So, as the post says, I'm having trouble with my tail lights.

So, what happens is that my brake lights will not function when my headlights are on, nor will my turn signals. And this is a huge problem, seeing as I'm a 3rd shift worker.

I also don't have the tools to check for shorted wires.

Another thing is that sometimes the tail lights and side marker lights stay on after I turn off the light switch. Pushing the brake pedal turns them off.

Another thing is that when the turn signals are activated, they both flash as if they are in hazard light mode.

Do I need to go ahead and buy a new rear wiring harness? Or is this a simple fix?

Any help or advice is much appreciated.

Thanks!

Is the wiring harness butchered up?

Ideally, you diagnose a problem and determine what is wrong before you start throwing parts at something to repair your car.

That said, it Could be that the problem is mainly with your headlight switch itself. It might be the source of most or all of your problems.

The headlight switch doesn't just control your headlights, instead most all lighting control passes through the switch. On vintage cars, lots of current passes through that switch plus they are subject to corrosion issues over time.

Headlight switches aren't all that expensive or difficult to replace, but in the end, that may or may not be the problem. If it were mine, I would visually inspect the wiring and if nothing else was obvious, replace the headlight switch if it is Original or really old just on general principle, but that has to be your decision, not mine.

Thanks for the reply! I did a visual inspection earlier in the day, and couldn't find anything out of place. Fuses appeared fine as well.

The gauges in my Valiant were replaced with rally gauges from a Barracuda of the same year (I think).

Will try replacing the switch. Thanks again.

Bad ground! Likely at the rear harness possibly the front. Look for a wire that screwed to the trunk floor and core support. Those are the grounds, clean and tighten those connections and report back...

Simple check. Make sure the bulbs are good and not shorted internally.

Hi Rogue_leader007, long time no see.

have you upgraded to the newer voltage regulater?

might have a look at the blinker switch as it wears out and will sag enough to kill a brake light or light it up.

the TS & brake light all go thru the TS switch in the colum.

revs light switch is down on the colum by floor and is adjsuable and works off a roll pin in the colum.

I added ground wires to all the rear light housings grounding to the trunk frame rail.

running the screws for the dash cluster helps light up dash lights as thats the ground for the cluster. run them in out a few time just so you know they are clean.

might have a look at the brake light switch to see if it is mis adjusted at the pedal.

I have to say the newer solid state upgrade VR did the most for my old 68 dart when it came to grounds/juice/lights working.

good luck