2011 GMC Acadia won’t start after engine replacement

Engine locked up so had the motor replaced now it appears that the security system will not let the vehicle start. Have had locksmiths come over they couldn’t reset the key NOW WONDERING WHAT TO DO NEXT. (Mechanic is able to jump it however won’t key start) please :pray::slightly_smiling_face: help

Try doing the anti-theft relearn.

Here is the relearn:

  1. With your key, turn ON the ignition, with the engine OFF.
  2. Observe the security indicator, after approximately 10 minutes the telltale will turn off.
  3. Turn OFF the ignition, and wait 5 seconds.
  4. Repeat steps 1-3 two more times for a total of 3 cycles or 30 minutes.
    Important: The TDM learns the key transponder information upon the ignition switch transition from OFF to CRANK. You must turn the ignition OFF before attempting to start the vehicle.
  5. With a master vehicle key, start the vehicle.The vehicle should now start.


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You may need to contact a GM dealer to have this worked out. I bet there’s some kind of conflict with the “computer” and the new engine, some sort of mismatch.

A locksmith can really only help with ignition keys and door keys. I’d be surprised to find one that can fix security issues.


Just some food for thought. Recently I had to replace the BCM in my Sonoma truck. I do NOT know for sure if your vehicle uses the same process but my Sonoma has 3 different key relearn procedures.

The first was supposed to be the correct one. It was not. I ran that procedure twice with no key function. I ran the second one once, fired right up, and has been fine since with no CEL or SRS lamp illuminated.

I could really go on a tear here about GM idiocy not involving the relearn but there’s not enough bandwidth…

OP did not change the ECM. What info is computer expecting to get from motor?
Motor is cranking? You have verified there is no ign pulses or fuel pressure/injector signal?
It a 3.6 motor. Same year donor?

One of our cars was stolen in 2010. We didn’t trust that the thieves or someone that got the key from them wouldn’t just drive off with it again. We had the security system altered so that the old key fob couldn’t open the doors. There was one locksmith in Central Maryland authorized by law enforcement to do that. We hired him to do it and change the locks so that the old keys didn’t work either.