Wondering where the fan relay wire (and the relay itself) are located on an 85 Trans Am. The only wire I have disconnected is a tan and white wire that went to a relay on the driver side firewall. Looking up the part number told me that was the fuel pump relay, so I don't think it's that wire. I've been over the schematics, can't seem to find the wire. If I'm unable to find it, I can just run a fused hot wire from the fuse box to an aftermarket relay, right?

 

Fan relay should be on the rad support. Thinking passengers side IIRC.

 

It must have been removed then, no relay on the rad support anywhere, and no wires in that area. I did freshen up all the looms and moved a few wires around for my application, but all of my wires are accounted for. Where does the fan relay wire start? +12v from the fuse box?

 

Pretty sure most of them grab 12v power right off the battery cable.

 

That makes sense, but shouldn't there be a keyed excitation wire?

 

Yep, but I don't have an early Firebird wiring diagram on hand.

 

That's the one I can't seem to find, I didn't see it on the C100 diagram, where does it come through the firewall?

 

It wouldn't be in C100, it'd be in the ECM harness.

 

That makes sense, I removed the ECM and harness when I went to a carb. I'll run a new wire from the fuse box. Thank you!

 

What size and color is the factory wiring, if you happen to know off the top of your head? I'm assuming it doesn't handle much current because it just energizes the relay, but I want to be sure.

 

Pretty sure you'll want to grab a pink w/blk trace, and use that as your 12v keyed, grab a radiator fan switch and wire it into the opposite side of the relay coil for ground. Then run a 12ga or 10ga wire from 12V constant to the fan, and the other wire from the fan to a solid ground. Don't forget to put a fusible link or a good quality fuse (maxi-fuse or better) in the 12v constant. If you want to add a manual switch, T a wire into the fan switch lead, and run it to a switch inside, run the other side of the manual switch to ground... Kind of comes in handy for drive-thrus and unexpected bumper to bumper traffic jams on 100* days.

 

What would be the purpose of the first switch you mentioned? Couldn't I do a 12v keyed, a 12v constant, and a ground wire (and the other wire to the fan)? Why put a switch on the relay ground, to disable it if I'm working on something? Thanks for the tip on the fuses and manual switch, I'll likely do a manual switch while I'm at it.

 

The reason to use a fan switch is so the fan isn't on all the time. It doesn't need to be on until the engine heats up past the normal operating temp, and likely won't ever need to be on at cruising speeds either. A temp activated on/off switch only kicks the fan on when the engine is hot enough to need it.

 

I missed what you meant by switch, I have one. That should do it, I'll probably wire it all up today. Thank you very much!

 

Wired it all up and it looks/ works great. Thanks for the help!

 

Well done!