how do i check for a relay draw?
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=21154
Printed Date: July 12, 2025 at 3:10 PM
Topic: how do i check for a relay draw?
Posted By: rye2
Subject: how do i check for a relay draw?
Date Posted: November 08, 2003 at 10:15 AM
hi,
I'm interested to know how would I check to see if a SPST automotive relay is drawing current when the car is off? I have alwasys had trouble in this area.
I need some help, how do you measure it usinc a DMM and if someone could explain where the leads go and on what pins etc.....
I don't want to end up having a circuit that will have a draw that will eventually kill my battery...
Thanks.....
i'll be using a 5 pin relay, pins 85, 86, 87, 87a, 30.
Replies:
Posted By: auex
Date Posted: November 08, 2003 at 10:32 AM
As long as the relay isn't energized at all times then there shouldn't be any draw. This means that if you are worried about it causing a draw hook up the relay to turn off with either an ignition or accessory wire.
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Posted By: rye2
Date Posted: November 08, 2003 at 10:42 AM
Oh, ok i'll keep that in mind....Thanks
Posted By: jrinbc
Date Posted: November 08, 2003 at 1:06 PM
I assume you are interested in knowing if it is drawing across the coil (pins 85,86). If so, set your dmm for dc current. A coil normally draws less than 200mA so set your DMM accordingly. Current is measured in series so disconnect one of the coil pins (I use 85) connect the neg probe of your DMM to the wire you just disconnected. The pos probe goes to the pin on the relay. That's it. Good luck.
Posted By: rye2
Date Posted: November 08, 2003 at 2:56 PM
thanks, this is great information
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