Cab lights not working

[Jsmith]

I have a 1987 GMC V3500. The cab lights and tailgate marker lights are not working. I have checked the cab light bulbs. They appear to be good. Don't know what could be causing it? Any ideas?

Also, none of my gauge lights work in the interior. Think that might just be the bulbs. Don't think the issue is related.

Thanks!

 

[GregL]

Have you checked your fuses?

 

[Tank6x2]

Check output voltage at plug with a voltage meter, compare to your battery available voltage. Reads zero on all, ground or power fault possibly corroded wire, reads source battery voltage then bulb.

 

[HotRodPC]

I have a 1987 GMC V3500. The cab lights and tailgate marker lights are not working. I have checked the cab light bulbs. They appear to be good. Don't know what could be causing it? Any ideas?

Also, none of my gauge lights work in the interior. Think that might just be the bulbs. Don't think the issue is related.

Thanks!

The issue most likley IS related. Tail and marker lights are on the same circuit as your dash lights, so when the fuse blows, you lose all your tail, marker and dash lights.

How I know? I was once towing a trailer from out of town. My damn dash lights went out about 10 miles from my destination. I got pulled over and was like WTF did I do wrong? I was pulled over for no taillights and no trailer lights. I replaced the fuse and it happened again like 5 miles later. Come to find out, my trailer tail light was grounding out and blowing my Tail/Tag Marker light fuse and taking my dash lights out with it.

 

[Jsmith]

I have checked the fuses and the actual tail lights work. I'm talking about the 5 red markers are on the tailgate. I haven't checked the voltage though. I will do that next. Thanks.

 

[HotRodPC]

I have checked the fuses and the actual tail lights work. I'm talking about the 5 red markers are on the tailgate. I haven't checked the voltage though. I will do that next. Thanks.

Just the tailgate marker lights? Not the roof marker lights, side markers or tail lights? If so, I'd suspect the tailgate wiring then and yes, then the dash lights is likely a separate problem. Could even be in the headlight switch itself.

 

[Jsmith]

Cab lights, tailgate markers and dash lights don't. The front fender markers do work though. Didn't even think about the headlight switch itself.