What does it mean?
B1587 is a Body (airbags, seat belts, body electronics) fault code. It indicates: Tailgate Chime Short to Ground .
Symptoms
- The headlamp-off delay cannot be extended and always defaults to the shortest setting
- The delay jumps between settings instead of stepping evenly
- Headlamps go out immediately after the key is removed, leaving no light to walk away by
- Headlamps stay on far longer than selected and drain the battery
- On the chime variant, the tailgate warning sounds continuously or never sounds at all
Likely causes
- Worn or dirty contacts inside the autolamp delay control, so the increase step is never registered
- Corroded or loose connector at the control head or at the module
- Broken wire between the delay control and the module behind the dash
- Liquid damage inside the control head
- Unstable reference voltage or a poor ground at the control
- Module input stage failure
- On applications where this code refers to the tailgate chime, a chime circuit shorted to ground, often through a wet tailgate switch
How to fix it
- Read the autolamp delay setting in live data while moving the control through each position and note which steps register
- Back-probe the increase input at the module to confirm the signal level changes with the control
- Bench-test the control for continuity in every detent rather than only at the ends of its travel
- Inspect the connector and the loom behind the dash for corrosion, spread terminals and chafe
- Confirm module supply and ground with a voltage drop test before condemning parts
- Replace the control head only after it fails a direct continuity test
- On the chime variant, unplug the tailgate switch and ohm its circuit to ground, checking the switch and its wiring for water damage