Security light stays solid/always on?

Tiny
JUWANSAYLES
  • MEMBER
  • 2001 CHEVROLET TAHOE
  • 5.3L
  • V8
  • 2WD
  • AUTOMATIC
  • 255,000 MILES
I replaced the fuse and got a new Anti-Theft Vats Security Module but still SUV starts and immediately shuts off, and no response when I press the lock or unlock button on key fob.
Tuesday, August 5th, 2025 AT 10:30 PM

7 Replies

Tiny
KEN L
  • MASTER CERTIFIED MECHANIC
  • 54,137 POSTS
Is the security light flashing? If it is flashing the system is enabled. I would try a hard system reboot. Also, do you have another fob? It could be the batteries inside the fob are dead. We can run the codes with a CAN scanner to see if the security system is working or what codes are involved. This video will show you how:

https://youtu.be/u-4syLc-ifQ

Here is the guide to show you how to do the hard system reboot, this will clear the system out.

https://www.2carpros.com/articles/step-by-step-guide-performing-a-hard-system-reboot-for-your-vehicles-electronics-systems

Please upload pictures or videos in your response.
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Wednesday, August 6th, 2025 AT 11:38 AM
Tiny
JUWANSAYLES
  • MEMBER
  • 16 POSTS
Changed battery in keyfob, no change, did every system reboot in the giving instructions, and still no change
Only codes im gettin is for some 02 sensor and camshaft sensor, I been gettin them codes.
But my security never was flashing, it's solid, as in always on never off until I disconnect the battery
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Wednesday, August 13th, 2025 AT 6:22 PM
Tiny
KEN L
  • MASTER CERTIFIED MECHANIC
  • 54,137 POSTS
If the security light is on solid that means it means the system is in stand by so that may not the problem. To be sure we should do a CAN scan which is not a regular scan, please go over this video so you can see.

https://youtu.be/u-4syLc-ifQ

Can I ask if the engine cranks over, also there are three fuses that run the security system did you check them all? TBC fuse under the hood, IGN1 and CRUISE fuses in the fuse panel inside.
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Thursday, August 14th, 2025 AT 8:09 AM
Tiny
JUWANSAYLES
  • MEMBER
  • 16 POSTS
All fuses are good, it does crank and start but immediately dies, working on getting CAN scanner now
Could the BCM have gone out or fried?
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Friday, August 15th, 2025 AT 6:56 AM
Tiny
KEN L
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O ya, this does happen, the CAN scan should pinpoint the issue. You can get a preprogrammed BCM from Flashmasters for like $200.00.
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Friday, August 15th, 2025 AT 12:17 PM
Tiny
JUWANSAYLES
  • MEMBER
  • 16 POSTS
Bought a CAN scanner but due to me unhooking battery and the truck starting but immediately stalling after starting, I have no codes or lights on the dash at all but the security light, I did by one used BCM from ebay to see if something would happen. I notice that the one I pulled out my truck, had a couple burned spots on it, idk if they should be there or overtime it happen
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Sunday, August 17th, 2025 AT 7:05 PM
Tiny
KEN L
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A used BCM will need to be programmed to the truck, this is why I suggested Flashmasters. Also, I cannot see the burn marks on the board but any burn marks are not good. I think you found the problem.
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Monday, August 18th, 2025 AT 10:46 AM

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