Valenti fourth brake light install issue
 

Last month while I was in Japan I decided to pick up a Valenti fourth brake light at Super Autobacs. This past week, my friends and I installed it together using a custom harness, where the harness takes the plug from the Valenti and then plugs into the chassis harness as well as has three signal wires that you splice into a couple of the usual wires to make everything work. I'm using the OEM 2017+ taillights as well.

Currently it mostly works fine.

In normal use, the reverse light works as it should, the V bar running light works normally with the running lights on; however, the the brake triangle only works about 80% correctly. It does the triple flash when I step on the brake, and that's ok. However, we've noticed that if I have a turn signal on, say at a left turn light and I keep my foot on the brake, then the triangle triple flash does one of two things: it either continues the triple flash multiple times until I let off the brake pedal, or that light just continues to lightly flicker a bit.

In the following video, you'll see what I mean... If I just press the brakes everything works fine for that part of the fourth brake light. The issues begin when I use my turn signal while braking, which is when the triple flash goes haywire and keeps flashing _or_ stops, but then the brake triangle flickers lightly.

[ame]https://www.youtube.com/watch?v=jz5wD4bIsl8[/ame]

We've double-checked all the wiring and the custom harness. Next step is probably to check if I can get the light to work with a different car. If the flickering/odd repeating triple flash issue continues there, then it's probably something in the light itself, maybe the LEDs or a bad solder?

I've been doing quite a bit of googling but haven't seen any related issues other than a couple posts here and there on the forums that some 2017's have bad/insufficient relays or similar, but that tends to be more of a taillight issue, not fourth brake light.

Another potential theory is that Valenti fourth brake lights sold in Japan are wired internally differently from those that we can get here from ft86speedfactory and other resellers. Which would mean figuring out what to re-pin or something to fix this.

@JeremyR and I are continuing to look into this but we figured we should start a thread and see if anybody else has experienced similar or has other ideas of what may be going on.

Thanks in advance!

I remember modifying my V-light a few months back and switching up the wiring inside so the V-Light can turn on independently.
Looks to me like like the brake light wire coming from the V-light is sharing the same wire as the turn signal. Once I opened the light assembly I was able to have a better understanding of how to wire it up.

I'm thinking we might have to open it up as well!


We tried a number of different things but nothing has made any difference.




The Valenti is wired the same way as shown in this thread:


https://www.ft86club.com/forums/showthread.php?t=114591


Using a "custom" harness so no wires on the car had to be cut or spliced into.

hmmm, that's not the flickering that I thought it was when we discussed it. My troubleshooting ideas that I suggested won't work for that, at least I don't think it will.

Everything was done correctly with the install, we even tried messing with the wires and I electrical taped a couple things that I thought MIGHT be an issue but it didn't make any difference.


The valenti also came with it's own relay, but spike confirmed switching that out made no difference.


I'm guessing that because his is a JDM model that maybe the internal wiring could be different.




My other suggestion was to try connecting it to another twin and see if the problem still persists. If so, we probably need to crack it open and re-wire it.

I had suggested to remove the "custom harness" and run some really long wires directly from the unit to someone's car's battery parked behind him. But that's when I thought it was a dying LED flicker rather than incorrect flickering.

Welp, yeah, I made that video after mentioning it to you.

Connecting it to another car is probably good at least for process of elimination. But the more I think about everything and dig up old (taillight-related) threads, the JDM vs USDM wiring spec theory makes more sense.

Maybe @xenarc is onto something and the turn signal wire is being used for power or something where it shouldn't be, inside the housing. Well, where it shouldn't be for USDM. Maybe the pin out is different for JDM spec and it shouldn't be tapping into the turn but it is anyway?

Wish I was more of an electrician than software engineer right now. :iono:

What about bypassing the custom harness, and use wires with posi-tap connectors to connect to the taillight? I know you were trying to avoid this, but this way you can control what lead goes to what source. Posi-taps are easy to use and are minimally "invasive."

i hate IDC splices. nearly 3 years of my electrical career involved fixing them.

IDC???

it's what Posi-Taps are. Insulation Displacement Connector.

https://en.wikipedia.org/wiki/Insula...ment_connector

they work mediocre in telecom, where all the wire gauges are standardized, very low current, semi-water resistant, generally use solid core wire, and vibrations are kept minimal.

but move past that, and IDC's tend to cut too far into stranded wire, lowering the current capacity of it while also creating a breakage/vibration issue down the road(the entire reason stranded wire is used in cars is to reduce vibration/breakage issues), as well as allowing an ingress for water which starts corrosion issues. certain one's are claimed to be waterproof, but my experience has those somewhere near a 60-70% failure rate.

Ah, I see. My soldering skills aren't the best, so I'd trust them over me soldering. Haha

crimps are the best option. soldering literally converts stranded wire to solid wire, so vibration/breakage issues arise at the solder joint.

The harness came from autoharnesshouse, who has a great reputation in the Subaru community so I doubt it's the harness.


I do have a spare harness we can use as well to try and rule out if its a bad harness.


Cutting into the stock chassis harness should be our last resort in fixing this issue.