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Reversing polarity

Printed From: the12volt.com
Forum Name: Relays
Forum Discription: Relay Diagrams, SPDT Relays, SPST Relays, DPDT Relays, Latching Relays, etc.
URL: https://www.the12volt.com/installbay/forum_posts.asp?tid=4166
Printed Date: July 22, 2025 at 11:29 PM


Topic: Reversing polarity

Posted By: tikech
Subject: Reversing polarity
Date Posted: October 03, 2002 at 10:39 PM

Ok, here’s what I would like to do. When I turn off the ignition I would like to send a negative pulse to BCM’s illuminated entry input, so that when I turn off the ignition the courtesy lights come on. I have thought of a way that might work. When I turn off the ignition my crimestopper 2003DC sends a positive pulse to the door unlock relay. If I tap in to that wire and use a relay to produce a negative pulse, I could then use that to activate the illuminated entry system. Is there a set up of relays that I could use to accomplish this? I have searched this site but haven’t found this exact set up. Also if you know a better way to accomplish this please let me know. I have a 1996 Dodge Intrepid.  Thanks.



Replies:

Posted By: the12volt
Date Posted: October 04, 2002 at 10:05 AM

If you just want to convert a positive pulsed output to a negative output, wire an SPDT relay as follows:

85 to positive pulse output from alarm
86 to ground
87 to ground
30 = negative pulse output
87a (not used)

If your ignition lead shows continuity to ground when the key is turned to the off position, you can use the following diagram: https://www.the12volt.com/doorlocks/page3.asp#aul to send a negative pulse to the BCM instead of the "unlock circuit" as shown.

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the12volt


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