Adding remote door lock system? Module needed?

[movietvet]

I have been doing auto/light truck work for close to 45 years and so many times, when I was doing work behind a door panel/card, I ran in to crappy installs of add on remote door lock/unlock systems. Linda does not complain but I want to add this option for her. This LS vehicle is a very basic set up and even though it has power windows and power mirror adjusting features, it does not have power locks and never came with them. I have had it at a very reputable locksmith shop and they verified there is no module for the remote door locks.

So, knowing all this, tell me the BEST way to get this remote door lock/unlock feature to Linda's 2002 Trailblazer LS. Give me quality system recommendations. If can supply link(s) to the system install, even better. Thanks in advance.

 

[movietvet]

I need to edit this. Both front doors have power door lock buttons on them and when the front doors are unlocked, you can press the interior unlock buttons, on either front door, and the rear doors and rear hatch will unlock. the rear doors do not have interior lock/unlock buttons on them.

We were told, by the locksmith, that the reason he could not get his new door lock key fobs to synch up and work is that the Trailblazer does not have the module for it to allow for key fobs.

Does that make any sense to anyone here? Ever heard of that?

 

[azswiss]

Yes. Based on what I have read (on this site) key fob comms and remote entry involve multiple modules including (though likely not limited to) the BCM and, in the case of my '03 Suburban, the passenger module interacting via the Class 2 Serial bus.

The best source for details is @TJBaker57. His post in this thread: Hidden fuse/relay box (post #17). offers a good overview (note LGM is Lift Gate Module):

So how does the keyless entry actually work?

The key fob sends out a radio signal when a button is pushed. The radio message contains the key fob ID of some sort and the details of what button has been pushed.

The LGM has the radio receiver for the keyfob radio signal frequency. The LGM will check the key fob ID to confirm that the particular key fob is recognized and registered to this vehicle. If yes then the LGM puts a message on the vehicle network to "wake up" the network from a sleep state. Even when the key is off the modules still have power and are monitoring the network for traffic.

The BCM receives the "wake up" message and broadcasts a "power mode" message to the network. This notifies all modules what the desired operational state of the vehicle should be.

The LGM follows up the "wake up" message with a functional message that details which key fob (driver 1, driver 2) was used, and what function is being requested (lock, unlock, etc.) and so on.

The BCM is programmed to act on this second message sent by the LGM by responding with a different functional message directing the relevant module(s) to perform the action requested.

He speculates that the remote entry function involves not just hardware but RPO-specific (e.g. RPO code AU0 on my '03 Suburban) programming as well.

 

[movietvet]

I looked and the Trailblazer RPO code AU0 is not on that sticker.

So, in this case, I guess I have to get a kit for and install, that has it's own module. Correct?

If that is the case, are there any recommended kits?

 

[Mooseman]

The FOB receiver is in the liftgate module. To get this working, you would have to replace the current non-RKE module with one from a known GMT360 with RKE and then reprogram the BCM with a Tech 2. After that, program some fobs to it, probably using a Tech 2 again, unless the fobs came with the module, maybe.

Or, you could just get an aftermarket system. Either just an RKE alone or a remote starter with door lock option. Can get pricey with the system, an interface module and security bypass, if it works with a BCM without the RKE option.

 

[azswiss]

My inclination would be to take the aftermarket route.