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My ECU recently went bad with codes p0606 P1606 p0605 and a couple others. The car still started and ran but with a very rough idle and very little power. After getting a used ECU cloned to my car, the car ran with the exact same conditions but no check engine light or codes. I took it to my mechanic for diagnosis and he discovered that while it is running if you quickly cycle the key from the run position back to the on position and immediately back to run, the car would idle better and regain all of its power. Likewise, if I put the key in and turn to On position and wait a second or two the car will have the rough Idle, whereas if I put the key in and turn as fast as I can to Run it will run perfect. He suggested I install a new Ignition switch and I did, only to have the same problem. Any ideas what would cause this? I felt like the ECU replacement was a waste so I put the old ecu back in and I could not remedy the condition by switching the key position, so i know there is a problem with the old ECU. The situation seems a bit odd to me. I am not sure if there is anything else I should consider checking.....Any input would be greatly appreciated!
 

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These are internal ECM errors. P1606 is a CPU fault. A "couple of others" might be important. ;)

1) There's no guarantee you cloned a good program + data image from the original ECM with those faults.
2) Your mechanic might have stumbled on a way to get the ECM to fail over to limp home mode. This uses non-optimized fixed engine mapping in different physical memory. It might work better than what's in either ECM.

My suggestion would be to flash a new, known good image into the replacement ECM and see if that fixes the problem. You could also use a similar MY ECM w/o cloning it, provided you can marry it to the car (flash the VIN and other car info).
 

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Thanks for replying! I would have included the other codes if I could remember them, I lost my original print out. I will run it by my mechanic and call the shop in Illinois that cloned my ecu. I originally sent it in for repair and was told i needed a replacement. I asked how it was possible to clone a ECU that was bad and they assured me the cloning process went fine. One other thing that seemed odd was that the replacement ecu they sold me looks the same but has a different part number. They said it was fully compatible as the hardware is exactly the same and the only difference was software.

I am also not 100% sure what you mean by: "You could use a similar MY ECM w/o cloning it, provided you can marry it to the car (flash the VIN and other car info)." Thanks again for replying!
 

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All the T8 ECMs are the same from a programming standpoint. There have been 4 or 5 hardware revisions, and they've been produced in a number of places. It is possible they cloned the old ECM just fine, maybe by refrigerating it, but it already had a corrupted image from the other faults.

To marry a used ECM (without cloning the old one into it) to your car, you have to enter VIN, market, etc. with Tech II. You also have to have unmarried your old ECM from the car with Tech II first. You'll need SPS to flash a different/latest image into the ECM. All this requires additional software on PC that talks to the Tech II.

So you (or someone) would need Tech II and additional PC + software, plus some time, to do all the above.
 

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Can u ask ur mechanic if he have tech2 device and globalTIS to update the car ECU ?
If yes, let him update the ecu to latest software, provide the current sofware numbers from the ECU and the numbers after the update
 
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