2016 Tahoe HID Headlight Conversion

[JerseyTahoe]

I am a new 2016 Tahoe LT owner and so far my only complaint is the terrible headlights! Has anyone converted over to HID using factory GM parts? The headlight housings see to be the same at 1st glance for the Halogen and HID lights.

 

[Tahoe2017]

your housing are projector style the easiiest upgrade is LED. plug and play .
adding HID requires different harness, and power.

 

[cmatt]

Tahoe2017 is correct, the LS/LT headlight assemblies have halogen projectors in them. Outside of the bulb mounting differences (H11 for halogen & D3S for HID), the projectors may be designed differently for each type.

I have successfully swapped in OEM HID headlight assemblies in my 2015 SLT Yukon. I created a custom relay harness with OE connectors that addresses the circuitry differences.

In my opinion, the light output is greatly improved.


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[Tahoe2017]

please elaborate on the changes you did to swap in factory Hid.
stock headlights on these Halogen should never have been approved as sufficient lighting.

 

[cmatt]

Agreed. A lot left to be desired of them.

The primary challenge between OEM halogen and HID headlight assemblies is the way GM sends the +12v signal to power the lights. Halogen uses a pulse width modulated (PWM) signal and HID is a constant +12v. For halogen, the modulated +12v signal travels from the body control module (BCM) through the under-hood electrical center (UEC) to the lights. On HID, the BCM sends a ground signal to the HID relays in the UEC to activate them, which then send a constant +12v signal to the lights.

Halogen schematic

HID schematic

What this means if you just swap in OEM HID headlight assemblies in an suv that originally had halogen lights, the HID bulbs will flicker rapidly due to the PWM signal activating & deactivating the HID ballasts. Besides the light not being useable, the ballasts and bulbs will most likely wear themselves out quickly being cycled rapidly like that.

There are two ways to address the PWM signal. One is to have your BCM reprogrammed for HIDs. It will require you to send it off for programming and circuits at the BCM and UEC to be moved. Another is a relay harness which is the route I took. The PWM signal cycles so fast the relay can use it to energize itself. Then it’s just a matter of bringing the now constant +12v signal to the HID headlight. I created a relay harness that uses OE connectors for a plug & play solution. I build them just as GM does their harnesses for a factory look. The only sign is the relays mounted to the driver side fender.

Here is my Yukon with OEM HID headlight assemblies and Osram CBI 66340 D3S bulbs.

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[cmatt]

So I just made this great post in response to Tahoe2017’s question, hit reply and it’s nowhere to be found. Way to go Tapatalk. SMH


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[cmatt]

This is ridiculous! I just re-created the post via PC. It initially showed, but then disappeared. Any ideas? I don't think it's operator error, but who knows.

Anyway, to answer Tahoe2017 in a very condensed version, the pulse width modulated (PWM) signal used by suvs with halogen bulbs pulses fast enough to energize a relay. I build wiring harnesses for the 2015+ suv platform and created a relay harness for the OEM HID headlamp assemblies that is plug and play. In the harnesses I build, I use the same materials, wire gauges, connectors etc. GM does. In this case, the only thing noticeable is the two relays mounted on the driver's side fender.

 

[Tahoe2017]

This is not the most user friendly forum, terrible picture posting limits.

Question; ok so you are turning on your Relay with Headlight PWM drive signal?
So my question is Is the Daytime driving light mode signal, which is about 1/2 the frequency of headlights, does your relay pull in with DRL on which is basically lower frequency rate ?
and does your relay buzz with DRL on ?

 

[cmatt]

Agreed, it’s not very user friendly.


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[cmatt]

To answer your question, yes, I’m using the PWM to activate the relay. I’m doing this on a 2015 Yukon. It uses LED DRLs across all the trims. The headlights aren’t part of the DRL functionality like the Tahoe’s are.

Let me think on it. The LED strip on the Tahoe headlight should still illuminate since it has its own circuit. What I don’t know is if the lower amount of current sent to the halogen headlight for DRL functionality is too little to energize the relay. If that is the case, in theory, then it would allow to only have the LED strip active as a DRL.

I may PM you on this as well to sort out some details.

I tried to post the lighting schematics, but they have disappeared. Smh


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[cmatt]

@Tahoe2017 I sent you a PM, but that doesn’t appear to be working for me either.


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[73Vetteman]

You need to use a capacitor of 4700uf or greater to keep the relay from buzzing. The easiest thing to do is buy the code cancel capacitor that is available. You just plug one end into your truck's headlight wire and the other end into your HID relay harness.

If you want to convert your DRL's from headlight to LED's see my post about DRL mod.

 

[Team Mudshark]

LEDs will take over the world.

I firmly believe in the K.I.S.S. principle. Go to ebay and buy a pair of low beam LED bulbs. I use Lasfit. There are a bunch on there now stupid cheap. I don't trust them. Expect to pay about $32 now. I've upgraded my headlights several times over the last 13 years. The LEDs are a world apart. They come with a small fan built in for crying out loud. When I 1st hit the streets with these I felt embarrassed. I was now looking into the back rooms of my neighbors houses as I was pointed at them. These things are super bright and super white. Simple plug and plug as mentioned above. Save your money and don't bother with the high beams, You will never need them again. I went ahead and installed a pair of those too but I like the low beams better.