Chevy Trailblazer Rear Hatch Lock

I have an 04 Chevy Trailblazer and I am using a remote start unit by Micro 2001 and a 457G interface.  I can get the doors and hatch to unlock.  The doors will lock,but the haatch will not lock.  The doors and hatch wire in the five wire configuration.  My question is can I go in and wire a relay on the lock side of the hatch motor? If yes how can I do it and not ave to rewire the whole truck?

I have tried everything that I can think of and called a micro installer tech ( who told me to fve wire the lock side) and I still can't get it o work right. I can cut the wire on the lock side and wire in a relay but not using the wire coming from the switch and the door will lock, but as soon as I hook up the switch to 87a it blows fuses.  Is it possible to have a bad module even if it still works the other doors? 

There was an earlier post about this on the site somewhere...I don't have the link but the posters described basically the same problem(i.e. using a 457GW and the hatch lock wouldn't work right.) I think they said that DEI was working on a fix, and that in the meantime you should make sure that your ground is good, or try activating the (-) lock and unlock inputs with relays instead of directly from the brain.C Renner's Auto Electronix

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Thanks for the help this one has had me for a little more than a month.