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Isolating 2 Negative Input Triggers

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=147199
Printed Date: March 29, 2024 at 12:54 AM


Topic: Isolating 2 Negative Input Triggers

Posted By: tctctc
Subject: Isolating 2 Negative Input Triggers
Date Posted: December 31, 2021 at 9:07 PM

Wiring up electric fans integrating trinary switch and Holley efi - both having negative triggers to activate relay. Need one of the fans to kick on from trinary switch with ac on without feeding signal back to efi ecu, as well being able to kick in fan based on temperature using ground trigger, preferably without feeding signal to trinary switch.

I currently have relay wired up as follows -

30 - 12v constant
87- fan power wire
85 - 12v ignition
86- efi ecu/trinary switch outputs (both ground signal)

Tried using diodes (1N4007 DO-41 ) on both wires from ecu assuming diodes would work with keeping flow in one direction on ground signal vs 12v but doesn’t appear to be the case.

Anybody have a simple/straight solution you can recommend? Really don’t want to switch my relay input triggers to 12v if I don’t have to, only because I’m assuming the trinary switch may not play nice with 12v going to it, however I could be wrong.

Open to any recommendations. Thanks in advance!



Replies:

Posted By: Ween
Date Posted: January 01, 2022 at 1:54 PM
Banded end of diode connects to the negative trigger/input. Non-banded ends connect to load (relay coil).




Posted By: i am an idiot
Date Posted: January 02, 2022 at 7:50 AM
Do not worry about the 12v on the trinary switch. If it is a negative output, it has to be able to accommodate positive voltage on it until it puts ground there.

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Let's Go Brandon Brown. Congratulations on your first Xfinity Series Win. LGBFJB





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