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relay ground

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=117047
Printed Date: May 12, 2025 at 1:59 PM


Topic: relay ground

Posted By: dadtruck
Subject: relay ground
Date Posted: October 18, 2009 at 9:39 AM

Reworking a 95 Caravan relay box to fit a different application.

in the original the relay wiring is: 30 power in, 87 power out, 85 trigger, 86 ground.,

Question,for the original 95 Caravan wiring ,the 86 relay grounds for the AC Clutch, high rad fan, auto shut down, low rad fan, fuel pump, high rad fan ground relay were all connected to common ground bus bar within the module, Three additional relays, back up lights, trans relay, starter relay were not. These last three the 86 relay grounds ran seperately.

Why would there be seperate 86 ground wires for certain relays, not for others?

I am rewiring this module to make the trans relay and starter relay be the low / high beam relays, Will use the back up light relay as a HEI relay...auto shut down will be a horn relay,, high / low rad fan and ac comp will stay as is.Was planning to make a common 86 relay ground for all the relays, to make the wiring simpler, Is that OK?

thanks



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DadTruck



Replies:

Posted By: howie ll
Date Posted: October 18, 2009 at 10:09 AM
Carefully looking at this, first the normal (ISO) practice is to make 85 the ground. In practice it doesn't matter unless there are onrush (feedback) diodes across the coil terminals. Those 86s that are seperately grounded, those grounds might have gone through neg. sensors e.g. temp switch etc.  Except the ones with the common grounds are the actual ones I'd have separated if you think this through.  Either get out your DMM and check to see that they are grounds, or get a wiring diagramme.


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