Hunner headlight switch mod

:emb:The switch came up in my bumper thread, and 4Speed mentioned wanting to find out about eliminating the spring back from OFF. I too often want to turn off the lights and have them stay off when offroading so my alternator is being directed more to charging. Makes better pictures too especially if you have a point and shoot that meters the lights and darkens your pictures. Gotta have trip pictures!
You can also run in stealth mode of any combination of accessory lights.:shifty:

IMPORTANT! I still have not modded or installed this. I don't know for sure the affect the switch remaining in the OFF position will have on anything else. As it is, OEM it is only there momentarily. I need to check to see if a relay is involved. The smoke test has yet to be performed and consultation with a particular electrical engineer.
Stay tuned!

Since I had one out I thought I would dissect it again and see how this thing works. I still have to experiment some more and figure out the non-destructive way to remove the module from the dash. I hate pulling until something gives.
Anyway, I will start with the basic module and get this started before I forget the procedure.



I found the contact wiper was a one part piece. So the knob had to come off the front. There was not room under the edges.
I popped the cover off by prying these tabs so I could get a screwdriver under the knob and gently equally around the edges lift it off. fail!

I was watching for stray pieces and when it came off but the spring with a bullet end popped up and stuck in the liberal amount of grease present.
I then noticed this small brass piece laying on my work surface? I'm still looking for where that was:whaa:
May have to wait until I dissect the one in the H3 and watch for it.

This appears to me how it functions. When the spring is in place in a molded in tube to the left of the knob shaft

it rides over the dentents on the lower area of the assembly to hold it in the various positions.
The spring back from OFF happens when the spring assisted bullet rides up the ramp I marked in black and slides back to the "auto" position.

I believe a little creative Dremel tooling could eliminate that ramp but a detent area would have to be formed for it to stay there when switched to OFF and remain there. Then leave the spring device in place so the switch positions are a positive position.
Whaduthink?
Still better find out more about what being in constant contact with whatever turns off the lights might do.
More research needed for the actual implementing this.

If the lights take away from the generator keeping the battery charged it is due to other problems in the electrical system. In fact, for those who tow a trailer with a battery pack installed, it is common knowledge to turn ON the headlamps to pull the generator up to a higher output to allow more current to flow to the charge wire, from the vehicle to the battery in the trailer. The normal output is just a trickle, the lights on boosts the output of the generator to increase the current to the trailer battery.

If the momentary drop in headlamp output at night, when the brakes are applied, makes it appear the generator is hurting, it isn't. It has plenty of oomph to charge and keep the system running. The PCM is programmed ramp up slowly when a large load is applied (brake lights is one example). A slow ramp up (a second or two) vs. an instant ramp up, saves on the generator and allows it to last longer.

Now, if you are running the winch at max load during the night, yes, turning off the headlamps would be a decent idea. In fact, turning off the DRL headlamps during the day when running the winch would be a good idea too.

I do understand the need for stealth at times; used it a few times myself, but the ignition cycle off worked ok for any of my needs.

As for the BCM, I have no idea how this would affect the BCM. It was designed as a momentary contact to signal the BCM to turn off the lights. And honestly, have no idea what would happen if this momentary contact was made into a full time (at least for long as you placed the switch in that position). Needless to say, when at GM we never tested for this. In fact, until today, never thought much about it.

Sorry, could not be more help.

Thanks for the reply. I was not too worried about the alternator keeping up with the lights. I remember your info on that.
It was brought up about doing it and for the other reasons stated just thought I would check it out.
If that switch signals the BCM to perform the action, it might be best to just leave it alone!
That was my concern that being full in contact with whatever shut them off might be a problem and I don't want to create more problems.
Might just hold off on that experiment.

Heck, BCMs are only about 350.:gaah::giggle:

I love this type of research. It's the type of things I would love to do if I had more time or the right workspace. Living in an apartment with a 3 year old is not very conducive to this sort of stuff. Thanks to both of you for all this great R&D.


"Ex Umbris Venimus"

f5moab said:

Heck, BCMs are only about 350.:gaah::giggle:

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I have just about everything else! I just ordered another light switch so I can hack this one at some point but the guy did not have a BCM.
I guess they have to be flashed for the vehicle?

ReconH3 said:

I love this type of research. It's the type of things I would love to do if I had more time or the right workspace. Living in an apartment with a 3 year old is not very conducive to this sort of stuff. Thanks to both of you for all this Greta R&D.


"Ex Umbris Venimus"

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Just shows what can happen when an over active mind is bored!!:shifty:
I know you can't stuff a chewing gum wrapper in to replace a fuse anymore, like I was shown at a young age on a Ford tractor, because the wrapper is not real tinfoil anymore, and I know enough to ask for professional help when I see technology has interfered with the Farmer Fix!
I carry an extra headlight switch for that reason. Another good reason to have aux lighting and other redundant systems.

Ok to redeem myself I carefully dissected another switch and this time saw that the small brass disc was on the bottom of the interior light override push button.
Just in case someone was brave enough to try the mod.
I don't know the outcome of modding the spring back feature on the headlights for sure on other components and not sure who would know that without a "smoke test" lol

Hi Hunner, on the south african units if you turn it to the off position, it stays there, so I presume we have a slightly different setup to yours.

Well that could be a solution. Order a SA light switch, problem solved! They must figure you guys are smarter than us and can remember to turn your lights off and on!!:giggle:
Where do you get parts when you need them? If you have a dealer over there try to find out the part number for a light control switch please.
This is the first vehicle I have owned that tries to think for me. I still TRY to turn them off and on when I get in.
I have to switch habits when driving my 95 Dodge Cummins, it does not think for me.

We order parts at our GM dealers that bought the rights to sell Hummers in South Africa, so not a lot around. My Hummer is going in next week for service, then I will do the enquiry.

This is what our switch looks like: Auto in middle, then park lights to the right and to the far right off

Interesting. Of course it would have to work with our BCM set up, so I'm not sure about that.
I notice it does not have Onstar on that model.
See what they want for one. I have found the model we have here for as cheap as $10.

Hunner said:

Interesting. Of course it would have to work with our BCM set up, so I'm not sure about that.
I notice it does not have Onstar on that model.
See what they want for one. I have found the model we have here for as cheap as $10.

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The BCM interface might be an issue. And ja we dont have on star this side or xm radio or any fun stuff :gaah:

10$ is roughly R90, and if you think that GM charges R350 ($38) just for a replacement headlamp bulb you can imagine what they migt charge for this unit....

I have a friend that knows of a junk H3 will ask him if the unit is salvageable. even if you then just strip the unit and use the non returning disk on yours it should help :wink:

Bingo. Looks like the SA switch is the way to go. Killing the auto-headlights is great! Killing the On-star is even better!

The missing button on his is the Blue Tooth button, although it does also activate some functions of Onstar

I believe Hunner has an 08, thus he never had the bluetooth system module attached to the onstar module. In later years, after bluetooth was added, it is still considered an Onstar button since you are going through Onstar to connect to the bluetooth module. On my silverado it has a similar button in a different location, and when I press it is asks if I want bluetooth or onstar.

Did anyone ever get this to work? Did using the SA switch work? Anyone know the part number for the SA switch?

https://www.amazon.com/ACDelco-D152...21&sr=8-1&keywords=hummer+h3+headlight+switch if you refer to the picture it shows the SA model, its 32 bucks on amazon and its prime, might be worth trying!

Kyle said:

https://www.amazon.com/ACDelco-D152...21&sr=8-1&keywords=hummer+h3+headlight+switch if you refer to the picture it shows the SA model, its 32 bucks on amazon and its prime, might be worth trying!

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I have my eye on that. Thanks. I have to first figure out if my switch is a 14 or 16 pin. The SA one is a 14 pin.

Hello! Once you remove the knee bolster and the screw under the switch, does the switch just "fall out"? I'm replacing the bulbs in mine and I see lots of pics or the switches removed but none of the actual process. I've come across some diagrams tho and just want to make sure it's as simple as it seems. (things rarely are!)
Thanks!