ECU, Wiring, Sensors
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By 1-low-92-EG-Sedan
#350714 ok so i have a 92 sedan with a remote start and want to wire up the rear defrost to go on with the remote start im not really sure on how to go about wiring it all up..there is a negative trigger wire from the remote start module ..but i have no idea what wire to tap into from the defrost switch(or if i should even tap into it there) im also not sure if i need a relay to make the trigger wire a positive instead of a negative .. any help would be greatly appreciated thanks in advance :thumb: :thumb:
Last edited by 1-low-92-EG-Sedan on Fri Jan 09, 2015 3:12 am, edited 1 time in total.
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By ExCoupe94
#350774 Your remote starter should have some kind of aux output similar to a trunk release output which is typically a momentary negative pulse, if not u can use the trunk output itself if it's not being used but I'm not sure if that defrost switch outputs a momentary signal or a latched (I think it's momentary in which case u would use said output) or if it's a positive or negative signal (obviously if the switch outputs positive u will use a relay to reverse polarity) however if the switch operates in a latched manner (which I doubt) u could use the "ground while running" output on the remote starter also known as "gwr" or simply "status output" which sends a constant negative signal while the car is running under remote start.
What is the make/model of your alarm/remote starter?
I might run a couple tests if I have time tomorrow at the shop and get more info on the switch itself. No promises though
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By suspendedHatch
#350800 I've done it before but I don't want to risk giving out bad info.

If you can post up the defrost diagram from the helms I'll sort it out for you. I hate scrolling through the PDF to find things. It's such a big file that acrobat stutters like crazy even though my computer is the shiz.

You're going to need a relay. Remote start outputs are almost always in the mA. Relays aint no thing, though.
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By 1-low-92-EG-Sedan
#350915 ok so i ended up figuring it out.

the only way i could figure it out was tapping into the the defrost button wire harness on the dash (blue/yellow wire to be specific) which sends a positive signal to the relay in the under hood fuse box
in this case i actually had an extra accessory wire that actually sends a positive power so all i simply did was connect my second accessory wire to the defrost button on the dash (blue/yellow) with a 15 AMP fuse for extra safety...if you do not have a positive signal wire to use all you have to do is use a relay to revers the polarity
(there may be other ways but with the setup in my car specifically this worked best for me)

now the only down side to setting it up this way is EVERY TIME i use my remote start my rear defrost will be automatically turned on...but in my case its not that bad because i only use my remote start in the winter any ways
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By TrailerTrash
#350918 great addition to a convenient mod :thumb:

i dont see how it always coming on is a bad thing :? youll never have to wonder if its on or actually turn it on when you use the starter. and its not like itll overheat if you use it in the summer
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By ExCoupe94
#350919 sweet! glad u got it figured out! now i didn't get a chance to probe any wires but i noticed while defog is active u can kill the ignition turn it back on but the defog doesnt reactivate with the ignition, telling me that the output signal from the switch itself is momentary not latched. I doubt it will cause any problems... basically holding down the button throughout the entire 15-60 minute remote start sequence just keep an eye out for any adverse effects.
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By 1-low-92-EG-Sedan
#350929
ExCoupe94 wrote:sweet! glad u got it figured out! now i didn't get a chance to probe any wires but i noticed while defog is active u can kill the ignition turn it back on but the defog doesnt reactivate with the ignition, telling me that the output signal from the switch itself is momentary not latched. I doubt it will cause any problems... basically holding down the button throughout the entire 15-60 minute remote start sequence just keep an eye out for any adverse effects.


ive used it 2 times so far and no issues at all...i will actually be able to use it today on lunch considering it actually snowed :thumb: :thumb:
By XtheMex
#350937 Is it convenient to have remote start with manual transmission, do you always leave it in neutral. I've been contemplating about getting remote start + security from viper.
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By suspendedHatch
#350985 Instead of running the accessory wire directly to the defrost wire, run it through a relay controlled by an aux output.

Accessory wire to 85 and 30
Defrost wire to 87
Remote start ground output to 86

Depending on which remote start negative output you use, you'll hit a different button sequence to remote start it. It should be detailed in the alarm's owner's manual.