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Discussion Starter #1
My wife took her cobalt to the store earlier this morning and as she was puling into the parking lot the engine died and the dash said "engine disabled" and wouldn't start. I got there, hit the key and it fired right up but the check engine light was on. I put my code scanner on it and it only showed 1 code and that was P0601. I cleared the code and drove it home with no issues what so ever. I looked up the code once i got home and according to what I've seen the P0601 means either the PCM is bad or a voltage issue and or ground issue. Can anyone give me advice on how to check the voltage and ground, more specifically what pins on the PCM these checks should be made at? For now I'm going to let the engine cool down and drive it again to see if it does it again. Any help would be appreciated.
 

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Discussion Starter #2
I took the cobalt to work this morning, it started up fine but seemed to struggle a bit as I was pulling out of the driveway but it stayed running. It's actually done that before on occasion but no check engine light has ever come on or trouble codes. Where I work is about a 40 mile round trip, when I got there I asked for a vacation day while all the time I kept the car running. When I got home I plugged my reader into it, of course no trouble codes but there are 7 system readiness checks the PCM does, 3 of which can only be completed after a drive cycle. I figured that 40 mile drive to work and back would've been plenty of time for the PCM to complete all those readiness checks however only 6 were completed except for the evap system check. Basically what I'm trying to do is rule out any possibilities before replacing the PCM. I have limited experience with automotive electronics but what I do know is that 50% of the time when someone thinks the PCM is bad, it turns out the old one was just fine and the problem was else where. The last time a PCM went bad on me on another car, the PCM was showing a whole list of codes. in this case though it's only showed the P0601 code which doesn't give me much to go on other than the PCM is actually failing.
 

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As far as I can tell the P0601 code means either the PCM is bad or or it's not getting enough voltage. The battery is fine but have yet to determine what pin on the PCM connectors to check to confirm that and I'm not going to guess at it. I have talked to a Chevy mechanic a few minutes ago and he said that so far every time he's seen the P0601 code, especially if that's the only error code, he ends up replacing the PCM. I'll be ordering another PCM and I'll update to let you all know how it worked out.
 
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