Are there any factory installed accessory power installed in the H3? I want to hard wire my radar detector and don’t really want to cut up the factory harness. My last car (corvette C5) had this option (inside a compartment there were there wires a switched positive, a positive and ground, all you had to do is tie in the new wires and you were ready to go) it was great. Any help would be great.

Are there any factory installed accessory power installed in the H3? I want to hard wire my radar detector and don’t really want to cut up the factory harness. My last car (corvette C5) had this option (inside a compartment there were there wires a switched positive, a positive and ground, all you had to do is tie in the new wires and you were ready to go) it was great. Any help would be great.

The infamous Radar Detector wires, located just above the I/P fuse block. They were handy for hard wiring in the Escort or Valentine, the two favorites of the Corvette owner.
The Hummer has four wires under the I/P on the driver's side, but there is no Ignition Hot, only a battery hot, ground, brake signal and trailer brakes.

I can tell you what I did which was not that invasive to the wiring.
I mounted the radar detector just to the left of the rear view mirror. Then ran the two wires under the top windshield trim to the driver side A-pillar.
(The A-pillar molding is held in place with one screw, under the cover, and some retaining clips. Just remove the one screw, and pull, very easy to remove.)
Inside the A-pillar is a wiring harness that contains some wires, depending on your option content of the vehicle.
With the dimming/temp display rear view mirror:
Ignition Hot wire: Dark Blue/White stripe this wire is run through a 10A cruise/misc fuse, via the RUN/CRNK relay and supplies B+ whenever the ignition is in run.
Ground: Black/White stripe

If you have OnStar, do not tap into any of the following wires:
Brown/white (Keypad RED LED signal)
Yellow/Black (Keypad GREEN LED signal)
Dark Green/White (Keypad call answer, OnStar, Emergency signals)
Light Green/Black (this is the OnStar supply voltage for the OnStar mirror switches and I might be only five volts; not sure).
Again, I do not recommend tapping into any of the OnStar function wires.
Ground for the OnStar functions is also a Black/white stripe, but it goes directly to a ground point so this is NOT a problem.

If you have the sunroof, you can tap into the same wires I used:
Yellow: Ignition Hot through the S/ROOF/FRT/WPR fuse fed via the RAP relay, so the detector stays on after the ignition is off, but goes off when a door is open (retained accessory power function).
Ground: Black

I took the tape off the wire protector conduit, and used small butt end connectors to tap into the wires. Then I re-taped the conduit, installed the A-pillar. I did have to epoxy the suction cups to the window. For some reason, even new suction cups would not adhere to the window...drove me crazy. So, I just applied some epoxy, let it sit over night, and attached the detector, and in six months, it has not fallen.