Buick Repair Questions? Ask a Mechanic for Answers ASAP
To clarify, you already replaced the trunk latch and the light is still on?
Ok. Do you have a scan tool that will monitor the trunk ajar signal?
Do you have a multi-meter to do some electrical testing?
So the red with black stripe wire at the trunk latch should have ground when the trunk is open and then be open when the trunk is shut. So if you unplug the latch connector it should turn the indicator light off. If it doesn't then it means the red with black wire is shorted to ground somewhere between the latch and the rear integration module. Trace the wire as far as you can go and check for signs of rubbing though where the wire is contacting ground.
Next, unplug the connector for the rear integration module and check for ground at the B3 pin in the trunk open and trunk closed positions.
It should be right behind the rear seat on the driver's side.