simple diode and alarm question

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=16439
Printed Date: July 15, 2025 at 11:19 PM

Topic: simple diode and alarm question

Posted By: cpgoose
Subject: simple diode and alarm question
Date Posted: July 18, 2003 at 7:46 PM

Here's a simple one that I just want to make sure of before I do the install. My friend already has a basic alarm in his car. We added a bulldog rs82 remote starter (very basic). I have to install the hoodpin switch to the remote starter, but I also want to piggyback it onto one of the alarm's wires so the hood is also a "sector", so to speak. Previously, the alarm didn't cover the hood. Basically, I want to know, if I install the hoodpin to the remote start, and then piggyback it to the alarm, which way should I face the diode?

Thanks!

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Replies:

Posted By: the12volt
Date Posted: July 18, 2003 at 8:21 PM

Hi cpgoose, connect the cathode sides (stripe) of two diodes towards the hood pin. Connect the anode side of one to the remote start and the anode side of the other to the alarm.

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Posted By: JWorm
Date Posted: July 18, 2003 at 11:07 PM

You really don't even need to use diodes. There won't be any feedback issues. But what was posted above would be correct.

Posted By: cpgoose
Date Posted: July 19, 2003 at 11:45 AM

hey, thanks for the replies! I didn't realize that I would need two...but ok :-) Can I just confirm what this is doing? The two diodes are preventing feedback from the hoodpin to the alarm and the remote starter?

Here's a picture to make sure I got what you're saying:

https://www.angelfire.com/nj4/cpgoose/hoodpin.html

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Posted By: the12volt
Date Posted: July 19, 2003 at 12:22 PM

That is correct, but since you have the hood pin going to the door trigger in your diagram, I'd add another diode on the door trigger lead (where you have the dot) with the cathode towards the door pin to prevent the interior lights from coming on when the hood is open.

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Posted By: cpgoose
Date Posted: July 21, 2003 at 7:58 AM

Thanks 12volt! I got it to work! I put that 3rd diode on the door trigger wire like you said, but then I made the mistake of putting the wire coming from the hoodpin switch before the diode (in other words, the door side rather than the alarm side of the diode), and the domelight was still coming on when I opened the hood. So then I switched it, and put the wire on the alarm side of the diode, and then it worked. One of these days I'll understand what it's doing posted_image

Thanks for the help!

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