Headunit dimming (night mode) when pressing brakes.

Another thought in case that last idea doesn’t help. Under the rear of the bed, up in behind the bumper, are two connectors feeding the trailer connector. Those could also be unplugged temporarily to see if there’s any change.

 

I had a chance to disconnect the taillights individually to try and chase this down. Disconnecting the upper lights and reverse lights results in no change. HOWEVER, disconnecting either of the left or right brake light bulbs puts the headunit into night mode (HU LEDs are turn on and Android Auto triggers dark maps). So, it doesn't matter if the left one is disconnected and the right one is plugged in or vice versa. If one or both are unplugged the headunit goes into night mode.

I'm guessing they activating the brake lights is doing something similar to disconnecting the bulb. The bulbs are Sylvania halogen 3157 bulbs. Not sure why the (supposed) random voltage dropout under braking (if that's what it is).

 

Have you replaced the rear stop/marker bulbs since the truck was new?

This may be a stretch but in 2014 front turn signal and rear stop/marker lights were referred to as 3157CK bulbs.
Now they show to be 3157KX in the manual, which both it and the CK (I think they are the same) are different than a standard 3157.
The sockets are pinned differently than the standard 3157.

Explained here;
3157 VS 3157CK LED Bulbs — AUXITO



Instead of turn in this diagram, refer turn to brake/stop.
So it might be when you hit the brake, you are activating, somehow grounding, the parking circuit.
But it's confusing that you pull the bulb and it goes into dark mode.

 

I actually did. I figured all 3157 bulbs were the same. WTF? These are

$20 Sylvania 3157 ZEVO LED White Bulb - Bright LED Bulb, Ideal for Daytime Running Lights (DRL) and Back-Up/Reverse Lights (Contains 2 Bulbs)

Sylvania 3157 long lasting bulbs from AutoZone

So which 3157 bulbs do I get?

 

I tried the Sylvania ZEVO LED bulbs (from AutoZone) that are listed as compatible for our trucks, and both left and right brake lights flash in unison when either turn signal is activated. On top of that, the head unit starts up in night mode as if there isn't a bulb installed (pretty much no load detected).

I'm even more confused. Why would the LED brake light bulb flash if the turn signal is activated? The halogen bulb didn't do that, and putting the halogen 3157 bulb back in is "normal" (other than the random flicking night mode head unit bug).

 

These are the old brake bulbs out of my 2014, I run VLEDS LEDs in a Hottails kit now.

They appear to be 3157KX.
The KX designates the way the socket is pinned as in my reference in my previous post.
I think when you hit the brakes with the standard 3517 bulbs, it grounds (or powers) the illumination circuit and causes you HU to think the parking lights are on.

As previuosly stated, the weird part is why the HU just flashes.
it seems your HU would be dim as long as you have the brake depressed.

 

Wow, I've tried several rear LED bulbs over the years and none did that.
I can't remember if you posted, are you using stock halogen front DRL/turn signal bulbs?

 

Front is the OEM LED set with the plug and play harness.

 

How long ago did you do that?
Is that when this issue started?
Who made the harness, @iHacker or headlight revolution?
I'd bet your flashing of the rears with LED bulbs happened after you did the headlights.


Maybe try unplugging the headlights and see if the HU still has the issue.

 

I upgraded the LED headlights back in June. The harness is from Headlight Revolution, but the headunit didn't do the flickering until a week before I posted this issue. I'll try putting everything thing back to stock and testing things one by one. Ugh

The thing is I'm not the only one with these OEM LED headlights and the harness, but I'm the only one with this odd issue.

 

Maybe leave everything as is, start the truck, and test all your lights.
Parking, turn signals, brake, DRLs, white strips of the new LED headlights.
Have someone outside the truck that can verify everything is working properly.

I doubt you have the stock rear bulbs, I'll send you my 3157KX if you want them.
May not fix the issue, but it might.
I don't need them anymore.
They're already sitting here on my desk..

If you want them PM me a name and shipping address and I'll get them out to you.
I'll cover shipping..

 

I think I talked about this issue before in other threads.


https://youtu.be/xPZbmI4QMQg


Start watching in the minute 4:35 where the turn signals parts begin, they are wrong when suggest to switch pins White/black wire with the Purple wire. Your truck has to have only the 2 wires as they are showing in the video and instead of inserting Purple wire in the center hole just cover the metal contact in this wire really well with electrical tape and leave the purple wire out the turn signal plug. Fill the empty center hole with silicone to keep water out and this should work to fix your problem with the taillights.

 

There’s nothing wrong with your head unit I guarantee you that and the problem is exactly where I pointed. The new bulb 7444NA has the ground contact flipped so when you use the turn signals it will short your taillights circuit. And this is in all the trucks that followed HR instructions and is just a matter of time you will notice that if you pay attention to your head unit and dash lights.

 

So, even though I have 3 wires, instead of swapping the pins like instructed I should have just left the purple one out?

 

Yes sir, you have to leave the Purple Wire out of the turn signal plug

 

Welp. I'm going to try this tonight.

 

I'm gonna hold on shipping you the 3157KX bulbs until we see if this fixes the issue.
Let me know how it goes

Thank you @iHacker
I knew there had to be a cross/short somewhere.
So this also affects the HU when he hits the brake?
When he mentioned HR, I figured that might be the issue..

 

OMG I think this did it. Headlight Revolution and all the LED harness makers need to update their instructions. I'm going to drive it for a bit to see if this fixes it.

Put the ZEVO LED lights into the brakes, and they don't flash when turn signals are activated either.