Hidden connection

[voganni]

Has anyone ever experienced a loss of power to the big white wire at the underhood fusebox that feeds the cooling fan(s)? This happened to me and I was tearing my hair out trying to figure out how a wire that ran from the battery (100 amp fuselink) to the fusebox could be dead. I started unwrapping electrical tape and following the wire inside the loom. Just past the y, about 8" below the battery, there is a factory splice. It joins the alternator main wire to the white wires from the battery, AND the wire to the fusebox. My connection was completely, hopelessly corroded, and the wire to the fusebox had rotted off. After cutting, cleaning, and adding a big copper splice piece, I now have cooling fans! The splice is completely hidden inside the loom. A failure here could also cause alternator issues, although not in my case.

[REN69]

wow... good to know.

[RED91SR5]

I figured this out the hard way too but mine caused alternator issues that made me think it was bad when it wasn't.

[freakinbox]

So basically I should feel lucky my fans won't shut off rather than not work at all? Bloody 20 year old wiring (no it's not the sensors I tried replacing them lol)

[voganni]

I discovered the fans are designed to fail on. The fan relay must be energised to keep the fans OFF. So if the relay (fan #1 in fusebox) burns out, the fan will be on all the time. The ground circuit that turns on the fans is thru the air conditioning high pressure switch, then thru the temp sensor (the one that sticks out sideways with one light green wire). So if the a/c switch opens (too high or too low pressure, not sure which) the fans will also be on all the time. The temp sensor OPENS the ground circuit, de-energising the relay, to turn the fan ON. Your relay should feel warm when the fans are off, as it is energised. If you unplug the relay, the fans should stop. If so, you have a bad relay, open a/c switch, or bad temp sensor. Hope this helps!