1986 C4 Corvette. Been sitting for years. Bought it as a project car with my son. Got it running, took for a drive at night and the interior was pitch black. Couldn't see what gear it was in, couldn't see the heater controls, couldn't see the gear shift light, couldn't see the switches to adjust instrument cluster.

Decided to try replacing a few bulbs. Checked voltage, nothing. No prob I thought...just replace the fuse...knew they were oxidized in the fuse panel after replacing a different one. Took every fuse out associated with anything interior lights. None were blown, all were oxidized. Anxiously turned headlights on. Nothing. All lights above still not working.

Spent hours researching on this forum. Nothing pointed to the potential problem. Went out tonight, tried debugging for 45 minutes. Nothing.

Finally did another search on the forum and found a thread that indicated parking lights were on the same circuit as said interior lights. Prayed, pulled the "Tail" fuse only to discover it wasn't blown...but was oxidized. Sanded the terminals clean, sprayed electronic cleaner in the slot of the fuse box, prayed again but was certain it wouldn't help.....

Pulled the light switch and wahoo! All the above mentioned lights came on!!! HVAC control lights work, gear shift illumination lights work. Parking lights work. Instrument cluster control lights work. I have night lights! What a relief. I feared a major electrical debug but it was a fuse that wasn't blown but oxidized!!

Who would guess the tail light circuit was also the interior night light circuit?

Posting in hopes someone else who has the issue will easily find my post to save them the hours of grief I had...

Note: I even began studying the schematics and the manual. Nothing pointed to tail lights being on the same circuit.

What a relief. Now we're going to replace all the bulbs with Amber LEDs to brighten everything up including the instrument cluster...with $1 LEDs from Amazon instead of $40 for the LED "KIT"

 

Makes sense...but I would have expected the manual to more explicitly call this out 🙂

 

You’d think the TAIL FUSE feeding everything after the Light Switch would be a clue:

 

Love this diagram. I have a Haynes manual. It's almost worthless. What manual did you pull this from? Thx