Tail light issues

[Sir Keppa]

Sorry for the following, maybe confusing text but i am kind of depressed. 

I spent a few hours on my 70 Challenger this weekend and tried to get rid of some electrical issues i had since i bought the car.
One of the remaining problems is the flasher.
I installed a brand new tail light harness from YearOne (the old one was corroded on every single bulb socket), i renewed and cleaned all the body connectors at the driver side, i refurbished the headlamp switch and polished the inside contacts, found a cut wire at the directional switch and fixed that...problems still remaining.

When turning on the right flasher, the indicator gauge lamp wont light up and the front parking light stays constantly on - tail light flashes slowly. I had the the parking lights out allready, as well as the gauges.

After installing the new harness i have new issues with the tail lights too. First only three bulbs reacted.
After playing around the very left tail bulb constantly lighted up in the brighter flasher configuration till i removed the bulb and put it back into the socket. It went back to the standard darker config but still lights a bit brighter than the other three bulbs..
Then i removed the tail light housings and connected the sockets directly to the body which caused a slightly better distribution of light. Still the way ich connected the sockets to the body was not perfect.
When i turned the right flasher the two left bulbs started flashing veeery slowly.
When using the left flasher it will start flashing after 5 seconds, first veery slowly and then increasing the speed with time...
Long story short - i am confused!

At this point i would guess its very bad grounding at the tail housings and maybe bad grounding at the left front as well?
The very different kinds of issues are very Strange for me.
Is it possible to install the 2-pin bulbs wrong?
I dont know how i could improve the grounding or maybe i am missing a grounding wire at the housings?
The new taillight harness sockets have a male connector which the OEM one does not have. I assume its an option to add ground wires...so maybe my problems are common ones?
When i tried the hazard light a year ago it ended up with a completely burned and smoking hazard relais...

[71vert340]

Electrical issues are the most time consuming and I know what you're going through. The first thing I would do would be to check my grounding to each light housing using my volt/ ohm meter. Clean all the ones that show any resistance higher than a few ohms. Sometimes it's easier to accomplish this by running a test wire from the car's body ground to the volt/ohm meter black lead and touch the other lead to the housing and get my reading. Do this on each light housing and get all good grounds, then see what you have.
Terry

[Cuda Cody]

Ground or short. 

[benlavigne]

Hello,
I just replaced my rear light harness on my 70 Challenger also, and noticed some gremlins after that, brake light would not work after I turned on the lights, etc... When I removed the old harness, I noticed the previous owner had put some crude wiring from one socket to another and then to a stud on one housing. Since the new harness did not have these wires, I did not replace them. This PM, I fabricated a wire with female connectors and a grounding ring at the end to ground the sockets. It seems to have cured the issues at this point...

Ben

[Rich G.]

Get a long piece of wire and connect it to the neg terminal on the battery and then connect the other end to the housing on the light that's giving you the problem. If the problem goes away then you know it's a ground issue and then you just to figure out how to correct the ground issue. It's also common for the wires to be crossed in the socket causing the wrong filament to light up.

[Sir Keppa]

Thanks guys! I think i will try adding a ground wire before checking ohms.
My question now is how the housings suppose to be grounded on the body? Should the studs ground at some unpainted spots?

[aussiemark]

I have heard about some poor quality with the repop harnesses from people who have bought them, things like wires crimped only on the insulation and not on the copper wire and I did hear of an incorrect globe holder dual filament where a single filament was supposed to be (or vise versa I can't recall). My advise is to check each wire for continuity and carefully examine all connections to make sure they are good and make sure the globe holders are for the same globes as original. Don't just fit it as if it were NOS although they may have problems they are better then nothing or corroded old wiring.

[dodj]

Thanks guys! I think i will try adding a ground wire before checking ohms.
My question now is how the housings suppose to be grounded on the body? Should the studs ground at some unpainted spots?

Yes.  The housing mounting studs are supposed to provide the ground.  A separate dedicated ground can alleviate a lot of electrical issues. 
I added extra ground wires in mine for tall lights,  dash switch panel,  and engine/vr/ecu. If you don't like extra ground wires,  you need to make sure you scrape paint or use star washers.

[Sir Keppa]

I have heard about some poor quality with the repop harnesses from people who have bought them, things like wires crimped only on the insulation and not on the copper wire and I did hear of an incorrect globe holder dual filament where a single filament was supposed to be (or vise versa I can't recall). My advise is to check each wire for continuity and carefully examine all connections to make sure they are good and make sure the globe holders are for the same globes as original. Don't just fit it as if it were NOS although they may have problems they are better then nothing or corroded old wiring.

From what i know the repop harnesses from YearOne are made by H&M and should be good quality. I also red about poor quality ones too from other manufacturers tough.
The harness i have here appears to be very solid and clean made.
Anyway i can tell that some bulb sockets need to be modified to ensure snapping in the locked position.
I think that was my problem with the wrong filament lightened up.

[HP_Cuda]

Not to say you are not on the right track but also be aware of the turn indicator switch in the column might be giving you issues at the same time. Don't ask me how I know....

[aussiemark]

I checked the Year One harnesses I bought for my 70 Cuda and all the visible connection look good

[RUNCHARGER]

Pull a few connectors apart to isolate circuits then work front to back or back to front. It shouldn't take long to find.

[Chryco Psycho]

Are the Flashers new now ?
I have seen poorly made bulbs with reversed filaments so the bulb goes in right but the wrong filament lights up

[Sir Keppa]

I disassembled the tail lights last night and found quite some corrosion at the grounding points.
Cleaned everything, removed the paint from the stud points and used a good amount of conductive grease.
The lights now shine brighter and equally.
So far so good but the problem with the flasher still remains.
The flasher will work until i turn the head lights on. The flasher then stops like it has too much restistance.
Havent checked Ohms jet...
I am waiting for a new front light harness since the factory one is pretty much corroded.
If i cant fix it with that i will remove the dash harness and start another little project i allready had on my list: unwrap the dash harness and check for breaches or melted areas.
YearOne offers different harness tapes but i wont see my car for the next 2-3 weeks.

Could someone please tell me the correct width of the factory tape for the dash harness?

[Chryco Psycho]

Still sounds like a ground problem , if the turn signals work ok with the headlights off but quit qhen the headlights are turned on this usually means the turn signals are grounding through the headlight circuit , as soon as you put power through the headlight circuit it cannot ground through that circuit , once you have a proper ground at all of the lights front & rear the turn signals should work just fine . So this makes sense that you have found a lot of corrosion in the light sockets & they cannot ground properly