2005 ctsv , ecm issue? plz read

hello everyone,

this weekend 9/16/18 i encountered a issue i can not seem to find an answer for , forgive me if i've overlooked but can only research so much in a tight window

So, i offered to help a buddy tune his 2005 ctsv after he got it back from a local shop ($7,000 later) his stock ls6 gave out and the shop swapped in a ls2 , i am unsure exactly what all went on with the swap, it appears maybe ls6 intake and injectors but again not 100 percent sure and either is he. but after he got the car back , idle and driveablility were terrible!

the tune was progressing UNTILL , he got out of his car and bumped the cable, not thinking anything about it as he pushed the cable back into the diag port, i went to write calibration , the computer went to 4% and said timed out also gave us the security warning on the radio screen and on the dash, now the car will not start, hptuners will no longer communicate to the ecm (datalink protocol fail or protocol not detected) i can not connect to car to perform a scan, i can not write another calibration or read current file, is the ecm fried?

also i was able to clear the theft detection warning off the radio screen, but if i try to hook up laptop to ecm it will come back , the car is obviously a no start condition, luckily i have a spare ecm on hand from i believe a 05 express van that i got for a swap into my 54 chevy but i have never installed this ecm to know if its in good working order, if i install it can i just do a security relearn on it or what all needs to be performed? also thinking maybe install stock computer back and performing the security relearn?

any help is much much appreciated !

thanks Travis.

Don't unhook the original PCM yet. Try to do a calibration write in low speed. If that doesn't work you can try taking the navigation fuse out which is located under the back seat on the driver side.

hey james

what if i already took out the original ecm?

also im pretty sure hptuners was not able to connect at all to ecm, thats when it says protocol failed

Hard to say. Need to see if you can bench flash it now.

You can do a write entire of the stock file from the cts-v into the new PCM and it should take and function like the original PCM.

before i do a write entire on the new ecm, i need to do the security relearn tho correct ?

No.

hey five finger, ok so just plug in replacement ecm , and do a write entire? is there any options to try with the stock ecm?

-so just to kind of recap i did already plug in the spare ecm, the system gave me a "starting disabled" on the radio
-the factory ecm if i plugged hptuners in, no matter if i read ecm, write ecm, or connect with scan tool would give me the "security theft" light on the radio

thanks again

With the new PCM you'd have to license the new file, then write your old file with a write entire over it. You can't write files to a computer without a license.

If you can write to the original computer have you tried disabling the VATS feature with a write entire yet?

no after the little incident, anytime i tried to connect the laptop to the ecm it would throw that security fault, so i cleared the security fault and tried to jump the starter to see if it would start that way, no luck , i wasnt sure if maybe there was something else that would keep the laptop from connecting to ecm, so i basically jumped to the conclusion that the ecm was bricked (since ive heard all the horror stories of do not bump the cable during a write)

i understand i'd have to license the replacement ecm before i can write to it, which is fine since i plan on keeping this ecm for 54 truck build,

i guess my next question would be , if i just did a security relearn on the car, would the car start on the spare ecm with no write entire performed? just to confirm that the stock ecm is indeed a bricked ecm ?

I would think it would start and run with a security relearn done on the new spare computer.

Not sure what scan tool would make that easier on those CTS-V's.

ok thank you, i guess ill try the security relearn and see if it starts, if it does ill just have him buy a new ecm , oddly enough he called the caddy dealer today and they said they couldnt find a part number for a replacement ecm

UPDATE CAR IS RUNNING AGAIN: after lots of reading last night i stumbled on a post with symptoms alot like mine, apparently this is becoming a frequent issue, but i think mostly with the new MPVI2, while im still using MPVI but i went ahead and installed the stock computer back into the vehicle and performed a "write calibrate" and the first five times it failed all in different areas of the load, the 6th time tho it took the write and car started back up . hope this post helps someone in the future

car was a 2005 CTSV , P59 ecm using MPVI PRO