14/15 silverado - adding foglights

darkfox1 · March 1, 2015

Easier yes, but my truck is my only daily driver. I can't be without it.

Plus there's the hassle of getting it out of the truck, and the risk that some grumpy GM tech is gonna flag my truck and void the warranty if the code doesn't match in the bcm.

GTPprix · March 1, 2015

Easier yes, but my truck is my only daily driver. I can't be without it.

Plus there's the hassle of getting it out of the truck, and the risk that some grumpy GM tech is gonna flag my truck and void the warranty if the code doesn't match in the bcm.

You can take it out in about two minutes with no tools oh and the programming is invisible at the dealer level ;)

darkfox1 · March 1, 2015

I've been doing some more reading/digging and I don't think the parallax unit will work for what I'm trying to do. The goal here is simple for what I'm gonna call "plan C" for now.

Plan C requirements:

* Pull accessory power that wont confuse or break the BCM

* Does not remember previous state (like factory behavior) upon loss of power

* Uses factory momentary foglight switch.

* Works independently of headlights, drls, high beams, turn signals, brake lights and BCM.

Plan C initial concept:

* Use factory cigarette lighter plug to pull very low amp load through relay/circuit to "flip flop" on/off using momentary switch.

* flip flopped relay outputs to automotive relay that is "given permission" to turn on

*Automotive relay pulls in from 12v non-accessory fused at 15a

The parallax unit in the demo video is NOT using a momentary switch but a push button latch switch. I could be wrong here but I'm 99% sure the factory foglight switch is a N.O. momentary switch. Without looking at pinouts it will either have 1 or 2 pins for the foglights that the factory non-foglight switch doesn't have. Comparing them side by side should make discovery easy.

The easiest way I can see to do this is with a microprocessory style "flip flop" circuit.

Something like this perhaps:

http://www.mcmelectronics.com/product/28-5115

accessory power comes from the cigarette lighter, on/off comes from the facotry foglight switch, output goes to an under-hood relay that pulls power from 12v batt. and standard chassis ground.. goes down to fogs.

This accomplishes the goals of plan C from what I can tell. Costs a bit more than initially thought but.. its a small cost.

darkfox1 · March 3, 2015

OK, so I have good news, not so good news aand bad news.

First, good news. I got some goodies in!

The fog light buckets, bezels, bumper harness and foglight switch came in.

This is the bumper harness. It's not clear if I've ordered the wrong one (the PN cited was for a truck that came w/ fogs w/o sensors but this harness has pinouts for sensors as well as fogs.) It comes with the mounting clips already on it which is refreshing.

This is one of the foglight ends. The "connector" translates this into a standard bulb socket connector that interfaces with the foglight. If you dont already have connectors with the fogs you wind up with you will need to buy them. The GM version is crazy expensive for what it is. Something like $50 EACH! If you're a brave soul who is not afraid of a soldering iron you will save a bundle to go to autozone and buy the proper bulb connector and chop this off, its literally just a translation. Why did they put the wrong connector on here? It makes no sense!

This is where the bumper harness meets the forward lamp harness. 2014 silverados like mine that did not come with foglights do not have the other end of this, and need the forward lamp harness to interface with this. Without confirmation, I assume the top row are sensor pinouts and the bottom 2 are probably foglight pins.

This is one of the foglight buckets. This attaches to the brackets inside your bumper, not the bumper directly. There are 3 holes in the back about the diameter of a thick pencil, these are where your foglights mount.

A foglight bezel mated to a foglight bucket. The bezel attaches to this with clips. It also has places for bolts on either side but they do not appear to go through the bucket.

All these parts came without mounting hardware btw. I will probably run to a hardware store to pickup the bolts I need, rather than going through the dealer.

The not so great news: This is the back of the foglight equipped headlight switch. The pinout is the same as a non-foglight switch, so that's fun. Same count, same positions. That means the non-foglight switch has the same circuit, but is missing the NO momentary switch logic that turns the foglights on and that's all. The switch I ordered is the correct color for a silverado. (Blue.) I was told however from dealers that it may also work with Sierra. Why? Aren't those red? Hrmm... Sierra guys, take this information in note, you may need a different switch if you dont want a random blue switch in all of your red interior.

The bad news: my foglights do not fit.

My research pointed me toward the 2008-2013 silverado fog lights for my project. Though they appear to work in the '15 silverado and are the same SIZE as the 2014 fogligths, there are tiny differences. This could just be a horribly made product, but even when I get the pins to line up, the foglight is terribly out of alignment and pokes through the bezel. Still.. I paid $42.99 for 2 fogs and the connectors, which normally cost about $50 each. I still came out ahead because I have the connectors at less the cost, and this was worth the trouble. The bad thing is.. we won't be installing these this weekend like I had anticipated.

Forcing the foglight proved less than fruitless. I could have resold these to an 08-13 forum member.. now I just have 2 pieces of plastic.

If anyone wants these I'll be more than happy to recoup some of my money and sell them to you on the cheap.

In all liklihood they will fit a 2015 tahoe if.. you can fix this one piece I broke off. :S

darkfox1 · March 3, 2015

So the next step is trying to figure out how to go with what we've been calling "plan C."

Now I've installed the switch already and as expected, putting the multimeter on the fuse line and listening for a relay click proves to be in vain. Even though the wiring is there all the way to the fuse, the bcm is not telling it to turn on. MOST LIKELY I imagine, because the bcm wants to know if a bulb is out or not.. and if it was listening on a dead line, it'd flag false errors.

So I've been looking at the wriing. There's a 12 pin harness coming off the headlamp switch which leads to a pcb inside the switch, the monetary switch is on the pcb, and this runs to connector X1 on the bcm, more than likely its a direct run.

One thing my father and I have been discussing the last 30 minutes is the voltage of the momentary switch. Since the switch is a pcb and goes through the bcm its unlikely to use a 12v source. My flip flop relay circuit that I ordered requires 12v to pull in.. so...

X1 has a 5v "reference" pin, which I'm assuming is the voltage the switch is pulling.. and well it doesn't take a highschool graduate to tell you that 12 is greater than 5, so even if I hacked my way in and wired this up.. I'd still get nothing.

I've been trying to find a pinout diagram of the headlamp switch on upfitter, nothing yet. It's unlikely that I will, but the X1 connector seems like the best bet since almost all of X1 deals with headlamps, fogs etc.

Essentially, these trucks are not like your old chevy with the glass tube fuses that transmits 12v everywhere. This truck is a rolling computer with a masterfully planned and highly complicated electrical system that.. quite frankly.. I'm starting to feel uncomfortable tampering with.

So that kinda leaves me with 3 options.

1. Diode jump the BCM output so that whenever headlights are on, fogs are too. Messy, works, no control.

2. Wire in a momentary switch that DOES work on 12v, or even a rocker switch that bypasses the need for flip flop, put the old headlamp switch back in (now that I fixed it.. I broke it a month ago when I hit it with my knee and didn't even know until now. I knocked the bar out of it so it didn't click when it rolled.) Not as messy, with a momentary switch it'd have stock like behavior but be independent of all other lights. Ugly though, gotta cut my dash and wire a switch somewhere.

3. BCM repgrogram. Best option but price and requires extensive downtime on my truck, which means I'd have to rent a car at over $100 a day, AND risks voiding my truck's warranty. Up side: 100% plug n play, exactly like factory or better, uses all factory wiring and switches.

darkfox1 · March 4, 2015

Well, after a night of frustrated googling and being "sure" these lights will fit in these buckets, double checking my Part Numbers and looking at other forums for tahoes and silverados I am convinced these are the right fogs.

So.. I went out today and grabbed them and tried again. Lo and behold, the one that wasn't broken snapped right in! With one pin.. however.. looking at other "stock" foglights for these trucks it seems they have 2 options. One with these clips, one with rubber retainers. So I clipped it in and put the trim over it.. and its in there!

So I've busted out the gorilla glue on the other one and we're gonna see what happens.

Ghetto? You know it! But if it saves me over $200 for the same part just because moisture warped the product (it was POURING rain yesterday) then I say lets give it the benefit of a doubt. These ARE the correct lights! I'm convinced of it.

Pics coming soon. One of them is sitting assembled on my coffee table, the other is in the kitchen with a gorilla sitting on it.

darkfox1 · March 4, 2015

Whattya think about this bad boy of an idea? Ya reckon these are 12v momentary switches?

http://sandyblogs.com/techlink/?p=3450

darkfox1 · March 5, 2015

Proof of concept for the foglight. (blurry.. meh.)

The aux switches won't work because I do not have the upfitter RPO code. They wont work for the same reason the factory fog light switch wont work.

"plan C" is quickly becoming cost prohibitive.

I still need to buy the small bolts for the bezels and buckets (and the washers that go with em.)

darkfox1 · March 5, 2015

Good news everyone!

Possibly.

I just did some calling around. I spoke to a rod shop that can "modify anything" and a chevy dealership (the dealer I bought the truck from.)

The service guys at the closest dealer had never heard of doing foglights and weren't super helpful, however, the service guys at the dealer where I bought the truck did some digging, called GM and said that it CAN be done.

Cost is $175 and they would need the truck for a full day to basically download and install the BCM code, updated to allow foglights.

Whether this is real or not is yet to be seen. They may take it in, look at it all day, then give it back with a "sorry, we was wrong." but.. it's worth a try!

My forward lamp harness will arrive Saturday. This is the "final piece" I need to install this if I am going the OE route (which I very much want to do.)

The only thing I DONT have yet are the screws that fit into the foglight buckets.

darkfox1 · March 5, 2015

I was watching a video today about bumper removal and noted that the small 7MM bumper bolt located in the wheel well looked to be a perfect fit to the foglight bracket holes.

I rushed out to the truck with my drill and took it out and it fit!

So.. I took the part down to my parts department and pointed to it with the help of my vin.

The bolt is PN is 11589015. They cost about 68 cents each and you need 10 to install the lights, based on the number of holes in the buckets and the bezels.

Spurshot · March 6, 2015

https://www.youtube.com/watch?feature=player_detailpage&v=IEoV_7cIsKQ#t=162

darkfox1 · March 6, 2015

This monster is the forward lamp harness. The orange and blue connector is connector X1 for the X50 under hood fuse/relay box. You will have to remove your fuse box to install this.

This harness replaces the current harness for the headlamps, turn signals, drls, windshield washer bottle and some other misc. items.

There's a rather large connector on the passenger side that I'm not sure about.

The important thing here is that it DOES have the output in the center for the foglamps.

Here is a pinout list:

darkfox1 · March 12, 2015

I have all the parts I need. I've been waiting on dad to come up to help me do the install. He was planning to come up tomorrow but he fell and hurt his arm. The med-now says he may have a hairline fracture in his arm. So I dont know if hes coming or not.

I could probably do this by myself, but I wanted someone to at least hand me tools.

I've done some looking at the forward lamp harness, and thanks to some members here who have gutted their front ends for light bar projects I've gotten a good look at it. Regrettably, removing the grill and bumper and all doesn't look like it will be enough to access this harness cleanly. It mounts on the k member behind the radiator, so we may need to drop the skid plate.

I'll try to document everything with photos and build a how-to for all this in a single post when it happens!

Spurshot · March 13, 2015

The "skid plate" is simply a plastic shield held on with a half dozen bolts.

darkfox1 · March 13, 2015

Right. I'm not really concerned about having to remove it.

Also, once we get the bumper off front end clearance will be such that we PROBABLY wont need to have the front wheels off the ground to get this done.

Good news: Dad's arm is fine. Bruised and arthitic but not broken.