not sure on relay, but there has to be another hot lead switched off the ignition. maybe try running a jumper to the wiper fuse location OFF the load of the other fused lead that is controlled off the ignition. if all the ignition leads don't work then I'd imagine the switch itself or possibly a relay as u said. not familiar with hummers or really ignition relays in general but I am an electrician and it makes sense to start with an easy troubleshoot and go from there.
my wife's jetta had a similar problem, with the factory monsoon or bose stereo whatever the hell it was, it would shut off when you open the door even if the key was completely removed it'd still wait til the door opened to shut off. then, when changed to an aftermarket dvd player it wouldn't shut off, I searched online and finally came to just run a wire to the fuse box off something that came off the iginition switch, don't even remember what, I just stuffed the wire under one of the fuse legs, ran it all wild over the fuse box lol. just was tired of the batteries dying and didn't care how it looked. I could've done it cleaner in the back tied to the other wires and use a T-tap to tie it into a wire, but what fun would that've been lol. anyway, good luck!
Last edited by hawaiianbasshead; 04-06-2009 at 02:27 AM.