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Bad Relay?

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=25254
Printed Date: July 17, 2025 at 4:04 AM


Topic: Bad Relay?

Posted By: Crane14
Subject: Bad Relay?
Date Posted: January 25, 2004 at 1:25 PM

Hi There, I have a 2000 Tahoe and no longer have use of  the rear windows, driver side door lock or power mirrors. I checked all the fuse blocks and can't find anything blown, any ideas?? Thanks



Replies:

Posted By: Teken
Date Posted: January 25, 2004 at 2:18 PM
Crane14 wrote:

Hi There, I have a 2000 Tahoe and no longer have use of  the rear windows, driver side door lock or power mirrors. I checked all the fuse blocks and can't find anything blown, any ideas?? Thanks


1. Have you made any modifications recently to the vehicle?

2. How did you varify the fuse(s) in the vehicle?


If you still suspect the relay(s) as being the culprit. Locate the relays and measure first the coil side of the relay. It should measure from 80-120 ohms from pin 85 & 86.

Then measure the contacts, of 30, 87 & 87a. With pin 30 connected to your DMM with a clip, you will probe pin 87a and it should measure 0.0 ohms.

Moving your probe to the 87 position should show a open or infinite measurement.

All of the measurements, are of course using the resistance mode, and with the relay disconnected from any power source.

The next step, is to make your measurements with voltage, to ensure that the contacts, and coil are ineed sound.

Normally, if you hear a click from the relay, it will tell you it is fine. But this does not mean it is fully functional, only that it does activate.

Upon the 1000 set, and reset of the relay you will see that there is a *make contact* differential in the coil, and the contacts of 30 & 87, 87a

So please keep that in mind.

Regards

EVIL Teken . . .





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