ECM-PCM Change

Tiny
M0RDECAI89
  • 2006 CHEVROLET COBALT

Computer problem 4 cyl Front Wheel Drive Automatic 40000 miles

Hi my old ECM was bad and the dealer wanted 600 dollars for a new one. I decided not to pay this and instead found one on my own at a salvage yard. My question is when I put the new ECM in my car do I have to take it to the dealer to reset it or something so it will work with my car, or can I just plug it in and go. I called the dealership and they said they had to reset it to work with my car, but they are the liars that ruined it in the first place and sold me a bad car so I am looking for a neutral party to answer. Thanks in advance. How would I go about flash reprogramming myself. I am also open to going to a mechanic if they can do it. I called the dealership and they wanted almost 300 to reflash it so that really isn't an option. But as I said how can I do it or can a non GM mechanic do it?

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Monday, February 9th, 2009 AT 10:57 PM

17 Replies

Tiny
2CARPROS KEN
  • ADMIN
  • 12,124 POSTS

Hello,

Back in the day you used to be able to plug and play a PCM but nowdays there are many computers on the network communicating through the CAN (computer area network).

You can get a used unit and have a shop reprogram it for you for about $140.00. Bring the old computer with you.

Use the retaining tab to secure the ECM, when installing the ECM to the underhood junction block bracket. NOTE: Control module damage may result when the metal case contacts battery voltage. DO NOT contact the control module metal case with battery voltage when servicing a control module, using battery booster cables or when charging the vehicle's battery.

Here is the location of the PCM (Below)

Please let us know if you need anything else to get the problem fixed.

Cheers, Ken

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Thursday, November 16th, 2017 AT 3:08 PM
Tiny
NEKA72705
  • 2006 CHEVROLET COBALT
  • 100,000 MILES

At one point in time my car would cut off when coming around the corner or reversing, not every time. Although it would crank right back up. I took my car to my mechanic and there was no oil in the engine. He at it or you instructed me to crank up the car. The car would not start I know my battery was weak so we attempted to jump it. Nothing. After a day or so of looking at my car he told me I need a new computer. After installing the new computer, the computer programming technician and and for my mechanic that my engine was not receiving any compression. After getting a new mechanic who replaced the engine, the fuse box & the ignition coil we now must program the computer. But my mechanic believe that my computer was never replaceD. My question to you all is that can the car start and drive without the computer being programed? Because I am getting completeness scenarios. Please help.

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Thursday, November 16th, 2017 AT 3:09 PM (Merged)
Tiny
HMAC300
  • EXPERT
  • 49,757 POSTS

No the pcm needs to be programmed but if it hasn't been replaced try starting it if it wont' start try resetting your anti theft ehn try again. Or h ave it scanned for codes that should tell you if it's been replaced or not. 2 things to advise, check oil every other fill up and find a better mechanic or the one you have

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Thursday, November 16th, 2017 AT 3:09 PM (Merged)
Tiny
M0RDECAI89
  • 2006 CHEVROLET COBALT

Computer problem
2006 Chevy Cobalt 4 cyl Front Wheel Drive Automatic 38000 miles

Hey I have a 2006 Chevy Cobalt with 38xxx miles on it. A couple months ago GM called and said there was an ECM reprogram campaign. Thinking it was neccessary I took it in and had this done. After I did this I began to noticce changes in the cars performance and fuel consumption. Prior to the reprogram I was very satisfied with the power and response from my little car, after wards the transmission will not shift at times and the engine is often unresponsive or late to my pedal commands. ALso my gas mileage went from 32 mpg to 26 mpg after the reprogram which is suspicious because that is when the new EPA estimates came out for gas mileage. Is there anyway I can reset my ECM to the original factory settings and undo the reprogram or should I buy a new ECM.

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Thursday, November 16th, 2017 AT 3:10 PM (Merged)
Tiny
JDL
  • EXPERT
  • 16,334 POSTS

Hi, did you talk to the dealership about your problems? What did they have to say?

Even if you buy a new computer, it may have this update already installed. It may not make any difference?

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Thursday, November 16th, 2017 AT 3:10 PM (Merged)
Tiny
M0RDECAI89
  • MEMBER

The dealership insisted this was not true and that the reprogram was correct. They also wanted 100 dollars just to look at it. So there is no way for me to reset the ECM to factory settings? Can the dealership restore original settings?

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Thursday, November 16th, 2017 AT 3:10 PM (Merged)
Tiny
JDL
  • EXPERT
  • 16,334 POSTS

I did look at some bulletins for your vehicle. I did see a service update, under 8 years/80K, warranty. Not sure if I was looking at the proper update?

You might talk to another dealership, ever who answers the phone, ask for the service department, talk nice, explain your problem. See what they have to say.

If the diagnostics showed my work caused the problem, I wouldn't charge the diagnostics. If the diagnostics showed an unrelated problem. I would charge for the diagnostics. I don't know how a dealership would handle problems like this? I know a lot of shops charge around 100 bucks or more for diagnostics, even if they don't fix the problem.

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Thursday, November 16th, 2017 AT 3:10 PM (Merged)
Tiny
M0RDECAI89
  • MEMBER

So there is no way to reset the ECM to factory settings myself, it would have to be through the dealer?

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Thursday, November 16th, 2017 AT 3:10 PM (Merged)
Tiny
JDL
  • EXPERT
  • 16,334 POSTS

That's the only way, I know. I'm not sure they could undo it, or would.

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Thursday, November 16th, 2017 AT 3:10 PM (Merged)
Tiny
M0RDECAI89
  • MEMBER

Why do some posts say you can reset an ECM by disconnecting the positive battery cable for 3 mins and then tapping it on the post 3 times? Is this only true on some cars?

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Thursday, November 16th, 2017 AT 3:10 PM (Merged)
Tiny
JDL
  • EXPERT
  • 16,334 POSTS

I've never heard of the tapping part? I have heard of taking a cable loose to erase codes. If a service bulletin told me to take the cable loose for some diagnostic procedure, I would. I can't say that taking the cable loose will help or hurt?

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Thursday, November 16th, 2017 AT 3:10 PM (Merged)
Tiny
BROCK1976
  • 2007 CHEVROLET COBALT

Computer problem
2007 Chevy Cobalt 4 cyl Front Wheel Drive Automatic 23,000 miles

Please help, my 07 4 door cobalt, has left us stranded a few times, Chevy garage has been working of this car off and on for about 2 months, the car started by all power going dead and key getting locked in the collumn, no signs of power anywhere, no lights just dead like it didnt even have a battery, just wait a few minutes and power comes back on, garage said its the ecu, so they put a new one in it, 3 weeks later, started doing the same thing, sometimes I would have power but wouldnt crank, so I could jump it and it would start, took back to garage a 2nd time, they said its the battery, so I replaced it, 8 days later the car power goes out, and comes on and wont start, couldnt even jump it this time, I checked all fuses and relays they worked correctly but I noticed I had no power to the starter this time, just dropped it off for 3rd time chevy garage and they said its the ecu again, I asked them to find why and they said they dont know, nor would they ever, so im at my witts end, please help, if anyone has ever ran accross this kind of problem, thanks.

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Thursday, November 16th, 2017 AT 3:11 PM (Merged)
Tiny
ATKAPARKING
  • MEMBER

Are you taking this vehicle to the dealer? If not, make sure the shop has a Tech2 scanner--this is the factory GM diagnostic tool. Other scanners can cost thousands of dollars but are still not in the same category as this factory scanner.

These computers should be covered under warranty. If it's not a dealer, the shop may be using after-market computers which often have quality control problems. I would recommend taking this vehicle to the dealer and fixing it with factory parts. Good luck

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Thursday, November 16th, 2017 AT 3:11 PM (Merged)
Tiny
BROCK1976
  • MEMBER

Yes it has been going to the gm dealer, the car was slightly wrecked in front, so its not under warrantee, but a gm tech should be able to find the problem, it amazes me they have no clue?

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Thursday, November 16th, 2017 AT 3:11 PM (Merged)
Tiny
BROCK1976
  • MEMBER

Yes it has been going to the gm dealer, the car was slightly wrecked in front, so its not under warrantee, but a gm tech should be able to find the problem, it amazes me they have no clue?

Ps the new ecu I just bought is under warrantee for 12 months, they are currently putting the 2nd new one in today, I just figure it will go bad in a couple of weeks, like the first one.

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Thursday, November 16th, 2017 AT 3:11 PM (Merged)
Tiny
ATKAPARKING
  • MEMBER

I think the ecm will function well--they do go bad out of the box, but it's rare to have that happen twice. The question is, will the ecm fix the car or does it have another issue. Often a tech will spend an hour on the car, become frustrated that he can't find the problem while his buddies are making lots of money on services and timing belts, and so he says, "Needs a computer!" The car is out of his stall and the headache put off for another day. Also, you have no control over who works on your car. Is it a competent tech who will go the extra mile to find the real problem, or is it some lot lizard who put in a couple years washing and parking cars at the dealer, went to tech school and is now working with the big boys, but still doesn't have much of an understanding of electricity flow and the patience needed to track down a problem of this sort, and since he's low down on the totem pole, he paradoxically gets the less profitable and more difficult repair work. These types of dynamics do occur at dealerships--they shouldn't, but it's not a perfect world. By understanding what's going on behind closed doors hopefully you will be in a better position to influence your car's repairs. If your car acts up again, I would recommend talking to the service dealer--politely, briefly documenting the repair attempts on this vehicle, and then request a GM tech who has done this for a decade or more. If they waffle or squawk, call another dealer and see what they can do for you. Good luck

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Thursday, November 16th, 2017 AT 3:11 PM (Merged)
Tiny
BROCK1976
  • MEMBER

Thanks, that is helpful, the orginal ecu had 20,000 miles on it, the 1st one replaced by gm worked fine for about 200 miles, and yet to see about the 3rd, you make a good point on the possibilities of bad ecu out of the box, anything is possible, one good thing, the same tech has worked on the car, so its not been around the garage, if it happens again, i'll try another dealer, only time will tell of the 2nd ecu out of the box, thanks man.

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Thursday, November 16th, 2017 AT 3:11 PM (Merged)

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