SBC + Taurus fan wiring

Joined
Nov 2, 2004
Messages
336
Location
Boulder, CO
3 way switch, 1 lead to each relay (one for each speed). I'm not wiring this to the ignition so the fan will work when the key is not turned. I have 4 connectors to the relay, and I'm not using any thermostat right now. I've got a ground, hot lead from the battery, lead from the switch, and then the fan connected. I cannot get the switch to turn the fan. However, when I pull the power wire to the fan it runs. Both speeds work fine that way, just not with the switch.

I've got to be doing something wrong here. I checked some pirate wiring diagrams and well as some on here and can't get it to work with those configurations. I was told by the guy at the parts store that on the relay, 85 was for the toggle, 86 for the ground, 87 for the fan, and 30 was the hot lead to the battery. Do I have the wrong relays maybe?

There are 3 prongs on the switch, but one is labeled off, so I'm assuming that I don't need to ground at the switch. Any help is greatly appreciated!!!
 

Bret

 
 
Joined
Oct 31, 2003
Messages
2,310
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MT
From what it sounds you should have power going to the center blade on your toggle switch if it is a SPDT (single pole double throw) then you would have a wire go from the other two posts to high and low respectively. You can verify your switch with a meter if you have one, or there may be a small diagram on the side. That will provide the power to your relays to energize. Your relays should have constant power (fused) on 30 and ground should be on 85. switch power should be post 86. Power going to your fan will come off 87/87A. This is provided you are using a normal 12V 30A relay. Your fan should also be grounded IIRC.
 
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Joined
Nov 2, 2004
Messages
336
Location
Boulder, CO
Hey Bret, I think you nailed it. I have not yet had another chance since I posted to work on this issue. However, what you're saying makes perfect. I'm gonna have at it tomorrow again and I think I'll be able to get this knocked out tomorrow. Thanks again for your advice, I think you're right on.

Oh, one other thing... if I'm providing the switch itself with power, where does it ground to, or does it not need to ground to anything since both relays + fan are already grounded?
 

Bret

 
 
Joined
Oct 31, 2003
Messages
2,310
Location
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Unless the switch is lighted, you don't ground the switch. It just passes power to your accessory.
 
Joined
Nov 2, 2004
Messages
336
Location
Boulder, CO
Switch isn't lighted. It all makes sense now. We got the truck back in action today with everything working. That Taurus fan really pulls a lot of air, and I think the SBC will be happy now. Time to go wheelin! Thanks again Bret.
 
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