'05 Hummer H2 RS/Alarm Install

Hello All, I'm in the process of installing a Viper 791 in my H2 SUT and had a question on some of the wiring. On all the wiring diagrams I've seen they list two accessory wires, a brown and a orange that both come out of the ignition harness. I assumed that one of these powered the HVAC system, but when I disconnected both of them from the harness and started the vehicle, my climate control system was still functioning. I did get a message on the system computer to service the onboard air compressor. Does anyone know what these two wires are for? They both exit the key switch harness and go into the back of the inside fusebox along with the white 2nd ignition wire. I'm hesitant about hooking them up as the 791 has only one acesssory out wire and I would havve to diode or relay to keep them separate. TIA -Todd

Here is what I have:

ACCESSORY /HEATER BLOWER 1....ORANGE (+)

ACCESSORY /HEATER BLOWER 2....BROWN (+)

MO

Don't Learn from Others Mistakes

You Might Be the One That Knows.

I have done a couple of 05 H2's and if I recall correctly, you will definitely need to connect both ACCESSORY wires for everything to function properly.  I just wired up an additional relay rather than diode-isolating.

you don't need the brown wire for R/S, but make sure conect the white and orange.how own your mind, control your life.

MECP certified. always use a DMM

Ok, thanks for the help guys. I'll just play it safe ans wire both of them in. I have a 2nd acc. 200ma ground out on the module that I can use to drive a relay.

The white most definitly, transmission damage will occur if you don't.Tacomacrew