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LS Engine Specialist.
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1,193 Posts
Discussion Starter #1 (Edited)
OK guys, well here's something I've never ran into before.

Yesterday, I went out to my car, got in it, and drove it to my local O'Reilly's. Got there, got out, and didn't even lock the car, later I finished up inside, walked out to my car, loaded everything in the back seat and then I hopped in. Stuck the key in the ignition, fired her up and the dash did a few funky things like got stuck between displaying Security Check and MPH, but then it went to the full digital MPH display (this is all happening within a few seconds.)

Here's where it gets really weird though, I put the car in reverse, and it locked each door one at a time starting with the drivers door and ending with the Passenger right rear door. Starting to get scared that it might self destruct or something, I backed up a few feet, and it rolled both front windows down by itself, and killed the engine dead.

Now the car's gauges were stuck at their current values, like 2 mph, and 800rpm. So I tried to turn the key off, and it refused to let go past ACC mode, turned it back to on and then it was dead. Flashed this message across the Radio Display. "Security Lockout Active/Vehicle Data Mismatching" WHAT??? I've been using only one key since I've had the car as that's the only one there was.

I checked all the fuses in the car. They all seem to be good, the battery has a solid 12.5volts, and it's basically brand new. The only dumbshiit thing I've done is used the key with a dead battery in it for the past 2 weeks. (Manually locking and unlocking the car, etc.)

Uh so does anyone have any clue where to start? I can't even access the ECM right now to disable the VATS with my HPTuners. Nor can I make a call to Onstar from in the car. I mean it is locked down tight. It basically thinks I tried to steal it. Not to mention my car is so far away from stock I don't think a GM dealer in the country will touch it. What do you guys think?

Thanks all,
-Robbie.
 

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LS Engine Specialist.
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1,193 Posts
Discussion Starter #2 (Edited)
yours sounds more like you lost all the power under the hood. The power goes from the jumper post in the engine bay, down to the alternator, then up to the relay box at the right front location. Other than a direct power wire going to power up the starter motor, all the circuits are protected by an inline 175a fuse link in the wire going from the post to the alternator. That wire looks like its in an area where any modified exhaust tubing might be able to contact that wire (burn or short out). If you have 12 volts at the post, but zero volts at the underhood fuse block, that would indicate to me that you would have to ts the wiring between those 2 locations. Bad situation you have here for sure. No matter what happened.
-gopherit I will check the undercar wiring ASAP and see if there's power at the fuse block. Thank you.
 

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Premium Member
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4,137 Posts
I have no idea what the symptoms would be like, if the F12--2A ( labeled DLIS/THEFT DTRNT ) an located in the I/P fuse panel, opened up when the car is already running, in gear etc. But for sure it would shut down the engine. As tricky as this "theft deterrent" circuit is, maybe it is commanded to do all those things that your car did, when in motion. Maybe even kill the accessory bus, trapping your key in the ignition, along with the other stuff.
 

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LS Engine Specialist.
Joined
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1,193 Posts
Discussion Starter #4
I have no idea what the symptoms would be like, if the F12--2A ( labeled DLIS/THEFT DTRNT ) an located in the I/P fuse panel, opened up when the car is already running, in gear etc. But for sure it would shut down the engine. As tricky as this "theft deterrent" circuit is, maybe it is commanded to do all those things that your car did, when in motion. Maybe even kill the accessory bus, trapping your key in the ignition, along with the other stuff.
Perhaps. By the way I checked the full body wiring and found nothing out of the ordinary, also the main fuse block under the hood is showing good voltage, along with the terminal connector.

Maybe it just randomly fried the BCM? According to General Motors, the G8 is the only car in the Pontiac lineup that this is a known problem for. :/
 

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'Mod'erator
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4,887 Posts
dude that really sucks. I don't know what to say besides take it to a dealer. Someone will look at it. It will just cost you.
 

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Premium Member
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4,137 Posts
IDRIVEAG8GT--- Like you say, the PMM (power mode master) in our cars is the BCM. Short of smoking itself, it does look to be "self protected" pretty good. Something like, if it senses something is shorted out, it disables drivers within itself for self protection. This would cause other modules to revert to a default mode of operation, an so on, an so on. There should be unique fault codes that will set, when something like this happens ( like B1440 00 ) But how to read them with a code reader, if your car is currently totally dead to the point of being unable to get power to the DLC !! . If it turns out to be a smoked BCM, an was caused by an exterior problem, how do you find it, to keep it from wiping out a new unit, etc. The problem *you* have, is even painful to me, just knowing about it.
 

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out front & pulling away
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208 Posts
Very sad to say. The OP took his life some years ago.
 
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