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How to program a new ECM?

Tiny
SHELLY MEADOR
  • MEMBER
  • 2011 GMC TERRAIN
  • 120,000 MILES
Installed a new programed ECM, tried to program key to new ECM but the anti-theft light does not stay on when I put key in the on position. It comes on and goes off. How can I program my key if the light isn't staying on for me to do the 30 minute reprogram?
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Tuesday, October 25th, 2022 AT 4:14 PM

10 Replies

Tiny
JACOBANDNICKOLAS
  • MECHANIC
  • 109,747 POSTS
Hi,

If the light turns off, it sounds like it is already programmed. Does the engine start?

Let me know. If it was programmed for your specific vehicle, it may not need to be reprogrammed. The body control module still should recognize your key.

Take care,

Joe
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Tuesday, October 25th, 2022 AT 7:40 PM
Tiny
SHELLY MEADOR
  • MEMBER
  • 5 POSTS
The lights turn on. I was told it was programmed for my vehicle, but the vehicle will not start. The company we bought the ECM said all we would have to do is do the 30-minute programming of the key, but they said that the anti-theft light should come on and stay on for approximately 10 minutes for each set then after the third time it should start. However, the light isn't even staying on.
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Tuesday, October 25th, 2022 AT 8:05 PM
Tiny
JACOBANDNICKOLAS
  • MECHANIC
  • 109,747 POSTS
Hi Shelly,

Have you contacted them? The idea that the light should stay on for approximately 10 minutes and then turn off is correct. Once it's off, the engine should start. However, you can't perform that simple procedure because of the light issue.

To me, it sounds like the issue is related to the ECM they sold you. Have you contacted them to explain what is happening?

Let me know.

Joe
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Tuesday, October 25th, 2022 AT 8:20 PM
Tiny
SHELLY MEADOR
  • MEMBER
  • 5 POSTS
I have contacted them. They actually sent me another programmed ECM to try and it's doing the same thing. I'm just at a loss on this.
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Tuesday, October 25th, 2022 AT 8:21 PM
Tiny
JACOBANDNICKOLAS
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Hi,

Okay, can you let me know if this has a 4-cylinder or 6-cylinder engine? I want to do some research related to the issue and the two different options take me in different directions.

Let me know.

Joe
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Wednesday, October 26th, 2022 AT 4:37 PM
Tiny
SHELLY MEADOR
  • MEMBER
  • 5 POSTS
It's a 6 cylinder.
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Wednesday, October 26th, 2022 AT 4:45 PM
Tiny
JACOBANDNICKOLAS
  • MECHANIC
  • 109,747 POSTS
Hi,

Take a look at the pic I attached below. According to my manual, the immobilizer does not need programmed when the ECM is replaced.

So, I need to rewind. What led to the replacement? Were there problems before related to the anti-theft?

Let me know exactly what happens when you turn the key to start the engine.

Take care,

Joe

See pic below.
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Wednesday, October 26th, 2022 AT 6:27 PM
Tiny
SHELLY MEADOR
  • MEMBER
  • 5 POSTS
Was slow getting up to speed, when stopped the car would try to lunge forward and after driving for a bit the flash would flash engine power reduced. Had it scanned at 2 different shops and was told the ECM needed to be replaced. They ordered us 1 ECM and it wasn't working still so they sent us another one. Never had a problem with the anti-theft before.
When we turn the key all the lights on the dash light up then goes off except the service engine light. We spoke with the place we got the ECM again today and they told us that the ECM was programmed with our Vin # for the car and the anti-theft light should be staying on until the key is programmed.
I really appreciate all your help with this. It is my daughter's car and I've been trying to help her. I've replaced ECM's before and never ran into a problem with both being able to program the key to the new ECM.
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Wednesday, October 26th, 2022 AT 6:57 PM
Tiny
JACOBANDNICKOLAS
  • MECHANIC
  • 109,747 POSTS
Shelly,

I am going to run this past the site owner to see if he has any ideas or suggestions. He may talk with me or directly with you, so hang in there.

Joe
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Wednesday, October 26th, 2022 AT 8:32 PM
Tiny
KEN L
  • MASTER CERTIFIED MECHANIC
  • 47,616 POSTS
If the security light is flashing when you try to start it the ECM is not programmed to the car correctly. I would try another company for the ECM replacement. It sounds like they just keep handing you used units.
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Thursday, October 27th, 2022 AT 10:58 AM

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