circuit (ground side) shorted (for Normal/Open terminal) .
Symptoms
- Airbag warning lamp on
- Left side belt reminder always shows the belt as fastened, so no chime is heard
- Belt state in scan data does not change when the buckle is used
- Code returns immediately after clearing, because the short is permanent
- Belt pretensioner logic for that side disabled
Likely causes
- Belt switch cable rubbed through against the seat frame or a rail where it moves with the seat
- Harness trapped under the seat mounting bolt or crushed by a seat that was refitted carelessly
- Terminal backed out of the under-seat connector and resting against the seat structure
- Corrosion in the connector after a wet carpet, a leaking seal or a spilled drink
- Damaged section of loom left behind by earlier interior or trim work
- Internal short between the normally open contact and the switch body
How to fix it
- Confirm the fault by watching the left belt switch state in live data while latching and releasing the belt
- Unplug the buckle and measure the harness side to ground with the connector separated
- Trace the cable along the rails, looking for a worn or flattened section against the frame
- Remove floor mats and any items stored under the seat that could press the loom onto metal
- Inspect the connector for terminals touching the seat structure and for corrosion from moisture
- Repair the shorted section with correct terminals and route it clear of moving parts
- Replace the belt buckle assembly only if the short is proven inside the switch, then clear and retest