2002 trilblazer liftgate module?

My rear wiper blades, rear washer, tag lights and lock for the rear liftgate do not work. Also, my remotes stopped working. All at the same time. I can lock the doors manually, but no where to lock the liftgate. Dealer wants $500 to troubleshoot and repair without parts.  I'm thinking the liftgate module, but not sure. I desperatey need help as I can't lock the liftgate. Any suggestions, diagrams, pics and locations area all needed for the DIY.  Much appreciation.

I've never had the liftgate apart on one of those, but you should be able to do some basic troubleshooting with a test light or multimeter, if you know how to use one. If you could get a wiring diagram for the liftgate module, that would be very helpful, although you could still do a few tests without it. I would start by taking the inner panel off and finding the module. GM usually uses orange for constant power, and black for ground. Start there and see if it's getting power and ground or not. Also, like Mike said, test ALL fuses in EVERY fuse box in the car before taking stuff apart. And it never hurts to try disconnecting the battery for a few minutes, then reconnecting it. Sometimes these things do come back to life with a power reset.