Cargo and Interior lights don't work on my 1987' F150 I just bought. I traced the wires and there are 2 that just end, not connected to anything. The other 2 run down under the dash I'm guessing for power. What do the other wires do and where should they connect? Maybe the button on door? I have tried to ground them and that doesn't seem to do it

 

First guess would be no power. (the bulbs aren't burned out right. (ya gotta ask. ) As I recall, the light switch turns on both interior and cargo lights. Door switch only turns interior light on.

What do the other wires do and where should they connect?

Ummm, map light maybe? Mine has a map light built into the interior light panel. Can't think of anything else.

 

Did you ever get this figured out. Having the same problem with my cargo light. The bulb has good filaments but does not light.

 

Don't know if he ever figured it our or not but here's a thought. Have you checked the ground? If the interior light comes on the cargo light should work too. If it doesn't, (like you said) you can check the ground with a continuity meter or an alternate method is to check for power at the socket with a meter or test light. If you get power it's either a bad ground, a bad bulb or socket or maybe just a bad connection to the bulb. (Try wiggling the bulb and see what happens.) Hope this helps.

 

Or it could be weird like my truck, and the dome light no longer comes on with the cargo light, it used to... But it does when I open the door

 

Never did figure it out guys any of you?

 

I guess not. You're gonna have to get a wiring diagram for your truck (get a motor manual with one in it, $25 bucks.) and figure it out. Wish I could be more help. Good luck.

 

Finally got mine working, was a frayed exposed wire about an inch in.... Was rubbing/shorting.