1990 k5 Rear Tail light Wiring

[Justin Fleming]

Guys need a little help here. My drivers side rear running light is working perfectly bright etc. when I turn that blinker on (same bulb), it blinks so dim you cant hardly see it, but if you get real close you did see it going on and off with the flasher sequence and if you push the brake (same bulb) it is so dim you cant hardly see it. So I would lean towards this being a ground? But if it were a ground I would think the running lights would not be so good? The picture shows the wiring and socket, is it assumed that the black wire is the ground ? Any trouble shooting tips or ideas?

I moved the passenger bulb over for testing and had the same results so I know it is not the bulb

 

[Wes Harden]

the yellow is brake and turn. The brown is tail. Black will be ground. Give the trailer wiring a good once over before tearing into anything else.

 

[Bent77]

The dim bulb routine is telling me ground

 

[Justin Fleming]

I had a T-wiring harness in the mix for the trailer wiring, I unplugged that completely because with that plugged in I was not getting the running light. So right now there is no trailer wiring in the mix and the two factory connectors are plugged together.

 

[Wes Harden]

if there is no other trailer wiring patches, then go after that socket ground

 

[Justin Fleming]

would the fact that the running light is working perfect..... is that not the same ground in the socket?

 

[Bent77]

It might terminate in the same spot, but the socket could be bad

 

[Justin Fleming]

Does anyone have the wiring schematic for the tail lights system?

 

[dyeager535]

Does anyone have the wiring schematic for the tail lights system?

Believe the wiring diagrams are here: https://ck5.com/forums/ck5/technical-service-manuals-view-only.109/ Generally I think all years are the same for the tail lights, but best to use correct year diagram just in case.

 

[Justin Fleming]

So guys you have to love the old corroding wires in our K5's. So I narrowed the issue down to this section of wire, then I opened it up....had about 5hrs of trouble shooting into it, if you stay persistent with your trouble shooting you will find it!! The odd think was the outer jacket looked perfect with no bulging signs or anything....