David Adams

Hello everyone, I'll try to make this short. Basically I swapped the engine in my 2008 Cobalt LS 2.2. Well then I had to replace the ECM as it just died all of a sudden. Then I was unable to take they key out without pressing the interlock button. Then in the same day I was unable to even shut the car off. I schedule the recall and basically they call and say they cannot get the car to crank anymore. They pass blame saying the fusebox has water damage and was unscrewed (yes it was). Now the car does nothing. No CEL when I try to start. No tell tale lights except for the security light. No brake or seat belt light. Odometer works and flashes low fuel, airbag and power steering. Very similar to when the ECU died but the no lights tell me there's more. Also there's no power to the ECM/TRANS fuse. The technician says fuse box but how can I be sure? Thanks for any help.

BKRedline

Battery good?

David Adams

Got 12 volts.

Snail_SS

iTrader: (3)

12 volts would mean it's dead

jdbaugh1

iTrader: (1)

I had these exact same symptoms when I got my car pieced back together after rebuild. I had my IP IGN fuse off a slot in the fuse box. Check your IP IGN fuse and make sure it has good connection and power. There may also be a relay to check but my problem was at the fuse. I would say they are correct in their diagnosis. If the IGN fuse or relay(s) are good and their connections look good then I would pop the top of the box back off and visually inspect for corrosion, bent pens, or anything out of the ordinary.

David Adams

Sorry everyone. Was driving home all day from the eclipse. As a side note what a fantastic event.

To snail; the battery was hooked up to my booster and definitely was fully charged. I was getting the same voltage at the jump post on the fuse block.

To jdbaugh; if I recall the IP IGN was getting no power. I took the car to them with the connector bolts backed out but still making good contact (or it would not have ran). The technician said he tightened them down which he did, but I'm not sure if that was before or after he couldn't get it to crank. I do think the IP IGN fuse wasn't blown but again this is from 3 day old memory. I'll check tomorrow. What other fuses should I check? I'm having the car dropped off tomorrow at the reputable indy and I told him what the diagnosis was from Chevy (or where they wanted to start anyway). Is there anyway to test the fuse block itself? I know that with it being water damaged that some circuits will be complete and normal and others will not. It looks like no modules are getting any power at this point. Thanks for the help and I'll give you an update on the fuses tomorrow.

jdbaugh1

iTrader: (1)

I would pop the top off of the fuse bock again and visually inspect the conductive surfaces. I would think the only way water would screw it up is corrosion deposits as it isn't really like a sensitive circuit board. Also check for bent prongs or anything that looks out of the ordinary. You need power at the IP IGN fuse or this is all it will do. I'm sure there is some IGN relays that you should check as well. With what you have told me about not having power there I really think your problem is in that fuse box but you won't track it down without at least a test light and figuring out where you aren't getting connection. First thing, if you removed and relays or fuses, is to look at the layout on the back of the lid and make sure everything is put back exactly where it is supposed to be. The 4 prong relays can be installed backwards so check that as well.

David Adams

Ok. The battery is currently dead and so is my booster. I'll get a battery charger tomorrow and my booster charged and test if there is power at the IP IGN fuse. I do have a test light but would a DVMM be acceptable to use? And am I testing for 12VDC? I'll also test the fuses on the back side for the BCM and the large 50 amp fuse in the trunk. I did check all of them visually and they weren't blown. JD; I know you keep saying it's likely the fuse block which is good as it's not very expensive and easy to chang, but what fuses should be getting power that I can check? Whats the lilelihood you believe that its bad? And would it be better to test for voltage at the sockets or on the exposed leads of the fuse? Thanks so much for your help so far. If you reply tonight I'll read it but probably won't be able to reply until tomorrow with results. Thanks!

jdbaugh1

iTrader: (1)

Well first make sure you have power. Sounds like that could have been your problem? If the lights on the dash don't all light up like normal THEN I would think it may be your fuse box. Really best would be to put a good battery in it and take a video of you trying to start. I just know when you try to turn on the car and the only light is the security light to check the IP IGN fuse because it happened to me. It's also a location with a lot of connections. I'm sure you've visually checked your wires.

David Adams

It definitely was getting power. The crank fuse and constant hot at the relay were enough to get the test light to shine bright and also had the same values as when the car was running. JD, I'll get a video of the dash lights tomorrow for ya on the YouTube. I'll also check for power at the IP IGN fuse. In the mean time are there any circuits that I can ohm tonight to test for resistance or opens? I'll get a battery tomorrow and upload the video shortly after I get It installed.

jdbaugh1

iTrader: (1)

Need to see how it is acting before making any guesses. Need to see what is coming on and what isn't.

David Adams

Well, an update. The Indy shop came and picked up the car today. Unfortunately I wasn't able to get a video of the dash. However like I said the only telltale light was the security light. The gauges still light up and so do the odometer. I actually completely forgot to get a video. However I should have some kind of update Monday as they'll be looking at it then.

David Adams

Alright, so an update, kind of. Still the same thing. I still haven't been able to get a video. However the shop thinks that they may have hooked up the ignition switch incorrectly, causing the BCM not to know what position the key is in. Also he wants the original computer but I've already given it away as a core. He thinks the replacement computer and new switch aren't communicating. Does that sound right? Recall I did replace the ECM because the original one died. Any thoughts?

David Adams

Tomorrow, he will be looking at a few items. The #8 fuse in the passenger kick panel, and the switch itself. My logic is this: the technician may have in fact installed the switch improperly. Why? Well from my limited knowledge, the switch is actually just a sensor, basically. It tells the BCM "hey, I'm in run/start/ACC/off". So if the switch isn't sending a signal to the BCM at all, then the telltale lights won't come on (CEL, brake, seat belt, etc). However what bewilders me is Why does the gauges come on? The odometer, the warning center, and gauge back lights all light up. I thought these were all controlled by the BCM. Any input? Also the only tell tale light that does illuminate is the security light still. I'll also tell him to check for power at IP IGN as well.