2008 suburban LTZ will not start

[ejstave]

I have a 2008 suburban ltz. It has been in my garage for a couple days and now the key fobs, dome lights, backup lights etc. are not working. When I put the key in the ignition, it will not crank. There is not a security light that stays on or flashes... I also cannot open the rear hatch, or wind down the windows. Very strange. Any idea what it could be?

[ejstave]

Dann... I'd post a pic of I could figure it out off my phone. Mine are all dead just 3 lights.

 

Scantool pulls no codes...

[ejstave]

I can get a salvage BCM for $50. I wonder if it will fire with that installed?

[Duelin]

A different BCM will have to be programed to your vehicle. And what did you you find out with the voltage drop test? I think you are loosing voltage from the battery. You are going to have to start tracing it back starting at the battery and working your way back.

[ejstave]

12.5-12.6v @ the fuse for the BCM... with the charger connected I get 13.4 at the fuse. not sure where to go from here. Cant crank it with the key. Might have to push it out of the garage and have it towed in.

[Duelin]

When you are diagnosing you can't just check the battery and then bypass everything else and jump to the BCM fuse. You have to start at the battery and work you way back thru the system. For example do you have power going to the starter? Are you getting power to the ignition switch? if so are you getting power coming out of the ignition switch. Do you have power to the starter relay? Is the starter relay being activated and nothing happens. Now this is a few of the steps that should be done before you jump in and start buying and changing computers. That thought process can create more problems than you already have. Anyway have you check your starter fuse? It should be a 40 Amp fuse.

[Jsdirt]

^^^ This will save you money in the long run - find out exactly what the issue is before just shotgunning parts at it. You'll be much happier.

[Duelin]

When you tested the battery did you do a load test or just a voltage test? The first thing I would do is a load test. Then I would start with a voltage drop test. And then I would proceed from there.

[Doug_Scott]

Remember there are two connections on every wire. Take a good look at the other ends of the battery cables, paying particular attention to the ground cable. Look closely at the crimp for any sign of corrosion. In the first stages of diagnosing this, forget about the computer part of it, and pay attention to the very basic systems. This is no different to diagnosing a no crank issue on a non computerized vehicle.

[ejstave]

I can jump the starter relay and it cranks just fine. I checked the grounds and the positive leads and found nothing strange.

[ejstave]

I just noticed that the radio says theftlocked. But I get no security light on the dash...

[Jsdirt]

I'd bet your battery is stone dead. This has happened to my '07 Silverado 3 times so far without explanation. Good batteries too - just developed a rogue current draw in it's sleep, and sucked the battery dry.

 

Electronics for ya ...

[ejstave]

Just tested the battery. 100% charged. I am wondering if its the BCM.

[Jsdirt]

That's a possibility too. Since the battery is good, sounds like that's probably the next thing to check out.

[ejstave]

Wish I knew how to tell if it's bad!

[Jsdirt]

Here's an entertaining video of some of the problems it will cause. One commenter says, " The power of Ford compels you! " HAHAHA!

 

Scan tool should be able to pull codes out of it. That will at least give a sliver of direction.

 

Here's a thread about a HHR with BCM issues: http://www.chevyhhr.net/forums/problems-service-repairs-42/what-all-does-bcm-control-what-symptoms-bad-one-39513/