Tail lights turn signal interfering with Valenti 4th Brake Light
 

Hey guys,

Throwing this out there in case there are any wire savy dudes that can help me out as I have found no threads with this exact problem...

So recently I ended up switching my tail lights from sequential Valenti’s to the OEM 17+ tail lights, and while doing so I had to rewire my 4th brake light to tap into the car side of the harness (as opposed to tapping into the actual tail light’s harness like I did on my last tail lights).

Now mind you, I am in no way shape or form even capable of understanding basic circuitry so please correct me if you read anything off, but I ended up switching my old cheap wire tap set up I had to a T-Tap set up with the crimps on them. And after all is said and done with wire figuring out again which wire connects to what, everything lights up as should.

The only problem being, when all the lights are on, including the 4th brake light, with either hazards or any turn signal, the 4th brake light lightly flickers to the pattern of the turn signal, nothing crazy but just noticeable. Never had this problem with my old set up before so I didn’t understand what changed.

I tried switching the turn signal relay under my dash to OEM (because I thought maybe it had something to do with my switchback signals up front) but then it just hyper blinks.

Anyone have any idea? Possible loose crimp? T taps are just shitty? Change in which harness I tap into (doubt it)? Anything absolutely different with Valenti and 17+ OEM wiring or bow signals travel to them?

Thanks in advance for any response and feel free to ask for more info that’s required.

Is the car running when you're testing this, or do you just have it 'On' but not started? If it's not running, try it with the car started. Loads with the engine off can cause lights to dim.

Personally, I never go with T-Taps. They are inherently a bad idea (in my opinion) because you are literally cutting part of the source wire apart. It's a blade that slices into it, making it more prone to oxidation and breaking. While I don't think that's the source of any of this, just wanted to throw in my two cents.

It could be other things as well, but I'll wait to see about that first question before steering you in potentially the wrong direction with wild guesses.

Hey brotha, thanks for the reply and insight on taps. I’d completely agree.

My original testing was with the car off, which your theory makes sense but just retried it again right now with the car running with the same problem ��

How do you have the 4th light grounded? Does it have it's own ground point or is it tapped into the tail light wires as well?

Correct it has its own ground point

I'm starting to think this is more car-side than it is 4th brake light. A quick test would be to turn on the passenger turn signal, then look at the driver's tail light and see if it dims at all with the activation of the turn signal. If it does, then we can stop looking at the 4th light wiring and move on to the car's wiring.

Also, where in the car harness did you tap in?

So the fourth brake light will flicker when either turn signal turns on, both driver and passenger side.

I tapped into the cars driver side tail light harness closest towards the end where it clips into the actual tail light

Does the driver taillight itself flicker at all when the signals are on?

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