Anti-theft light stays on, no crank-no start

Tiny
RLVASEY
  • MEMBER
  • 2003 GMC YUKON
  • 4.8L
  • V8
  • 2WD
  • AUTOMATIC
  • 250,000 MILES
The SUV is not used much, so it sits for long period of time between usage. This time it looks like the battery had died while sitting, (maybe two months). Replaced battery, now the anti-theft light is staying on an will not go off unless the battery is disconnected. No crank/no start. I called the local GMC dealer and explained what is happening. I was informed that the anti-theft system had lost its programming and I would have to bring it to the dealership to have them to re-load the anti-theft programming. Does this sound right and is anything that I could do to reset the anti-theft myself?
Friday, July 5th, 2019 AT 9:52 AM

3 Replies

Tiny
STEVE W.
  • MECHANIC
  • 15,233 POSTS
Welcome to 2CarPros.

There is a way you might be able to do this yourself but it may not work. It is the 30 minute relearn. Pay close attention to the on/off key cycles and the step at the end of the third cycle where you need to turn the key off before you try to start the engine. If it doesn't work the first time you can try it again.

1. Turn ON the ignition, with the engine OFF.
2. Attempt to start the engine, then release the key to the On position, vehicle will not start.
3. Observe the SECURITY light, after approximately 10 minutes it will turn Off.
4. Turn OFF the ignition, and wait 5 seconds.

5. Repeat steps 1 through 4 two more times for a total of 3 cycles/30 minutes, the vehicle is now ready to relearn the data code on the next ignition switch transition from OFF to CRANK. You must turn the ignition OFF before attempting to start the vehicle.

6. Start the engine. If it starts and runs normally the process is complete. Test any other keys to be sure they all work.

If the light doesn't cycle off after the first 10 minutes you may need the dealer to re-flash the system.
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Friday, July 5th, 2019 AT 12:00 PM
Tiny
RLVASEY
  • MEMBER
  • 2 POSTS
Thanks Steve W, I had already tried this from another post I found. It did not work, so it looks like maybe a tow to the dealer for this one.
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Friday, July 5th, 2019 AT 12:11 PM
Tiny
STEVE W.
  • MECHANIC
  • 15,233 POSTS
Yeah, if that didn't work the problem is probably a failed module or sensor. A dealer or a good shop with the right scan tools. If the truck isn't driven regularly you might want to get one of the small battery maintainers for it.
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Friday, July 5th, 2019 AT 3:14 PM

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