2004 Jeep Grand Cherokee Electrical

Several attempts have failed to fix several issues.

When attempting to operate master control switch in driver door, and when shifting, power is interrupted to the radio. Switch also does not operate locks or windows, but clicks in all doors, and lights in switch flicker. Right directional also kills radio and clicks in door. Wires in door boot have been checked and fixed all the way around the jeep. I have been able to put the windows up by applying outside power to the (disconnected) plug inside all doors. Overhead display is not working, and neither is the speedometer/odometer. All other gauges seem to be fine. Also, there is no power to the rear defogger, wiper or window latch. Found and hopefully fixed a back feed from the directional/headlight lever on steering column that drained battery, and was making the tail lights flicker when the car was off, but all other problems persist. Internal wiring harness has been changed to no avail. Diagnostic codes read P1495, P1762. I'm at my wit's (and bank account's) end. I'm not very good at electrical work at all.