terminals 85 and 86

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=120810
Printed Date: July 21, 2025 at 11:30 PM

Topic: terminals 85 and 86

Posted By: larryc
Subject: terminals 85 and 86
Date Posted: March 19, 2010 at 8:45 AM

Is it ok to replace a relay that has terminals 85 and 86 (coil) reversed?

Hyundai 01 Elantra (part number Omron 95224-29000)

A dealership gave me a new relay with slightly different numbers and 85 and 86 are reversed.

Would this damage the electrical system to use it?

Thanks

Replies:

Posted By: howie ll
Date Posted: March 19, 2010 at 9:10 AM

No provided it doesn't have a built in diode.

Posted By: oldspark
Date Posted: March 19, 2010 at 9:10 AM

Except for diodes, they are equivalent.

If spark-quenching/suppression diodes are fitted, the convention is that #86 is the +ve and #85 the -ve side of the relay's coil.
If reversed, the diode will short +12V to gnd until the diode blows, else the feeding circuit or fuse blows.

If it's a snubber/quenching resistor rather than a diode, then it won't matter - they are non-polar like the coil.

A relay should indicate a diode or resistor (rectangle) if they are included internally.

Posted By: larryc
Date Posted: March 19, 2010 at 11:36 AM

The relay is "rectangular" but not marked as to whether it has a diode.

Is there a way to test it for a diode?

thanks

Posted By: oldspark
Date Posted: March 19, 2010 at 4:28 PM

It's tricky - a voltage divider is probably best...
IE - if connected with a resistor of similar value (to the coil - probably between ~80 to ~200 Ohms) and place across 12V, in one direction the diode will short the coil hence reducing the coil's voltage to about 0.6 volts, or conversely, brightening the bulb if a test lamp is used - ie, a 3W bulb is about 60 Ohms.

But relays with diodes should be marked...

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