Headlight and electrical issues
Truck is an ’87 F350 IDI. Installed new headlights and still having major lighting issues.
Symptoms:
- Both headlights not functioning correctly
- Weird voltage readings at the headlight connectors
- Passenger outer marker/running light does NOT work normally, but DOES flash when the turn signal is activated
- With a test light/meter I’m getting strange partial voltage readings (around 6V in some spots)
- Headlights seem to backfeed through other lighting circuits
- Replaced bulbs already
- Tried running a direct ground from headlight ground to battery negative with no change
- Headlight switch visually looks good internally
- Fuse slot that should’ve had a 15A fuse had a 30A in it when I bought the truck
Truck was apparently involved in a minor fire years ago near the driver front quarter area, but interior/dash wiring appears untouched and not melted.
At this point I’m trying to narrow down whether this sounds more like:
- bad front lighting ground
- dimmer switch
- bulkhead connector issue
- headlight switch issue
- radiator support ground
- or common OBS Ford wiring failure
Anyone dealt with similar symptoms where the parking/marker light only works during turn signal operation and the headlights show weird voltage/backfeeding issues?