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Discussion Starter · #1 · (Edited)
Solved - F***ing computerized electrical crap - headlight switch / remote start

Tonight I decided to install footwell courtesy lights in my Avalanche since the brackets are there and my (base model) silverado had them and the newer, loaded-out avalanche did not. The installation went well, and I powered them off of an unused factory lighting circuit - right down to adding a pin to a factory harness. All I had left to do was secure the grounds for the light sockets. I left the truck for a couple of minutes to get a wrench with the door open and interior lights on, including the new footwell lights - everything worked fine. When I got back to the truck, the lights were off. Thinking the computer had just timed them out again to save the battery, I tried opening and closing a door to reactivate them, but to no avail.

At that point, I start to think that's a bit weird, so I try to start the truck. "Unknown Driver" appears in the DIC, and the truck shuts off as soon as it starts - as if Passlock is cutting power. My interior lights still don't work. Power door locks, windows, and right hand mirror don't work. seat memory doesn't work, but the power seats do. Radio doesn't work. Instrument cluster powers up but gauges don't work. Now I start to panic thinking my BCM somehow fried itself or died.

So, I came inside to do some research on the internet, being very concerned at this point. Nothing useful that I could find online or in GM service info other than to check for shorts.

Next step, go back out to the truck and check for any wires that might have shorted - I wiggle everything I touch and nothing changes. So I try the dimmer switch on the headlight switch and it doesnt work. Turn the switch from AUTO to the park light setting and the interior lights come on, windows and door locks work again, and the truck starts. Turn it back to auto with the truck running and the security light turns on. Then service 4WD, airbag, and ABS, and the DIC says "Unknown Driver". Switch it back to park lights, and everything works again but the security light stays on. When I turn the switch to park lights or on, everything works fine but if i don't have the interior lights overridden when I turn the switch back off after the truck is off, the interior lights will stay on but the other symptoms remain so my remote door locks wont work.

So, now for the summary: My headlight switch seems to have fried itself and because it is tied to the computer like everything else in the truck, it is causing communication issues between the BCM and other systems, which causes no radio, no gauges, service messages, and door modules not to work. I wont be able to get a new switch around here until monday so until then i guess i will just have to lock and unlock with the key and drive everywhere with my park lights or headlights on:grrrrrr:

I just hope that this post might be useful to someone else with a faulty headlight switch that causes strange symptoms. And who would have thought that a headlight switch could cause a no-start condition.

[/rant]
 

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I just don't understand it... I have added lights all over Both of my Avalanche's My old 02 and my 08. Never had a problem like that. People have added LED's and had some problems but most were simple to fix...Keep us updated.....
 

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Discussion Starter · #3 ·
I don't get it either. You would think that it should be perfectly fine to add factory lights in factory locations on factory circuits - and it was. I also had all sorts of lights and wiring on my '01 Silverado that connected different lighting circuits in a variety of ways and never had any problems with the factory wiring. This is ridiculous considering I never even touched the headlight switch last night. Based on the fact that my truck still works perfectly with the park lights or headlights on, I'm hoping this will be dealt with when I get a replacement switch tomorrow.
 

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Discussion Starter · #4 · (Edited)
:grrrrrr::grrrrrr::grrrrrr:NNNOOOOOOOOOOOOOOOOO!:grrrrrr::grrrrrr::grrrrrr:

I just got back from the auto wreckers where I bought, tried and returned a different headlight switch. The headlight switch didnt change anything. Sooo, this likely just became a GM dealer fix because apparently my BCM is broken and will only work if it senses the signal to turn the parking lights or headlights on from the switch - the automatic headlights dont have the same effect.

This could be expensive now. So, here is my new plan:

1) while I'm out trying to fix my Ford this afternoon (broken fuel pump on that one) I will try disconnecting the battery on the Avalanche for half an hour or so and see if it will maybe reset the BCM to work properly.
2) Failing that, I will have to put up with this irritating crap until the Ford runs again because I cant be without a vehicle to get to school.
3) If the avalanche doesn't sort itself out, I will have to take it to my local dealer for service. I've worked with the diagnostics guys there and they are top-notch, but thats at $139/ hour and the possibility of needing a whole new BCM.

Bottom line is that this is ridiculous and if the disconnecting the battery doesn't reset the BCM and fix this, this could be an expense that I REALLY don't need.
 

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Discussion Starter · #5 ·
Well, in one last-ditch effort to fix my truck before it went to the dealer, I decided to check all of my wiring under the dash one more time. This time I found a wire from my remote starter that had somehow been cut clean through. When I touched the 2 sides together, everything came back to life. I don't know how this remote start was wired in that it has become an essential and apparently non-removeable part of the truck, but reconnecting the 2 sides of the wire fixed the problem. It still seems strange to me though that turning the parking lights on seems to effectively activate the BCM in the same way.

Now, if I could just find my soldering iron I would go and fix that little bugger.
 

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Discussion Starter · #7 · (Edited)
It must have got caught on one of the wires I was running and sliced by some of the sharp metal brackets on the dashboard :neutral:

Another question that comes to mind is why the remote starter was installed as such an integral part of the truck. I've never seen an aftermarket remote starter that was wired in a way that it was integrated rather than add-on and couldn't be disconnected. Based on this, it seems that however this one was installed would make it so that if the remote starter was ever removed, the truck would have the same problem I just had.
 

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It must have got caught on one of the wires I was running and sliced by some of the sharp metal brackets on the dashboard :neutral:

Another question that comes to mind is why the remote starter was installed as such an integral part of the truck. I've never seen an aftermarket remote starter that was wired in a way that it was integrated rather than add-on and couldn't be disconnected. Based on this, it seems that however this one was installed would make it so that if the remote starter was ever removed, the truck would have the same problem I just had.
If your truck has Pass-Lock, the remote start would have to bypass that somehow to in order to activate the fuel pump and such, so perhaps it is tied into that system.
 

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Well, in one last-ditch effort to fix my truck before it went to the dealer, I decided to check all of my wiring under the dash one more time. This time I found a wire from my remote starter that had somehow been cut clean through. When I touched the 2 sides together, everything came back to life. I don't know how this remote start was wired in that it has become an essential and apparently non-removeable part of the truck, but reconnecting the 2 sides of the wire fixed the problem. It still seems strange to me though that turning the parking lights on seems to effectively activate the BCM in the same way.

Now, if I could just find my soldering iron I would go and fix that little bugger.

Hey man this is CRAZY i just had the same thing happen to my truck a few weeks ago! I started my day off as i usually do and went to my College classes and truck was running fine no signs of anything and then when i get back in it after i parked it it would turn on and motor wouldn't even try to turn over or anything after i left school and was done for the day at home! I have the Seriveice 4 wheel drive light, Service air bag,Service tire monitor system and also my radio want turn on but everything else on the truck works as far as lighting! I also have a aftermarket Python remote start and security system and have been told by my buddy the BCM is prob throwed off due to the auto start and everything and might be a wiring issue with it! I took the alternator and starter off and got them checked they are fine and run like new and my battery went dead also got it replaced and left it unhooked since the other one it just drained!!!! Also on the dash it has the Gold Lock as if it's locked for Anti Theft and the truck want do anything. I was told either wiring could throw the whole bcm off and it want start and the auto start could somehow throw a code that want let the truck fucntion!

I know for a fact the fuel pump is okay it primes you can hear it and the battery,alternator and starter are also fine. I checked my battery cables no corrosion on them at all and all Fuses are okay and not blown along with spark plugs are fine! I have checked everything i can and am pretty sure the ignition switch is fine also since there shouldn't be a problem with a truck with only 60k miles! I got the truck towed Friday For Free with USAA insurance thru the Military and will find out if it's the auto start monday since i told them to check the BCM and auto start for shorts and trouble codes!

I think if problem is resolved when my buddy installs my Recon Smoked cab roof lights and installs my headlight, tail light, third brake light and turn signals on tow mirrors smoked tint film i will be gettin the Python Auto Start and Security system taken off and will be selling on Ebay since i paid almost $800 for this!
 

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Im glad you got it sorted out to say the least, electrical crap does suck, its amazing how one wire can throw everything off
 

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Quick note. I have installed auto starts and security systems in hundreds of silverados and sierras, your model your requires the "interfacing" not bypassing, of the pass lock system which means you have to cut a gm wire, normally it's yellow, and tie a module inline with this wire (back in the day it would commonly be what's called a pass lock 3 module and it would have dipstick switches on it). What color wire was it that you reconnected that was apparently cut? A CORRECT auto start installation would had this yellow wire look like it was cut on accident to the untrained eye. Sometimes pass lock 3 modules just up and fail all of the sudden causing you to have to either replace the module to keep the auto start or reconnect this yellow wire (pass lock) and lose the functionality of the auto start. I wish GM were more like fords in this sense and would just use a transponder security system because you don't have to install "inline" to anything.

The installer of your auto start did it correctly, sounds to me like really bad timing.
 

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I had around the same thing happen to my truck i beleive it's the BCM and the Auto start causing the truck to go in Anti theft mode and it throwing a code and telling my truck not to start and throw other codes! My truck is at GM dealership will be looked at tomorrow and this week will find out what it is and i'm pretty sure it's the auto start i have since my buddy at GM dealership said the aftermarket systems end up failing for no reason. I prob. plan on taking mine off and selling it for around $400 since mine was really exspensive! Anyway i'll update on here when i find out exactly what i think it is!
 

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It's very common to have a stealership blame the auto start....very common, lithia chevy up here has blamed transmission failures on auto starts, it's a little out of control. I worked five years at Auto Trim Design of Alaska, they are DEI's biggest purchaser and installer of auto starts in the country. I can count on one hand how many times we have had the old pass lock and even the new PK+ modules fail causing a truck not to start... Even the crummy pass lock 3s are still pretty dang dependable. I would be hesitant to villainize the auto start...
 

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Okay if i have checked my alternator and took it off got it tested it's good along with my starter took it off got it tested it's good also. My battery ended up getting drained from whatever it is going on got a brand new one now it didn't help! The cables to the battery are fine no corrosion at all and my fuses are good none are blown at all. The only other things i could think of is the BCM because on my dash in my truck it has the gold lock as if it's Anti locked when it's not at all! I have looked online and everything and my buddy wouldn't lie to me about the Auto Start since many do have that problem depending how whom ever wired it. I don't just have a auto start i have the aftermarket security system with it also so it could also be short's in the wiring i assume.

The only other things i can think of is the ignition switch being bad other than that it has to be a electrical problem due to short's or the CPU or BCM messing up because it's throwing codes. The codes include service 4 wheel drive, serv. air bag and serv. tire monitor system. The other day before i got it towed for FREE from military insurance it tried to start more and just clicked and the radio came back on and worked and before it wouldn't and my stock remote to unlock doors didn't work and it worked but after that day everything stopped wrking again. Everything work's on my truck as far as lights and the Fuel pump even primes but i think other day it stopped didn't hear it or pay much attention. Idk what it is but i had to keep my battery unplugged because it was draining my battery! What's the problem you seem like you know!??
 

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So your battery keeps draining? How fast is it draining? You hit the nail on the head when you said "depends on who wired it". Referring to the pending fact that your auto start could be failing... The original poster's issue definitely sounds like the module for the auto start that interfaces with his pass lock security system has failed in an "open" position, which is indeed a rare way for them to fail, normally they fail "closed" so the auto start may stop working but the truck won't lock down.

Your situation DOES sound like hazardous wiring issues that could absolutely be coming from the auto start. What year is your rig? Because in trucks as old as the TBI gen. Your only tapping into a single wire on the truck for actual security sensing. The other equipment on the aftermarket security system is solely dependent on the auto start itself. 1990-1998 trucks and SUVs you solder to the dome sensing wire under the drive dash (you can select your desired polarity while prepping the auto start on the bench). On 1999-2007 you solder to a gray wire in the drivers side pillar which is a negative triggered dome sense wire which is why I doubt it is the security portion of your auto start causing the problem.

I do however believe you have something internal going on with your auto start board that is causing the problem and messy wiring with the possibility of two wires shorting together (I'm referring to the two pass lock wires in the ignition harness) are adding to a very frustrating scenario.

I doubt it's your ignition being bad but your harness, depending on the install quality of the auto start, could be compromised. Sounds like you have a competent friend at GM, he should be able to removed the auto start, reconnect the cut yellow pass lock wire and then hopefully your problem disappears.

Sorry if that's confusing, it's hard to articulate things on a forum for me, especially from my iPhone lol
 

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I have a 2008 chevy silverado z71 5.3 v8 and i agree it's something due to wiring because my truck had no signs of anything weird going on and that day i drove it and when i left my college and parked it and later was leaving i would turn the key and nothing would happen it wouldn't click or anything. I really havent checked my spark plugs but it's too late now and i doubt that's the problem also it has to be electrical. Hopefully tomorrow or day after they will call me and let me know what it is since i told them i have checked the major components in the engine bay and underneith and everything that is linked in to starting the truck.
 

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so your key should have a + on it right? Hmm that is odd I can't be anymore help for you because I have never experienced a NBS violate pass lock yet...they are very easy to install in and even easier to keep the wiring clean..... It's more common but still incredibly rare in the 1999-2007 OBS trucks and SUVs
 

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Idk what you mean when my key has a + on it?
 

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Discussion Starter · #20 · (Edited)
Quick note. I have installed auto starts and security systems in hundreds of silverados and sierras, your model your requires the "interfacing" not bypassing, of the pass lock system which means you have to cut a gm wire, normally it's yellow, and tie a module inline with this wire (back in the day it would commonly be what's called a pass lock 3 module and it would have dipstick switches on it). What color wire was it that you reconnected that was apparently cut? A CORRECT auto start installation would had this yellow wire look like it was cut on accident to the untrained eye. Sometimes pass lock 3 modules just up and fail all of the sudden causing you to have to either replace the module to keep the auto start or reconnect this yellow wire (pass lock) and lose the functionality of the auto start. I wish GM were more like fords in this sense and would just use a transponder security system because you don't have to install "inline" to anything.

The installer of your auto start did it correctly, sounds to me like really bad timing.
I'm going to jump back in here with what I know. I installed my own remote start on my last truck, so I am familiar with the PassLock 2 system gm used on the 1999-2007 trucks. I don't particularly care for it, but I know how it works. I also know that the interface module on this truck is a Fortin unit because it turns the heated seats on automatically when temperature is cold enough. I know that this type of interface is entirely computer based through the Class 2 Data system - one connection to the data wire from the OBD2 port, and that connection is present. I know that the issue I had was NOT a failure of any part of the remote start or interface system. The wire that was cut was not a factory wire... it was a heavier (18 gauge) black wire that was obviously not factory. I haven't taken the time to pull the knee bolster off and check out exactly how this system was wired in but the fact is that a Fortin system should NOT involve wiring anything inline with the truck, so that is why this is strange. My issue was fixed with reconnecting the wire, and it was NOT just a security issue. The PassLock was being activated which caused the no-start. BUT, the BCM seemed to be entirely shut down in that the radio, windows, door locks, driver mirror, interior lights, keyless entry, gauges, memory, etc. wouldn't work. The part I don't understand is how the remote starter caused this shutdown.

Idk what you mean when my key has a + on it?
The + on your key indicates that it is a key for vehicles with the PassKey 3 security system as opposed to the PassLock 2 system the 1999-2007 trucks had. The PassKey 3 uses a key with a transponder of sorts in it - your key has to be programmed to your vehicle. The PassLock 2 system I have is based on the ignition switch itself. The only security requirement is that the computer receives the correct signal from the ignition switch being physically turned... if a thief were to be able to pick it or turn it with a screwdriver they would be able to take it. (I also don't care for the PassLock 2 because there are only something like 9 different ignition switch programmings. Your system requires the correct key for the truck to start.
 
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