Adding factory key-less entry

Tiny
ROBDANDREA8
  • MEMBER
  • 2008 CHEVROLET TRAILBLAZER
  • 4.2L
  • 6 CYL
  • 2WD
  • AUTOMATIC
  • 99,000 MILES
I am trying to add factory key-less remotes to the vehicle listed above, that didn’t come with this option. Do you think it would be possible to pickup a BCM from the junkyard from a TB that had the option and simply drop it in my vehicle? I have access to a 2004 TB that I could use to program the remotes to the new (junkyard part) BCM if that would help get the factory remotes to work with my TB. I am assuming I need to replace the BCM under the driver side rear seat. Thoughts?
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Monday, June 3rd, 2019 AT 10:13 PM

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Tiny
STEVE W.
  • MECHANIC
  • 12,883 POSTS
Welcome to 2CarPros. Getting the OEM system to work requires the LGM, PCM, and the correct remotes. The rear lift gate module (LGM) has to be one with a remote receiver in it, the BCM has to be programmed to match the vehicle and have the key-less option enabled using the factory option sales code. Swapping the modules between vehicles won't work because the modules are VIN coded due to the anti-theft system.
To throw another wrench into the mess, there are three different remote types as well. There are low frequency, high frequency and single frequency units. They are dependent on which other options you have and need to match the frequency the LGM uses.

All of this is why even the dealers who add a "factory" key-less entry system to a vehicle that didn't get built with that option actually don't use the OEM parts. They use a "dealer option" kit from an aftermarket (usually DEI for GM) supplier that comes with remotes that look like factory units but are really not.
If I was doing this I would likely get the kit through a dealer and install that rather than fight with the factory parts. The first thing I would advise would be to run your VIN and see what options you do/don't have. I have seen more than a few times that all the hardware was there for an option like key-less entry but the buyer didn't want to pay for that so the dealer just kept the fobs that came with the vehicle! Next would be a scan with a dealer level scan tool to verify which modules you have. Then go from there. If your vehicle has TPMS, it may have the correct LGM in it but you would still need to scan it to see which option that module has.
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Tuesday, June 4th, 2019 AT 4:56 AM

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