Wiring harness help (GMOS-01) on '05 Pontiac Grand Prix

[Stormhaven]

I have almost completed the connections to my wiring harness for my aftermarket HU on my 2005 Pontiac Grand Prix. New Pioneer AVH-X8500BHS to compliment all new alpine type-R fronts and rears. The problem I have involves 3 wires not mentioned in the provided install instructions. From the 24 pin harness an orange wire labeled "Illumination/Dash Light" and an orange w/ white stripe wire labeled "Dimmer" don't appear on the wiring diagram and have no mention anywhere in the instructions. Do I leave them alone or do they need to be installed somewhere?

The last wire is on the 16 pin harness (the one that gets connected to the radio wire harness). There are 2 red wires labeled "12 volt ignition/switched" coming out of the addapter. Do both get tied into the red wire coming out of the HU or do I leave one not attached to anything and seal it off?

Any help from those that have GM installs in the past would be of great help.

Thanks in advance...

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[trumpet 5,000+ posts]

The GMOS-01 manual and similar interface manuals have really clear instructions. They're not 100% free from errors.

Your head unit should have an illumination wire. Connect that to the orange/white wire on the 16-pin GMOS-01 harness. The dimmer wire can be taped off. You should only need 1 of the red wires to switch on the radio, so tape off the other one. You should test the radio before putting the dash back together.