I am stumped...After key is off, engine continues to runs and diesels, dash goes arry (check engine light blinks on off along with security light), and door locks unlock, lock, unlock. I have searched and searched and found nothing... does anybody know what it might be???? I have an 2006 Cobalt SS

 

Any electrical work done recently?

Off hand, sounds like a bad ignition switch not shutting down fully, but i'd lean towards a fuse box issue.

 

Does it shut off after a few seconds?

 

I'm lost as to what "run a diesels" means

 

^ that

 

me too.

 

Dieseling is when a gas engine continues to run after the ignition has been turned off. Usually there is a hot spot in the cylinder or carbon build up that holds enough heat to cause ignition when combined with the compression occurring within the cylinder. Hence it "diesels"

Incorrect timing, incorrect plugs, carbon build-up, all can cause this.

 

 

I think he meant run away diesel. This happens cause the fuel cut off doesn't happen and since they work off compression and not an electrical spark you can what is called a run away diesel and you can either cut the air coming in, the fuel, or just let it run out of diesel.

 

what is your temperature your dash say you?? high temperature can cause this see your radiator blower if he start

 

Oh I've never heard of that. You learn something new everyday.

 

only difference is when a diesel runs out of fuel. BOOM

 

By diesel I mean it sputters, doesn't shut off, it clugs. But the temps are fine, nothing new electrical wise, last thing I did was put new headlights in about 2 weeks before this happened. I checked grounds. Does the PCM maybe need more of a ground? It literally just started happening, no warning or anything. Cleaned filter and MAF thinking it may be that.

 

Unplug the coil packs while it's "Deilsing" and if it stops runnig, it wasn't truly diesling...

 

I know this sounds very strange but if you unplug your cooling fan and then shut your engine off it will shut off like normal. Try it, it is a simple fix before you go tearing things apart.

 

The dieselimg is just a symptom of another problem ,his lock are opening and closing at the same time which point to a electrical problem .
If it happens all the time ,next time you pull in the drive way open up the hood shut the car off and when it start dieseling tap on the crank run relay if it stops I would think the relay is bad.when it doesn't stop pull the relay.if it stops try replacing it but could be ignition switch related as well.
You could also try banging on the other relays.
Check PCM connections as well.
And bcm connections.(I'm leaning towards something with this either directly or indirectly since the locks are cycling as well)

Your fuse box under the hood isn't damp inside if so take the hair dryer to it or let the sun dry it out.

 

I have never heard of it happening on a fuel injected car, used to be a very common problem with carbed engines. I know the phenomenon well because I have a 74 Trans-am that used to do it all the time. In my case the carb just needed a rebuild to get rid of it.

 

I've seen cases of the BCM coming loose and touching against stuff and shorting/grouding, check under the console on the passenger side, it should be secured and not loose, and there should be no exposed wires or anything. It was giving the same lock/unlock stuff.

 

Only thing I can find on it from GM is check the PCM ground or Grounds.
and leaking Injectors.
But Im still leaning towards something to do with the BCM.

 

Well... From the beginning I thought it may be the ignition switch... The shop confirmed it today, good thing I bought the extended warranty, $55 part, I pay the tax, sooo... $5... good day!

 

Cars been in shop for a week now.... replaced bcm, and ig switch... still having the same damn problem...

 

Hey, What did the issue end up being?

 

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