seat belt light 86 coupe

That's a pretty simple circuit. Power is fed to the chime module, then sent to the light at key switch ON. When the driver's seat belt is buckled, a switch in the buckle itself opens, breaking the circuit and turning off the light. Only the driver's buckle has the switch.

Try driving the car a short distance without buckling the belt. If you get a slow chime for the first few seconds after putting it in Drive, the circuit is okay and the seat belt switch is probably bad. Try spraying some contact cleaner in there first. If that doesn't work, I'd just pull the bulb. If there's no chime, it's likely the chime module, and I'd still pull the bulb.

Ignore my first post. I should have looked at the schematic first. The circuit is actually even simpler than that.

The light is just a reminder that gets power from the chime module and stays on for 5-8 seconds with the key in RUN or START. The light comes on even if the belt is buckled. If the driver's belt is unbuckled, a slow chime will also sound. But that's the extent of it. Under normal operation you can unbuckle your seatbelt while driving and no light or chime appears.

Best guess would be the chime module is faulty. Get one from a junkyard (85-88 C-body) if you want the system to work again, or simply pull the reminder bulb.

Noahsdad thanks for your help

Tallpat