2010 GMC Terrain 2.4 - ECM replaced but cannot perform security key relearn

2010 GMC Terrain 2.4 - Had a stalling over fuel situation when warm and after all codes, timing chain etc were repaired I decided to replace the ECU. I received the ECU from Flagship One (preprogrammed for the vehicle). Here is the result:

The ECU was installed, battery connected and when you turn the key on the security light should be lit on the dash and you perform the security key relearn process. Of course the vehicle won't start until relearn is complete, but the security lamp is not lit. I know the lamp is good as it illuminates for a couple seconds (with all the other dash lamps) but then goes out.

I have a Autel MS919 scan tool and have PDF reports of the following:
1. ECU codes: Crankshaft relearn not run (which is normal because the vehicle has to start first, and P0633 Immobilizer key not programmed.
2. BCM (Body Control Module) live data.
3. ECU Immobilizer live data
I am not great on analyzing all the data, but to me the BCM sees the master key in the ignition), and I believe it states relearn is in progress. I reinstalled the original ECU and the vehicle starts fine. I returned the ECU to Flagship one and they sent me another ECU (I requested a different one to verify there wasn't some internal ECU circuitry issues, but cannot be sure they didn't just reprogram and ship back.

I received the second ECU and the same problem (security key not programmed) error. I am attaching the scan tool reports. Any assistance would be appreciated. I cannot find a single web search item for this issue. My opinion is if the original ECU starts the vehicle fine the BCM, immobilizer module and wiring must be OK.

I do a lot of mobile programming. Seen this issue many times. 30 minute key won’t work. Has to be done with a j box or gm mdi it’s 10 minutes

Thanks for your response. So I understand correctly, this process would be the same as programming new keys to the vehicle? And this would require towing the vehicle to a GMC dealership to get it performed (or can locksmiths handle this also)? I could put the old ECM back in and it will drive but stalls out, but a dealership may not want to install the customer 3rd party obtained ECM, and I am not 100% sure that the new ECM will correct the issues.

One last question, you mention you have seen this many times. I watched dozens of videos where the relearn process worked on the same make and model. What could possibly cause this issue on certain vehicles (circuitry or software issue with the ECM)?
Thanks again!

A shop I do does a lot of gm computers I’m equinox and terrain around same year. They try 30 minute relearn. They say light never comes on then I have to program it with sps2. I’m not sure why they don’t work. But have seen it a lot.

Do you have a j box? With your autel??

Cheryl wrote:

Do you have a j box? With your autel??

This was my first thought as well. I've used the same VCMI (vehicle interface) with Techline Connect and had no issues doing programming or security learning.

Before towing it to the dealer, I'd beg/borrow/steal a laptop if you don't have one and try to get TLC to work. :lol:

I have sane problem with my 2011 GMC terriain. How did you fix your 2010 GMc terrain?