Is a doorlock module always necessary?

Hi- I'm new and have been reading up- I have installed a remote starter on a 2002 C/K and tapped into the rear of the relays for the door lock controls- I have a 2004 C/K to do and as I research it - every where I go it says I must use a databus interface  to do it- Even on the 2002 C/K charts -it says use the 456g module- yet I just did one- bypassed the theft deterrent like I always do with a GMatta II .  I have access to all the GM vehicle service manuals, and the wiring schematics still show relays used in the 2004- so why can't  (or can I) tap in to the rear of the relays on a 2004?  I realize the factory alarm will/can go off if you don't a;ways use the remote to lock AND unlock the doors.  So I just tell my owners to always use the remote- never lock the door with the door switch- wait till door is shut and use the remote.  I don't care about any other features like seat heaters and the like.  I guess the bottom line is I can't see paying big bucks ($50+) for the 456G, when I think I can still tap into the relay circuit for the door lock management.  I know the 456g is probably faster install etc, but to the common man- is it worth it?    Also, what about the GM U7 module which is supposed to do it all- maybe this is the way I should go- only buy one module kit-  any thoughts- and thanks for the great forum..Brcidd - Engineer That Does Remote Starter Installs on the side.

On the 2004 you need to do reverse polarity inside each of the front doors. If it is a 4 door then the rear doors are negative and you can trigger the relays for those. Or you can solder wires to either the drivers door lock switch board or solder wires directly to the factory transmitter, but you will lose the use of that transmitter obviously. You cannot rearm the factory alarm if you do it the first way mentioned. So it seems clear to me: Buy the module and charge the customer for it. It is so much easier to install too.J Rilla

Owner/Installer

DEI 456 will lock, unlock, arm, disarm, and do domelight supervision. It takes just a couple minutes to install rather than removing door panelsOh...about an hour.

Try the crimestopper unit. I have never used it myself, but I would try it. J Rilla

Owner/Installer

try using a crime stopper gmlku databus module along with your install. They are exspensive,dealer cost is about 24$. I charge 65$  installed for this product. Its the only way to go and it is the corrrect way to do it. As far as the price goes for your customer it should be justified because considering the cost of some of these new SUVs , an extra 50$ should be no problem.Solartech Window Tinting & Electronics Inc.

If the truck is a 4 door, there will be a plug under the BCM behind the air duct. Locations B2 and B3 are empty you can use those for (-)lock and (-)unlock. If you have an extra alarm harness DEI, Audiovox, etc, pull 2 wires out of the harness by releasing the pins. Slide the pins in the empty slots. If you have the time you can order the pins from Delphi.ASE Certified