Wiring a relay with internal diode
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=14670
Printed Date: July 19, 2025 at 3:25 PM
Topic: Wiring a relay with internal diode
Posted By: GUIDO401
Subject: Wiring a relay with internal diode
Date Posted: June 09, 2003 at 3:45 PM
I've read several posts but still don't quite understand. The relay I have is to be used to control my electric fan. It is a NAPA Echlin model AR274. Can someone please explain in SIMPLE terms how to wire this. I will have a toggle switch located under the dash for on/off. The relay shows the diode between -85 and +86. Can you tell me what wire goes to -85, which to +86, what wire to 87, 87 and 30. Please keep it simple. I already have a headache. THANKS.
Replies:
Posted By: Velocity Motors
Date Posted: June 09, 2003 at 3:58 PM
Is the fan a (-) trigger on or a (+) trigger on through the toggle switch ? ------------- Jeff
Velocity Custom Home Theater
Mobile Audio/Video Specialist
Morden, Manitoba CANADA
Posted By: GUIDO401
Date Posted: June 09, 2003 at 4:21 PM
Jeff I don't know what you mean by that. I haven't installed the switch yet. Please excuse my ignorance. Can you give me a step by step way to wire this? Thanks.
Posted By: Velocity Motors
Date Posted: June 09, 2003 at 4:39 PM
Depending on the wire that will turn on the fan motor for you ( read the instructions ) to see if the fan will turn on by a negative trigger or if it requires a (+) trigger to turn on. Depending on the type of trigger you will use either a (+) or a (-) relay system. ------------- Jeff
Velocity Custom Home Theater
Mobile Audio/Video Specialist
Morden, Manitoba CANADA
Posted By: GUIDO401
Date Posted: June 09, 2003 at 6:31 PM
OK the fan instructions said to reverse the polarity for the puller fan I am using. So the motor will have the POSITIVE wire to ground and NEGATIVE to the fuse block. So I guess it would be called (-) trigger. This wire would go from the fuse block to the switch. Then from the other switch terminal to the -85 terminal on the relay??? Would the wiring then continue from #+86 to the fan motor? Then what wires to the 2 #87 terminals and to the #30 terminal
Posted By: Velocity Motors
Date Posted: June 11, 2003 at 11:05 AM
IF the system is a (-) trigger you need to wire up the relay like this: Negative to Negative Relay Diagram this willl send a low level (-) signal from the toggle switch to the relay & the relay will convert the low level to a high level (-) signal. ------------- Jeff
Velocity Custom Home Theater
Mobile Audio/Video Specialist
Morden, Manitoba CANADA
Posted By: GUIDO401
Date Posted: June 11, 2003 at 11:12 AM
Thanks for the input. I got it wired and it's working great.
Posted By: Velocity Motors
Date Posted: June 11, 2003 at 11:23 AM
Awesome. Glad I could help.
-------------
Jeff
Velocity Custom Home Theater
Mobile Audio/Video Specialist
Morden, Manitoba CANADA
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