Anyone recognize this relay?

[myraley]

Hi Guys. Can anyone tell me what this relay (off the firewall of my 72 GMC Jimmy) is? It was above the fuse panel on the drivers side. It has 4 prongs, and one is cut out in the center. And not connected to anything, but everything works. But so much wiring has been replaced, it coulda been to anything. Any ideas? I'm gonna try to attach three photos, lets see if it works. Thanks!
Eric

 

[dremu]

Well, could be anything. Be nice to know where the wires go -- and yeah, some of them go to the battery =))

I'm inclined to suspect a battery isolator / dual battery hookup, but I donno so much about gen-1 trucks.

-- A

 

[4X4HIGH]

I really have no idea but maybe a horn relay?

 

[ryoken]

I really have no idea but maybe a horn relay?

that would be my guess....

 

[longbedder]

That looks a little bit similar to the heater blower motor relay on truck I had, but the location on that was passenger side.

 

[Mike D]

I looks like a heater fan relay on AC equiped vehicles. This is usually mounted near the heater motor. Open it up carefully and trace the contacts.

 

[myraley]

I would like the horn relay idea, except that I have working horns. And a working heater blower, too. I think the horn is three prong, not four, but I will look and see. It looks like its been there since the truck was made, or I would think it was added on as some aftermarket thing. So no one has one of these up high on the inside of the firewall in their truck?

 

[Cowboy_80]

I would like the horn relay idea, except that I have working horns. And a working heater blower, too. I think the horn is three prong, not four, but I will look and see. It looks like its been there since the truck was made, or I would think it was added on as some aftermarket thing. So no one has one of these up high on the inside of the firewall in their truck?

Looks like a relay to me, as for what, that's just a game for speculation. You have a horn, you have a heater, but that doesn't mean that one or the other didn't use that relay before someone started their own rats nest. Heck, it could have been for an additional horn that has since been taken out. But a relay, to be a relay, has to have four prongs. Two for the switch, and two for the load. Granted, the case could be used as a ground, but that would be a pain for troubleshooting and circuit isolation.

 

[bigblock72]

That is definitely the original horn relay. Someone has added/changed the relay at some point in the last 35 years.