Road Runner Nest

My GTX passenger tail light is acting weird. The running lights work, but no turn or brake. Replaced all the bulbs no change. I thought maybe ground was bad, but then the running lights work so it cant be that. Maybe socket? Has anyone had similar issues? Any help would be appreciated.

Go with your first hunch. Check the ground.

Does not seem to be a ground issue. I thought maybe the sockets were bad, but both going out at same time seemed weird. I started to look at harness, but quickly became confused with brake and turn wires using one lead. Not sure how that works. Any clues?

There is a ground lead screwed to the body inside the trunk. Next to the side marker if I recall correctly Make sure it is in good contact.

What you are describing is what happens when you don't have a good ground. The running lights ground themselves by back feeding through the turn signal circuit.

Remember the light sockets are 40 years old,and the springs and so forth inside the sockets can corrode,causing problems.Also after years of vibration the led things where the bulb makes contact can be wore out.

I had the same identical problem with my 70 road runner. You have to replace the turn signal collar switch behind the steering wheel in the column ( the wiring harness runs down inside the column and connects to another connector underneath dash. the brake lights and turn signals and hazzards all run off it. U may still be able to find a replacement part. its the same replacement part for 80's dodge ram trucks with column. u will have to shave the hazarrd button so that it will fit when depressed.

Thanks for all the help. Ground in trunk was in good shape. I guess I have to either pull the rear bumper and take a look at housing closely or pull steering wheel to check turn signal ring. The GTX needs a new rear bumper, so maybe I'll just pull it off and check lamp housing. I will let everyone know what I find out. Maybe upgrade to the LED bulbs while I'm at it.

Before you pull the entire bumper, there are a couple of connectors which are located approximately behind the license plate opening. It is possible that your plate mechanism may have caused one of these connectors to come loose while putting in fuel.

I did do a a check of all the rear wiring starting in the trunk. It all looks good.Got power going all the way to trunk, so I guess that means the housing is probably the issue. Thought I found a new bumper yesterday to replace mine, turns out a 72 is not the same as a 71. Thanks for everyones help.