My rear defroster will not function after Audio install - Mits has no clue

Thanks for the info but since I did not install the audio and don't know which wire is for what system, I have to find someone to do the repair for me. Without Mits giving any guidelines or wiring spec, I don't have any option. For that matter does anyone here know of a honest guy who could repair my issue and is close to Redlands, CA??

Have you tried to operate the defroster with the audio system turned off?

Yes I have! No difference - the defroster gets no power. Now here's the funny part in regard to the Audio.. I activate the audio and can hear the electrical hum from the defroster/ AC and even the engine. And three different audio places say everything is 'FINE?!?' I think they jacked up my wiring and now I REALLY need an expert on this as I am not one! HELP!

I would have to agree with you. Some late model cars have as many as 12 separate computers for everything from the audio system to the seat controls to the power windows and even the dome lights. They are linked together with twisted pairs of wire for communication purposes on a LAN or local area network. This requires a great deal of wiring to achieve and here's the problem: the installer needed one wire that was hot with the key in the accessory position and in run for main power and one that was hot all the time for the audio unit memory for things like radio presets and the clock. Many of the wires in the dash fit the bill but an installer has to discriminate. I think what has happened is they tapped the power wire for the defroster ahead or upstream of the load (the grid in this case). Now, if you think about a water hose turned up high to a sprinkler--what happens if you cut a hole in the side of the hose? The sprinkler doesn't spray as high and depending on the hole, it may not work at all. Same thing with the defroster, more or less, except they didn't just cut a hole, they added another load-the radio-and it is taking to much of the power that was originally designated for the defroster grid. The grid needs a good solid power source because it's basically a long wire that is intentionally shorted like the old space heaters with the glowing element inside. If it's only getting say 9 of the 12 volts for which it was designed, it is not going to function. Either take it back and make them fix it for free or call someone new to find another power source for the radio. Good luck