My son has a 2010 Cobalt LT 2.2 ecotec. He came over and told me it had been sputtering. He had the codes bread and had a P0223 code. So we disconnected the negative from the battery and checked the TB. Seemed alright, clean and in the correct position. So hooked the battery back up and the engine reduce pwr began to display and wouldn't start. Turned over just fine but not start. So I got my odb and received P0223, P0122, P0010, P0107, P0013, P0443, P0973. All circuit high or low codes... assuming a short or faulty ground checked and cleaned engine block ground. Others looked read fine on my multi meter. Pulled negative cable once again and attached a probe light between terminal and post. It illuminated. Pulled fuses starting inside moving to under hood until it went off on the BCM 2 40amp(under hood box). Should we replace the BCM? If so does a new one have to be flashed? Will a junkyard one work? And do p/n have to be exact?

 

I don't know if you should replace it or not - they've been slightly problematic on these cars; usually due to terrible grounds. BUT if you replace it, the part number of the BCM absolutely has to be the same and it will have to be reprogrammed by the dealer (I'm not positive that ANYONE with a TechII can do it, but maybe?).

Maybe this will help, maybe not.

https://www.cobaltss.net/forums/2-0l...essage-247349/

 

I found three grounds the one on the back top side of engine did have resistance so clean and it's good now. The other two were on the strut tower and just above the head light. Is there another I should look for? And would a faulty ground cause power to feed back down the negative all the way to the battery?

 

There's another on the front side of the engine, right above the starter and on the starter... it's where the headlight one runs. I think the BCM has its own grounds inside the cabin... but I haven't investigated completely.

I'm not 100% sure you have a BCM issue though. Connecting a tester light from ground cable to negative battery terminal should illuminate - you're completing the circuit (unless I'm not understanding your procedure correctly).

As far as the fuse lighting up, I don't know - haven't tested mine. The BCM controls a lot of things though, so I wouldn't be surprised to find out it was active, even when the car was not. Security system and keyless entry all run through it.

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Re-reading your first post... you might just have a busted throttle body - they tend to throw a handful of codes at once, some not even for items related to the throttle body. High/Low Circuits, Correlation codes, etc. Or when you unplugged it to check it, you didn't fully plug it back in. Try unplugging it and then replugging it. Try to make sure you get a click.

When you had the throttle body off, did you move the butterfly with your fingers much? The TPS on these cars is inside the throttle body and has been known to be sensitive and easy to break when trying to clean a throttle body.

 

I know the throttle is plugged back in correctly but what a broken TPS cause the reduced engine power display and the no start?
He also had issues with door lock locking and un lock by itself until fuse was pulled as well as intermittent window switches not working. And to explain better when connected to the negative battery post and the negative cable the probe lights up... this is normal?

 

It's worth checking the plug - it seems simple, but the TB plug/connection isn't great. I've had times when I thought it was on all the way, but it wasn't.

And a broken throttle body will definitely put the car in reduced engine power (Limp) mode. The no start might be related; no idea. Mine would always enter limp mode while I was driving it - if I let off the throttle too suddenly, but that's just my experience.

 

Plug is in and ground was good but cleaned anyways. Something I have been seeing is about leaving the key in the ignition... the tip of his key broke off and is in the cylinder. Could this have anything to do with the sudden appearance of the engine pwr reduced? Plan to get a TB assembly from junk yard tomorrow ( it's off an 09 running). Also attempted to clear codes and wouldn't clear... possibly due to my cheap hyper tough obd II.

 

Ok so replaced the TB and no change. Still engine reduced and no start.

 

It is normal the a test light would light up if you disconnect the negative cable and probe it and the battery post. What you want to test is the negative post (with the cable hooked up) compared to the chassis. If that lights up then you know you have severe ground problem.

 

I don't think the BCM would cause these codes, they seem to be on the ECM side of control. You may want to check the underhood fuse box connectors for corrosion, you will have to remove the fuse box to do so but it's not too difficult. It also wouldn't hurt to check the connectors on the ECM for bent pins or corrosion. On the ECM connector I had a pin for the starter circuit bend very slightly (almost unnoticeable) and it led to the "engine pwr reduced" and eventually "engine disabled".