14/15 silverado - adding foglights

[TJay74]

your only problem will be the BCM, Chris will be your only hope as the dealer is not able to turn on/off features in the BCM. They can only flash your BCM exactly as it was optioned from the factory, they cant substitute in another VIN to activate options like they did on the previous years. Also if Chris fixes your BCM for you and there are any factory BXCM updates for your BCM I would be worried that the factory update will delete Chris's mods and then you would have to ship your BCM back to Chris again.

 

It is not as simple as it was on the 2007-13 trucks, the new global architecture GM uses now has taken those options out of the dealers hands. I have spoke with the GM engineer about this in detail here recently.

[darkfox1]

What about buying a BCM that already has the option turned on? I had to buy a new BCM for my 2000 camaro a couple years ago because every time I hit a bump the radio would go out. Cost about $100 or so and was a pain to install, but it worked.

 

I tend not to go to the dealer for anything unless there's a real problem or I'm buying a part or checking on something.

 

I wonder how hard it would be to bypass the bcm to wire these...

 

I mean personally I don't care if they even work, but if I go to sell it or something.. selling a truck thats junked up with non-working parts is kinda ghetto.. I'd want them to work for the sake of resale.

[darkfox1]

Looked it up, a replacement BCM is about $74 and shipping from GMPD. You figure around $100 or so.

 

Called a local service dept. and they said they didn't really know if the bcm had to be reprgorammed, but seemed to think they could do it. I asked about the fog light relay. He said he thought it wouldn't be there and when I pressed for details of where it SHOULD be he said "I don't know I've never done this" and was done with the call.

 

I might ride out this weekend and see if a dealer will let me see under the fuse panel cover on a 15 on the lot with fogs. I gotta find that relay. Seems like all the wiring is there cab side, just not past the fuse box. Which is more than likely where the forward harness connects.

 

newgmparts shipped today. Should see the first major batch of parts mid/late next week. GMPD is still on order, may be the week after before I get the forward lamp harness.

[darkfox1]

Because that's how gm handles options.

 

Where can I email you about this? Your pms are full.

[GTPprix]

Find my website, I'm not exactly hard to find ;)

[TJay74]

Chris might have to verify, but I bet the BCM ships unflashed. The once installed the dealer hooks up to the GM global system and once your VIN is verfied the system flashes the new BCM with the most recent calibration GM has for your VIN/truck.

[darkfox1]

That makes sense I guess. I dropped Chris a line on his website (I think) for more information. So what would I have to do.. drive to the dealership, have them program the new bcm, THEN take that bcm back out and send it off?

 

Sounds like they do this on purpose to make this more difficult.

 

I CAN jump the wires out and bypass the bcm I imagine.. I'm not sure how to do that just yet but.. I mean thanks to the foglights always on thread, I could use a diode to force the fogs to be always on with the headlights and wouldn't even need the switch. I dont know how that would behave with DRLs though.

[TJay74]

Yes correct, if you want his programming to stay I am guessing he would need to re-flash his changes if the dealer flashes your BCM for any reason. Plus the truck is not driveable while the BCM is out.

[darkfox1]

Well if ya have 2.. one thats flashed for your truck and one thats custom flashed, you take the custom one out and put the flashed one in whenever they absolutely need to look at it. (unless it has a HAL moment or something I really can't see it needing to be flashed a lot)

 

BCMs are fairly inexpensive, right at $100, plus probably 1 hour labor to program it from the dealer.

 

Been thinking if "headlight" and "drl" are different pinouts on the bcm that means that when the headlights are in DRL mode they're using a different signal. So considering all the wiring is in there, yo could use a diode like spurshot did in the always on thread to make fogs come on with headlights, then just not use a foglight switch, since it serves no purpose at that point. You won't have control over when your fogs are on, but you can have them technically functional without all this nonsense.

 

Will look more when the trucks physically wired up and connected on that topic. if/when they dont come on when we push the switch, we'll have to dive into this as the 2nd phase of the project. Looks like those custom bcm deals can run as much as $300 or more. Seems a bit steep when diodes are what.. a dime each?

 

Another option is the old fashioned way. Graft a wire onto the switch, run it out through the firewall to a 12v relay that pulls from a running only hot source, then tie that in with a fuse to the main foglight harness and skip the truck harness entirely. That would cost a few bucks, wont look good, but is option C.

[GTPprix]

You can't swap bcm, lots of theft controls, the odometer etc.

[darkfox1]

Went down to a local dealer today and tried to get them to help me out. The salesman rolled his eyes as soon as I started talking and walked me back to the service department and basically dumped me there. Rude! Odd too. The last time I went to this dealer the sales people were very friendly. But of course at the time I was looking to buy. Not waste his precious lounging time chatting with the receptionist.

 

Luckily the service department fellas were another story. Real nice folks. They walked out to a truck and took a look under the hood, pulled the wiring diagram and the fuse panel diagram and confirmed that what I'm seeing is correct. Even on a factory fog light equipped truck there is no relay that is accessible. According to the techs the relay is more than likely PERMANENTLY ATTACHED to the fuse box housing. I asked what would happen if the relay failed. He said that the entire fuse panel would have to be replaced at a rather extreme cost. He agreed with me that this was kind of dumb on GM's part.

 

They also noted that the bcm was most likely not going to allow the fogs to work, and that the manufacturer would have to authorize a modification to said bcm.. something that they were unlikely to do.

 

I told him I had 3 plans. Plan A was to wire it up and see, plan B would be to see if a BCM modification would work. As soon as I mentioned a custom BCM programming he said he would not recommend this, as, if the dealer or the manufacturer found a custom program in the bcm they would blacklist the truck with a total vehicle warranty void.

 

I said plan C was to use the factory switch, but pull in my own wiring, basically like any old aftermarket lights. He said that would be fine and wouldn't bother the warranty, but to be careful where I pulled the 12v source, because the various control modules in the truck were very sensitive to voltage changes, and pulling from the wrong place may trigger a dash alarm. (like a turn signal bulb being out or something like that.)

 

I'm satisfied with the level of service these folks gave me, and frankly I'll probably go there for warranty work. They seem like a nice group of folks and they aren't packed crowded like the dealer I usually go to.

 

More than likely what we're looking at here is going to be plan C. I pull an ignition source 12v signal for the relay and I can run the fogs any time I like. Brights, low beams, drls, parking lamps.. they'll be independent.. and at a cost of a few bucks in the form of wires,a relay and an inline fuse (and various wire clamps, electrical tape, solder, heatshrink tubing, and some patience.) I'm ok with this.. it allows the fogs to be fully functional and imo would not severely detract from the resale value of the truck. If I can use the factory switch as well.. they will be totally integrated and unless there's a problem.. no average owner would be the wiser.

[blackout07]

 

I too am leaning toward plan c.

[GTPprix]

"if the dealer or the manufacturer found a custom program in the bcm they would blacklist the truck with a total vehicle warranty void." yeah, time to find another dealer. That's illegal under Magnuson moss lol our biggest customers are dealers! ;)

[darkfox1]

So for "plan C" which I like the most.. because well.. who cares what the bcm thinks right? if I want my fogs on I want em on! .... so long as they're only on with the ignition. I've been doing some thinking and some digging.

 

They say be careful for voltage fluctuations because the BCM is basically your truck's big brother. its always watching! Supposedly if it detects an anomaly it will shut the circuit down to protect it. This is apparently how the bcm knows that a turn signal bulb is out or something. I guess that means when you hit unlock on your keyfob its more than just a signal to you, its also checking its own circuits. I've been doing some reading on gm upfitter. I suggest it if you're interested. Lots of diagrams, pinouts, useful information!

 

Now I'm no electrician by ANY means. I can barely read a diagram, but I do understand the concept from my old car audio days when I was in college.

 

I want a relay that reads off the foglight momentary switch in the dash that becomes a latching relay, but only when accessory power is on.. AND it needs to be accessory power that wont freak the bcm out.

 

Here's my initial thoughts:

 

1. employ this guy. A parallax single relay board. Works up to 10a DC. (The factory fuse is 15a mind you..) pull the power for the relay from the cigarette lighters.. they're ignition based and door open based, and PROBABLY not as important to the bcm as components like the radio etc. The momentary switch of the factory fog light button connects to this, and the output runs under the hood to..

 

2. a standard automotive relay. This relay pulls its 12v from the battery through a 15a inline fuse. From there we run down to the fogs, and they ground to factory grounding points either in the chassis (under the radiator supports on each side) OR the factory grounding. At this point I'm almost abandoning my factory wiring entirely, so those $300 worth of wire harnesses I bought may be for nothing.

 

There may yet be a simpler way to do this that doesn't involve the cig lighter. I'm struggling to find something that is not drl, head, fog, turn, brake, radio but that is still accessory powered AND something that translates momentary switching into latching.

 

Total cost for my idea here should be what.. $30? and so long as you don't blow your cig lighter fuse your foglights will work.

 

If anyone has a better "accessory" point to latch on to I'm certainly willing to listen. I've been reading the LED lightbar thread for ideas but most of those folks are pulling an output from their foglight fuse.. whcih.. will not work thanks to the BCM gatekeeper.

 

btw Chris, I haven't gotten an email from you yet about the bcm reprogram. Did I get the right website? I dunno if my email made any sense.. I may have written it assuming that your crystal ball works. (my crystal ball has been broken for years.. but the people at work seem to not understand that. )

[TJay74]

Man I am telling you, the single most easiest way to do this is to send your BCM to Chris and have him flash it. That way it will work like the factory option. The only bad is if updates come out for the BCM for other issues/circuits you would need to weigh if the new update will be worth losing the fog lights option until you can send the BCM back to Chris.

 

As said the entire system (CANBUS) is very sensitive to voltage changes, if you are going to do this run a line directly from the battery fused to your switch on a relay with a 12v ignition source so that you don't accidently leave the lights on with the key off.

 

Sometimes the simplest way is the best one.