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Testing Relays How to

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=71164
Printed Date: July 15, 2025 at 1:14 AM


Topic: Testing Relays How to

Posted By: wendel_600
Subject: Testing Relays How to
Date Posted: January 20, 2006 at 10:42 AM

can anyone tell me how to test a relay.

30-86-85-87-87a

should i have contenuity through the coil



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wendel600



Replies:

Posted By: brcidd
Date Posted: January 20, 2006 at 11:29 AM
Continuity- yes- with a resistance due to the coil- but still doesn't say that the switchable contacts are carrying the current- I have seen many relays energize, and pull in- yet have burnt contacts that will not carry any amp load- they can show voltage- but not load- give them something to do and they choke- easiest thing to do is to swap it with another one- most cars use multiple relays of the same style- so a swap is easy.  In most remote/alarm system- the draw is minimal- so burning contacts may not be an issue- sometimes just hearing/feeling them click is enough to know they work- what is your exact application or concern?

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Brcidd - Engineer That Does Remote Starter Installs on the side.




Posted By: prdjr165
Date Posted: January 20, 2006 at 11:30 AM
put 12volts to term 86
ground term 85 and you should here a click




Posted By: dualsport
Date Posted: January 21, 2006 at 3:40 AM
If it's a standard high current relay, connect 12V to term 30, and put a test light or maybe an old headlamp between term 87A and ground. It should light up, which checks the normally closed contact path.

Then connect 12V power between term 85 and 86 to energize the coil, and you should see the test light go out. Connect the test light between term 87 and ground, and it should light, checking out the normally open contact.

You could also measure continuity with a DMM instead of using a test light. If you don't read a dead short, the contacts may be pitted or burnt, as brcidd mentioned, and it may not work properly for high current applications.





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