adding defrost to RS for sunfire

Printed From: the12volt.com
Forum Name: Car Security and Convenience
Forum Discription: Car Alarms, Keyless Entries, Remote Starters, Immobilizer Bypasses, Sensors, Door Locks, Window Modules, Heated Mirrors, Heated Seats, etc.
URL: https://www.the12volt.com/installbay/forum_posts.asp?tid=42654
Printed Date: September 12, 2025 at 5:19 AM

Topic: adding defrost to RS for sunfire

Posted By: ngooo
Subject: adding defrost to RS for sunfire
Date Posted: November 10, 2004 at 7:17 AM

Hi Everyone,

This is a great site, and thanks to many people on this forum, i was able to install a prostart starter on my 2000 sunfire this past weekend.

i do require some more help, i have a third channel trunk output that i am not using and would like to dedicate it to the rear defrost if possible.

the RS wire is a 500mA negative output (1 sec pulse), operates only when ignition is OFF or when the vehicle is running under remote control.

anybody know what wire at the switch should i tap into? will i need to add relay circuit?

thank you.

Replies:

Posted By: MJA1962
Date Posted: November 13, 2004 at 10:34 PM

If you are able to access boths sides of the Defroster switch and make connections to the terminals in parallel, you can try something like this, using a relay:

Pin 85 - Constant +12V

Pin 86 - Negative pulse from trunk output

Pin 87 - One side of Defroster switch

Pin 30 - Other side of Defroster switch

Here is some information regarding relays: https://www.the12volt.com/relays/relays.asp

-Michael

Posted By: TJ92Civic
Date Posted: November 13, 2004 at 11:11 PM

https://www.velocitymotorsport.com/images/install_notes/106.jpg Check that out. Good luck!

tim