2007 Cadillac CTS 3.6L used ECM replacement and programming

David Owner/Technician Kitchener, Ontario Posted   Latest   Edited  
2007 Cadillac CTS 3.6L (7) 5-spd (5L40-E)


I have a CTS that I need to replace a ECM on to fix a misfire and some other codes.

I had installed a used PCM and found the vehicle will not crank and the key will not come out plus communication goes down on the data bus with all modules except engine and transmission.

I figured the used ECM needs programming and necessary relearns as well.

I went to acdelco tds and installed the software as required.

I tried to do a replace and program of the module with a Cardaq M but kept getting a unkown error and now severe error.

J2534 tool box no longer identifies vin on used ECM. 

I see from this and other forums that this seems to be a common issue with used modules.

Can anyone shed some light as to whether I had a bad or incorrect used ECM. My supplier says its correct 

but was unable to verify its prior functionality. I have serious reservations about trying another used one.

Is there a possible way to attempt to salvage this ECU ? Do you think I had a faulty one ?

Is my best option to try a remanufactured one ?

Antonio Owner/Technician
Nutley, New Jersey
Antonio Default

Try a Remanufactured one or send the original one to any place to refurbish it. I dealing with the same issue like a year ago and used Modules are not welcome for this Car, I try everything with Drew Tech and was a waste of time and money.

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Azam Technician
Waterbury, Connecticut
Azam Default

I never seem to have any luck programming used pcm on the these cars. I always get a new one. I

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Antonio Owner/Technician
Nutley, New Jersey
Antonio Default

True Story

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Tomi Diagnostician
Chicago, Illinois
Tomi Default

Your used ecm is junk. These are known for having network issues. You have no issues with used modules on this year. If you do get another used one scan it first if it comms with your scan tool it will program fine. After your program with sps you will need to relearn antitheft. You can also do that with sps.

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Robert Mobile Technician
Newark, Delaware
Robert Default

It is normal for the key to be stuck in the ignition when the engine control module is not communicating on these vehicles. These modules are garbage. They typically will fail in that manner where you can talk to it but every other module has U codes. If you have all powers, grounds, can, and wakeup circuits functioning then you need to try another module. I have seen gm reman units fail within…

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John Owner
Petal, Mississippi
John Default

Most used ones are junk from my experience u can installed used in this car have done quite a few I would suggest buying a new one from dealer they are very inexpensive I believe about 200 dollars and u will save a lot of time and get the car out quickly

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John Technician
Sarasota, Florida
John Default

Do not roll the dice with a used module. I went thru this last week with a used car dealer. Brought me 2 used pcms. Neither one was any good. Ended up getting one from Cadillac in the end. Total waste of time. As others mentioned the failure rate is very high on these and difficult to get a good used one in my experience.

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Phillip Owner/Technician
Fresno, California
Phillip Default

The best way I find to install a used PCM is to take the BCM offline. program PCM with correct vin number and then bring the BCM back online .program security for both BCM and PCM and it works for me. The BCM is the interpreter module that controls high and low speed communications. It will disable communication if it sees a different Vin number or go into protection mode. The BCM the only…

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Antonio Owner/Technician
Nutley, New Jersey
Antonio Default

In this specific PCM are a lots of common problems, like Key sticks in, no crank, no start, is a huge possibility that the one from the Junkyard have the same issue also and for the price of a new or rebuild one, don't worth take the chance.

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David Diagnostician
Philadelphia, Pennsylvania
David Default

Probably a bad used PCM. Go New or remanufactured

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Michael Owner/Technician
Grand Rapids, Michigan
Michael Default

Used ecm is bad. I have used a few of them most recently do to gm strike i could not get a new oem unit. If at all possible i would get a new one from gm. They normally have them in stock in my location.

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Ruben Technician
Skokie, Illinois
Ruben Default

make sure you have a good ground by the ECU if you loose ground the ECU get fried when you turn the key

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Brian Instructor
Parma, Ohio
Brian Default

I have done used ones of these,however just getting a used one that communicates, and has a SES and lets the key turn off, or is not bad is the 1st challenge. 2nd challenge is programming these used computers and that is 2 parts in itself. First getting the used module to even start programming, then getting the security to learn. All this said believe it or not a few years ago there was a…

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Richard Technician
Stony Brook, New York
Richard Default

As you have heard, these PCM's have a high failure rate. I would get a reman next. Or perhaps send out the old one for repair. But I think the reman option would be quicker.

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