Ok. This is strange. I have been working to fix my "service 4wd" light issue for over a month. Today I started testing the wire harness at the TCCM for continuity. When I connected the light green with black tracer and the purple with white tracer (I believe these are for the speed sensor), I heard a loud hissing sound (like a high pressure line suddenly released pressure) and a white fog began to come out from under the passenger area under the vehicle near the firewall. I turned off the vehicle and restarted it. No issues until I reconnected the wires and it happened again. My A/C was no longer cold. I gathered that the hissing and fog is emitting from the A/C drier, evap core area. It confuses me because I have never had an issue with my A/C and did not believe the two could possible be connected in any way. However, I believe the wires are bound together somewhere and the wire for the 4wd is next to the A/C wire and they are rubbing together which caused an open in the wires? Is there a safety release valve that is controlled electronically which would activate is there was a short of some sort? This has me baffled. Any help will be appreciated.