Tahoe door lock issue

I'm trying to install an audiovox PRO-9675FT4 alarm/remote start module in a 1999 chevy tahoe 4-door with OEM remote lock/unlock system.  All connections are operational with the exception of the door locks.  I'm able to activate the lock circuit with a + signal however the unlock circuit is another story, it does not seem to be a + or - trigger switch.  All diagrams show this circuit as a 3-wire positive circuit but it does not appear to be such. Any help greatly appreciated.

what color wires do you have in the tahoe they should be white and light/blue the relays are above the brake pedal

do you have a 4 door or two door .4 doors are +trigger must get wires in drivers boot  two door are 5 wire

with factory keyless entry you have 3 wire + pulse door locks of the 3 wires one will always show 12 volts  no matter how the switch is presed or not pressed ,of the other two wires one will pulse 12 volts on lock the other will pulse on unlock. the wires are in the driver kick panel the colors are  light/blue and  a white wire. now the only other thing this could be is a 5 wire reversal system and that is in cars without the factory keyless so you should have 3 wire.

Ok  folks, i just got a printout of the vehicle wiring information for a 99 chevy Tahoe from a local installer & it included  a footnote that stated "positive trigger on models with rear lift window,  and 5 wire on models with cargo doors."  My vehicle has cargo doors so if anyone else out there runs into this type of problem, know you're not crazy.  tks mobiletoys2002, looks like you were on the right track.