starter kill relay
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=98624
Printed Date: May 10, 2025 at 9:37 AM
Topic: starter kill relay
Posted By: Lubrano
Subject: starter kill relay
Date Posted: November 04, 2007 at 4:32 PM
Could someone please tell me the reason why a diode is installed in a starter kill relay and is it necessary to install the diode.
Thank You
Replies:
Posted By: techman93
Date Posted: November 04, 2007 at 7:11 PM
When energizing the coil of a relay, polarity of the coil does not matter unless there is a diode across the coil. If a diode is not present, you may attach positive voltage to either terminal of the coil and negative voltage to the other, otherwise you must connect positive to the side of the coil that the cathode side (side with stripe) of the diode is connected and negative to side of the coil that the anode side of the diode is connected.
Diodes are most often used across the coil to provide a path for current when the current path to the relay is interrupted (i.e. switched off, coil no longer energized). This allows the coil field to collapse without the voltage spike that would otherwise be generated. The diode protects switch or relay contacts and other circuits that may be sensitive to voltage spikes. (JimR, contributor, install bay member)
Posted By: Lubrano
Date Posted: November 04, 2007 at 7:37 PM
Thank You for the excellent information. My next question adter reading your post is what are we protecting using a diode form a voltage spike in a starter kill realy. Doesn't that wire go to the starter coil?
Posted By: techman93
Date Posted: November 04, 2007 at 8:32 PM
The diode protects switch or relay contacts and other circuits that may be sensitive to voltage spikes.
Posted By: KPierson
Date Posted: November 04, 2007 at 8:53 PM
The diode doesn't protect anything on the contact side (where the starter wires are connected). The diode protects whatever is energizing the coil - in the case of starter kill this would be the ground when armed wire and the ignition feed. ------------- Kevin Pierson
Posted By: techman93
Date Posted: November 05, 2007 at 6:34 AM
The info I posted came directly from this website. https://www.the12volt.com/relays/relays.asp
Maybe you may want to give feedback to have them change their information.
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