2002 Silverado...stuff staying on when I pull the key

bdoo · January 9, 2015

Hi, I'm Brad. I'm a new guy and am looking for a little help with my truck. Was just told by a garage I needed an expensive repair "somewhere" near my heat coil to get my heat back. I opted out. It was -15 without the wind yesterday. I used what I learned on here to burp the air out of it and voila...heats back. I'll still do a flush in the spring as I'm sure it needs it.

Anyway....got to work last night..turned the truck off and when the key came out the blower, dash lights, radio stayed on. Scared the crap out of me for a second like wtf did I just do? I am hoping its a relay or fuse or something and not the ignigion. I'm not well schooled on what's what as far as the electrics go. I am looking for a bit of guidance...if you don't mind.

Thanks, Brad

ifixedit · January 9, 2015

I'm wondering if the burping the air may have just been coincidence and the no heat and now the other odd things going on are pointing to another issue?

Could this be an issue with the BCM (body control module) which I believe controls these things that are acting up? I had a similar issue with all kinds of things acting up in my truck (interior lights, locks etc.) and it appeared some of the BCM connections had deteriorated and was the culprit. One day things were fine, the next not fine.

Not a hard project and worth a try before you start dumping money on it: First, disconnect the battery, the BCM is the box with several larger plugs and a multitude of wires going to it. It should be located directly under the dash on the drivers side pretty much right there under the steering column, if you can't find it or are not sure what it looks like, try google it's location on the internet, you should be able find it pretty easy. Disconnect each plug going to it, pack them with dielectric grease and reconnect them, hook up the battery and see what happens.

sahls01gmc · January 9, 2015

Great first place to start ifixedit! Start with the easy stuff first. Check all connections. Loose ground wires can cause havoc on everything.

Also, with you saying that the truck acted like you still had the key in, it's possible to check the tumbler as well. Maybe the tumbler has a loose connection, or is worn enough that it prevents good contact between each switch level.

Keep us posted on what you find! And welcome to the forum!

bdoo · January 9, 2015

Thank you for the replies. Here's what has transpired. When I got home his morning I disconnected BOTH battery cables to turn everything off. I reattached cables and started truck with radiator cap off to get some air out. I let the car run 15 minutes put the cap on , and let it run another 15 - 20 minutes with cap bqck on. All this time the heat was going fairly good. When I got the call to meet some buddies for lunch and a beer I turned the car off and everything went off.

So my guess is one of two things happened....disconecting the battery reset some relay or something.... or the new found heat unstuck something caused by it being -15 (-35) with wind chill. I do not have a garage.

I feel lucky ....like I got out of this cheap. However, is there some sort of basic preventative maint. you can do with relays and control boxes..ect to prevent future headaches? I know you mentioned dielectric grease?

ifixedit · January 9, 2015

If you haven't looked at the BCM yet, I would still check the connections to it as they after all this time could be a bit questionable, mine on my 03 were. Do the dielectric grease trick like I mention and see what happens, it certainly won't hurt anything. What drove me nuts before I figured out what was going on is one day all was fine and the next day things were acting weird. I discovered that changes in temperature and humidity along with the occasional bumpy road would bring on the problems. Since I've disconnected all the plugs to the BCM and gave them the dielectric grease treatment and reconnected, all has been good.

One thing I will say, at least by the experience with my 03, the GM plugs and connections do get questionable over time as I've had several issues with plugs seemingly well pushed in and connected and found them to be passing no or intermittent current, I had a similar issue with the tail lights as well, I'd have to bang on the damn things to get them to work, got stopped by a cop one day telling me my tail lights were out, they weren't, it was just the damn connection. Stuff just quits working like it should after 12 years and needs a little attention.

Dielectric grease is your friend!

gmtech4 · January 10, 2015

I think the key and cylinder are worn out causing the key to come out but leaving the ign switch in the " accessory " position ,

Nothing to do with the BCM , imo of course

bdoo · January 15, 2015

Sorry I haven't updated but been busy with other crap. So the problem with the lights blower and dash staying on with the key out is still happening. I took the key lock out and tried a different one. Didn't fix it. I guess its time to check the BCM but after looking through the trucks manual I saw nothing listed as a BCM. I'll do some googling but if anyone has more tips and ideas ...please feel free. I assume I have to take the dash off to get to it.

bdoo · January 15, 2015

Well I have had enough of this crap so I just went outside...took the bottom piece of dash off, and BAM , BCM and its 3 plugs staring me in the face. I carefully undid each plug, blew off any dust and firmly put it back into place. Voila....everything shut off when I turned the key off. First time in days. I'll head to the store tomorrow and get some dielectric grease and redo the plugs. Whole process took me 10 minutes. I'm such a pansy when it comes to messing with stuff because I'm afraid I'm gonna screw up something and have to pay for them to fix it. Thank you very much for pointing me in the right direction. You learn something new every day and today was a biggie.

sahls01gmc · January 15, 2015

Glad you figured it out!

ifixedit · January 15, 2015

Owning an 03 since day 1, now with 210,000 rounds on the clock, and witnessing all the weird things it's done, especially in the past few years now that it's getting into the "old timer" category, I have become convinced that these particular years of trucks have inherent problems with wiring and connections that only deteriorate and get worse over time. When you think about key switches, who here has had a single problem with one? I've owned many GM products dating back to a 1967 Chevelle and have NEVER had a worn out key switch no matter how used and abused the vehicle was. When it comes to these newer vehicles though, the wiring is woefully under sized, the plugs used are cheap, and it's all lucky to pass a solid signal even when new let alone old and has been subjected to dust, moisture, bumpy roads and general wear and tear. These poor connections also produce what some have referred to as "static noise" in the system and when one component connected to the same power source is acting up, I don't care if the thing on the other end is related and in the same circuit or not, if it's connected to the same power source it can wreak havoc and all kinds of weird things can happen. Turns out my BCM's lack of a good connection was causing severe problems with throttle bodies for me, seemingly of no relationship to each other but connected to the same power source, so again one bad thing causes other issue. I also recently discovered an issue the the power seat on the drivers side, if I move the seat it has caused my truck to go into Reduced Power Mode, same goes for a shorted out fan switch I recently replaced. Go figure!! I just know what to look for now.

In any case glad this seems to be the fix for you and I hope has solved it once and for all.

bdoo · January 15, 2015

I just can't win. Just ran some errands and when I got home...its right back to it...stuff not turning off. Seems the only time it appears fixed is after I disconnect BOTH battery cables for a brief period of time. Then the problem comes back. Its really getting old, and frustrating, to have to pop the hood and undo the cables to shut my truck off.

gmtech4 · January 16, 2015

I just can't win. Just ran some errands and when I got home...its right back to it...stuff not turning off. Seems the only time it appears fixed is after I disconnect BOTH battery cables for a brief period of time. Then the problem comes back. Its really getting old, and frustrating, to have to pop the hood and undo the cables to shut my truck off.

Get the BCM scanned