Rear Review Defroster

Most rear defrost circuits draw a LARGE amount of current ( about 30 amps in some vehicles ) so a relay is needed to convert the trigger wire to a larger current power source. You will need to get to the back of the switch where the RD is and probe the wires. When you find the wire that activates 12 volts when the RD is pressed attach the a relay to the RD wire.

How did you want to actiavte the RD ? With an AUX channel or with the ACC wire ?

I want to activate the rear defroster when the remote start of the alarm starts the car and deactivate it when I get into my car to step on the gas peddle.  So basically I want to connect it to the same wire that starts the parking lights and starter of my car.  Would that be the ACC wire then?  Hooking it up to an AUX channel would be a alternative choice, but I just want to deactivate it all with one switch.  Also I should use a 30 amp fuse on the power lead to the relay, right?  How about wire gauges?  Would I need to use 12 gauge or 16 gauge is good enough?

Use a 5 pin 30/40 amp relay in this configuration:

• 86 & 87 : 12 volts constant ( battery connection is recommended )
• 85 : GROUND OUT WHEN RUNNING WIRE on RS unit
• 30 : Goes out to Rear Defrost wire
• 87a : NOT USED

Using at least 12 - 14 guage wire is recommended for this connection for pin 30, 86 & 87. An d use a 20 or 30 amp fuse on the power wire on 86 & 87 as well as a 20 amp on the output pin ( 30 ).

I agree with Karl.  Test the wires at the defroster switch, and look for one that puts out a negative pulse every time the button is pushed. 

If your remote starter has a "pulse after starting" output (or something similar), you should be able to attach it directly to the car, and it should activate the defroster.