What is this relay for?

[Joeairforce]

I'm surprised your Sub doesn't have one.

Mine didn't even have anything resembling a computer in it until last week.... lol.... Must have been a gasser thing.....

 

[Bagged Dually]

I'm not sure I've ever heard the electric fan kick on even with the AC on. That red wire that's been cut looks like it could be long enough to reach the distribution block on the fire wall. I'll try connecting it there in the morning and see if the fan kicks on at all. When I got this truck they had all kind of weird things wired into it and the AC wires had been cut at the pressure switch. Not sure why. I hooked them back up and the AC works like a champ. I'll let you guys know if that's for the fan in the morning. Thanks for the help guys.

 

[bucket]

My '86 454 Burb has the electric cooling fan, it comes on when the motor starts to get hot (only been hot enough once though). AC is inop though, so I don't know if it comes on then too. I'm curious if I have that relay now.

 

[Manbearpig]

Well that's news to me... Never seen that before...

Same

 

[Bagged Dually]

Well I hooked the wire up to the dist. block yesterday and with it running and with the AC on it never did kick the fan on. Than it again I'm sure the truck never reached any temperature near needing an extra fan to kick on. I'm just going to leave it hooked up like it is and we'll see what happens.

 

[RetroC10Sport]

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[RetroC10Sport]

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You can see the relay in this '88...

 

[Bagged Dually]

I still haven't been able to 100% for sure figure out what it does. I'm still just assuming it's for the fan. Hopefully it doesn't come back to haunt me...

 

[crazy4offroad]

Find the temperature switch that ties controls the e-fan, unplug it and ground the wire. Then if the relay is for the fan, the relay should click when you plug/unplug it.

 

[Jims86]

Find the temperature switch that ties controls the e-fan, unplug it and ground the wire. Then if the relay is for the fan, the relay should click when you plug/unplug it.

Tell me what the wire colors are that are going into it, and I may be able to trace it down. some of those had wide open throttle A/C cutoff relays. fuel pump relay would have a red/wht,grn/white, and a larger gauge orange wire, and grey wire...usually mounted more to the Port side of center on the firewall.

 

[Bagged Dually]

The cut wire is a heavy gauge solid red wire. There's another heavy gauge Black wire with a red stripe. The other 2 wires are a smaller gauge. One of them is solid green and the other is white or white with a pink stripe(To dirty to tell for sure). Only the heavier red wire is cut and the rest seem to still be connected.
I'll try the grounding the temp switch tomorrow and see what happens. It's already dark and raining here right now. I get to put a new Master Cylinder on the beast in the morning anyway so I'll try it after I get done with that.
Thanks for the help guys. I really don't know if this relay will ever affect anything, but it's just going to be one of those little things that drive me crazy until I figure it out now.

 

[Joeairforce]

but it's just going to be one of those little things that drive me crazy until I figure it out now.

I know how that is....

 

[crazy4offroad]

I looked in my crappy Haynes manual and for 6-cylinder engine compartment it shows a "speed switch relay" and it's listed as "For H4D Only". It has a white wire, black wire, yellow and a pink with black stripe. Not sure what a relay like that would control, other than limit top speed. But that's all I could find as far as relays under the hood. IMO since the one you're dealing with has a solid green (dark green?) I believe it's for the fan, since most temperature switches use the green wire. It's possible it may never kick on if the temperature switch is bad, which is why grounding it will tell you what it does (or doesn't do lol) While you ground it have someone watch your temperature gauge and if the needle pegs hot it the one you're messing with is the wrong one, may have to look around on the motor and see if there's another one.

 

[Bagged Dually]

Well while putting my headers on today I grounded out the temp sender that's in the right side head and the relay clicked. I did it several times and it kept clicking but the fan never came to life. I'm guessing after years without use the fan probably just locked up. Anyway I guess myself and anyone else wondering knows 100% for sure what it does now.