Odd running light issue

[comanche32]

So my 1990 comanche has a passenger side running light that won't work. All turn signals brake lights work. It's not the bulbs or sockets. What would cause the running light to not work on one side

[Eagle]

What do you mean by "running lights"? The parking lights, or the side marker lights?

 

[jpnjake]

5 hours ago, comanche32 said:

So my 1990 comanche has a passenger side running light that won't work. All turn signals brake lights work. It's not the bulbs or sockets. What would cause the running light to not work on one side

I know on the late model xj’s they split the harness and had them fused individually, but I’m not sure thsy did that with the Mj’s , other than that. I’d check the wiring diagrams and find the body ground for the lights and clean it up. Bad grounds do funky things 

[comanche32]

By running lights I mean the tail lights on the passenger side. It's a double filament bulb. The brake and turn signal function fine. But the tail light doesn't. I've tried 3 different bulbs the only thing that doesn't work is the passenger side tail light 

[cruiser54]

Does someone have a trailer harness hacked into the back of your truck?

 

Have you used a test light or meter to check for power and grounds? 

[comanche32]

Yes there is a trailer harness spliced in. It's just weird that the brake light and turn signal part of the light function. But the running light doesn't.

[Pete M]

gotta get into the harness and see where the wire has broken/corroded.   

[comanche32]

Which wire controls the passenger tail lights do you know