Trip Odometer Does Not Reset
WARNING: This page is about a different car, the 1997 Buick Regal and 1997 Buick Century. However, it is still accessible from the selected car via links, so may be relevant.
Turn ignition on. Set odometer to TRIP. Using fused 5-amp jumper wire momentarily backprobe between accessory switch panel connector terminal "H" (Light Green wire) and ground. If trip odometer display resets to zero, check wiring for poor connection. If connections are okay, replace trip reset switch. If odometer does not reset to zero, check Light Green wire for open circuit or high resistance. If wiring is okay, replace instrument cluster.