I'm keen on electrical things, so I've dig through these schematics:
Wiring Diagram: 2000 chevy blazer wiring diagram Chevy Blazer Trailer Wiring Diagram, 2000 Chevy Blazer Transmission Diagram, 2000 Blazer Fuel Pump Wiring ~ Easyhomeview.Com
Diagram 4. It looks like the ignition switch should kill the power to ECM.
On that diagram, the backup lights have a switch, so I am confused - why can't You kill them with a switch...? Also, the gauge fuse appears to have a rating of 20amps...

 

I pulled the fuse box today. I didn't find anything with the wires in the engine bay.


I found the light green wire in the red connector's harness. So I followed that and pulled it down through and out the bottom of the car and found this.


Pulled the heat wrap and split loom off, and look which wire was damaged. However, it doesn't appear to have gone through the insulation.


I had to call it quits because it started raining. So I tucked the wiring back under the car and cleaned up the tools. My plan is to cut the burn pieces out, repair it and put it back together to see what happens. It is supposed to rain again tomorrow I am not sure if I'll get to it.

 

Congratulations If it does not help You with the problem You have now - it may save You the others in a future. Kindly asking You to update the topic with a photo showing the location. Seems the wrap and loom are prone for tearing there - so I'd check how is mine.

 

I am not exactly sure where it burnt because I didn't see it until I pulled it out. I will see if I can pinpoint it today if the rain holds off. I also need to finds some more heat tape.

 

I fixed the wires and put everything back together between rain showers today.


As soon as I hooked up the battery the backup lights came on. I pulled every fuse in the dash and they were still on. Also, the rear hatch glass still randomly pops open. I started the car and my security light stayed on and the gauges took about 30 seconds to come on. I turned the headlights on and it took them several seconds to turn back off. The engine doesn't stay on now, it starts and turns off fine with the key. So basically I fixed one thing and found 2 new problems. I guess this week I will pull the harness further back from where I had taken it out too look for more damaged wires.

 

Am I correct that this all started when you sprayed PB blast in the door mechanism? There is a circuit for the door actuator there. Maybe created a short that freaked out your BCM? Might want to pull the door panel off and have a look. Maybe even disconnect that plug and check the power and ground.

 

Tajohns, I was looking at the pin outs for my BCM and noticed the passenger door jamb pin out was right next to the lift glass release switch and that triggered a memory. I watched a video awhile ago where a guy was working on a car that was completely whacko. All kinds of strange crap happening at once. It ended up being a broken ground wire in the rubber boot in between the door and the car body. Nothing the car was doing would have made it obvious. It had interior problems, chime problems, ignition problems all kinds of crap. I wonder if that door latch issue was a first symptom. I'd pull that door panel off, peel back the boot, and drop the glove box door and take a good look at the wiring that goes from the door into the cab.


EDIT: In the case I'm talking about it was a broken ground wire in the driver's door boot, so you might want to check that also.

 

 

Hey George,
Under normal circumstances I agree with the source of power. However, as in the example of the video I explained, that one broken ground wire thru everything into a tizzy. Things were getting power when they should not have.

The BCM gets B(+) from the Body Bussed Electrical Center (via the TBC fuse in the UBEC) tucked up under the dash behind I/P Fuse Panel. I think the reason he will have lights and other things change their state after a few minutes is due to the relays in the BBEC. I'm thinking of the possibility that the lights will stay on all night because the RAP relay is not opening, which could be why pulling fuses is not shutting the lights off. Even though that doesn't seem to make sense, if the loss of a ground is causing power for another circuit to find another path that could make things whacky as in the video. There are many splice packs and other paths through the BCM, the ignition switch, etc.

Another thing I would check is the polarity of the backup lamp plug. It is possible that power is actually coming through the normally ground side of the socket and has found a ground through the normally power side. As you know the lamps don't care which side power comes from.

I'm not certain of any of these things without being there myself with a test light and a meter, but I would go simple first. Go to Autozone, they have a loaner tool called an "Amp Hound". Very simple to use. If you lived a little bit closer, I'd let you borrow mine. Leave everything connected. Except your underhood light. Disconnect that. Wait 20 minutes for the retained power to "normally" cut off. Then working at the UBEC touch the the back each fuse with the two probes and record which fuses have current going thru them and how much amperage. The instructions are in the kit. It's really simple, and fast. Since I'm assuming your backup lamps will be on while you're waiting the 20 minutes, you might want to insure you have a fully charged battery. Make sure you don't open any doors or do anything else to "wake up" the truck.

 

I've been following a while now.
What makes me wonder if somebody has been tinkering with the wiring before.

It sounds as it comes down to check all wiring.
If the backup lights are on all the time if should be possible to figure from connector to connector backwards or forward where that current comes from.