Brake Light Stumper

[70 Challenger Lover]

Okay first off, I really don't like electrical stuff and I know only enough to make everything worse.

Last minutes fixes and checks getting the RT ready to put up for sale. All lighting worked perfectly the other day but now I notice the brake lights are not operational. Gotta be something simple but I just can't trace it down.

The housings are nice and properly grounded. The bulbs are new. The rear wiring harness is new. Everything worked perfect the other day and I've done nothing to the car recently to possibly change that other than drive it.

Both left and right turn signals work perfectly at the back end and the filaments for those bulbs are the same as the brake lights but for some reason no signal is being sent back there when the brake pedal is depressed. If the turn signals work, this tells me the issue is under the dash.

I started at the fuse block and everything has power at both ends of the fuse. I checked for power at the switch on the brake pedal and that is also good. When I depress the pedal, I get power at the other end of that switch so I know that is functioning properly.

It has to be something simple. I know that somehow, when the brake pedal is depressed, power should be routed through the same bulb circuits that activate the rear turn signals but there is no separate wiring in the rear wiring harness for that so that must happen somehow in the main wiring harness under the dash.

What more can I trace down and check here? Did I mention I really don't like electrical stuff?

[Chryco Psycho]

Has to be in the turn signal switch , try pulling the turn signal arm towards you

[70 Challenger Lover]

Didn't think of that. I messed around with the turn signal arm and couldn't get anything. As soon as I turned the hazards on and off a couple times though, brake lights started working again.

I rebuilt the column a while back but I never put in a new turn signal switch because the old one seemed to work just fine. After getting everything back together a few months ago, I noticed the hazards did not work but I wasn't overly concerned since that was the only problem. So there must be something a little loose inside that switch causing this brake light issue.

Working now so I'll leave it be and see if it happens again. I'll let potential buyers know they may want a new turn signal switch at some point.

Thanks for the great advice!

[Chryco Psycho]

The repro switches often are not a whole better at times . the part# is TW7 from Rock Auto , made by Standard

[dodj]

I'm going to say there is a connector behind the drivers kick panel to check if it does not turn out to be the t-switch.

[JH27N0B]

I'm electrical challenged myself, but I've run into brake light problems on my Challengers in the past where the switch on the brake pedal just needed a little adjustment to make my brake lights function correctly.

[Slotts]

This is one that was sent in with the same brake light issue from a 70 B body. The B body cars push in to turn the hazard lights on and the E body pull out to turn the hazard lights on. That is why these pictures look backwards from the E body version.

The pictures tell the story of the rivets getting hot and melting into the plastic and no longer make contact. When resistance increases for ground between the light bucket(s) and the finish panel, rather from paint or corrosion, the hazard switch area takes the build up of heat. I am not finished with this part, but will be building up the melted in areas to be flush with the housing. Then I am going to Home Depot to their Mopar restoration section to get some copper tubular rivets to install. (I make my own) As long as the ground issue(s) are taken care of in the back of the car, the problem will be solved.

Jim

[70 Challenger Lover]

I'm going to say there is a connector behind the drivers kick panel to check if it does not turn out to be the t-switch.

I did actually examine that connector and there are only two wires that affect the brake light circuit. One wire is for the left turn signal and the other is for the right. Both of which were working perfectly. It was definitely the turn signal switch in the column. As soon as I started messing around with the hazard button, brake light function resumed.

On the brake pedal switch, that one was adjusted properly. I measured the signal with a test light and watched it blink on and off as I pushed the brake pedal.

This was a good learning experience for me. I could reason my way through a few tests to trace down the problem but eventually I knew it had to be something under the dash. It never occurred to me that a brake signal would be generated in the turn signal switch in the column. It makes sense to me now though. The brake circuit shares the turn signal circuit so something must control which tail light blinks while the other remains solid (like when you are stopped at a red light with your left turn signal turned on). That something has to be the turn signal switch.

Appreciate all the help. At least I know if I have the car longer than expected, I should just break down and get a new $50 turn signal switch.

[Chryco Psycho]

Exactly you had it 90% figured out on your own

[RUNCHARGER]

Great tutorial Slotts. This is something that should be checked on every single Mopar when we rebuild them.