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

(1997 Mitsubishi Galant)
in Redlands, CA on October 12, 2013
When I hit the button on the dash it lights up but no power to the grid. I checked with Mits and they can't ID the wiring/ fuse or location of the relay connection to the window itself. On my model there are NO visible connectors from the C pillar to the rear window grid, so I have no clue about where to start.

Had the radio replaced 6 months and also replaced the power antenna by so-called professionals. Both are not working properly and the installers will not fix the probs without more money. Now the defroster is toast! So do you think this is related? Again, I can't get Mitsubishi to find the information for my defroster! If anyone has the answer, then HIT ME UP!
Displaying 1 answers & 6 comments
Popular Answer
on October 13, 2013
Sounds like they tapped into the grid circuit and used it for the accessory power supply source. Try disconnecting the audio unit and see if the grid warms up. If they also installed speakers in the rear package shelf, they may have nicked a portion of the grid and broken the circuit. This can usually be seen as a gap in the stripe on the window. If this is the case, there is a repair kit for these. Or you may want them to pay for a new window. Just make sure they don't install it!
on October 13, 2013
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??
on October 13, 2013
Have you tried to operate the defroster with the audio system turned off?
on October 15, 2013
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!
on October 15, 2013
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
on October 16, 2013
Thanks for the input! I think you are correct in your assessment and know that leads to a bigger issue which I related earlier... How do I find a person who knows what they are doing? I've tried the local mits dealer (clueless) who referred me to the people who jacked me up in the first place. And as I've stated I went to three others who all were too lazy or ignorant to fix the error.

Now that it appears they spliced into the defroster wire, what would you suggest I do? If anyone reading this has FIRST-HAND, PERSONAL experience with an expert who can fix this - Hit me up!

on October 16, 2013
Well, do you feel like a road trip to the Texas panhandle? I wouldn't plan a vacation here but I bet I could fix your car. No seriously, you might have some luck if you run a local search on Angie' At least you won't be taking a stab in the dark. Luck to you; good ones are hard to find.
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