goodtyms

I have the under bed mounted aux trans cooler that the previous owner cut the wires from the temp switch and replaced it with a straight wire. I'm assuming that he did this because the fan wasn't working - I've never seen or heard the fan come on, even at the top of a pass.

A few questions:

First of all, does the switch/sensor that's mounted in the cooler make the connection between the two attached wires, completing the fan circuit, or is one wire connected to ground, the other connected to a relay? Would jumping the swith/sensor make the fan stay on all the time?

Also, is there also a toggle or rocker switch that enables the aux cooler? I have and extra toggle switch that I'm not sure of the function. Where is the aux. fan relay located?

wannadiesel

That cooler was a dealer installed option, my '93 FSM has no info on it.

That said, I'd imagine that jumping the switch will turn the fan on. It sounds like you need to spend some quality time with a 12v test light.

The cooler should be automaitc, but who knows what a PO might have done. Perhaps the thermo switch failed, or it kicked in at a higher temp than the guy wanted to see.

bigragu

I have the factory installed fan. There is no relay. Hot off the battery to the fan t-stat with a fuse in between. The t-stat is therefore hot on one leg from the battery, from there the other wire from the stat goes to the fan, 2nd wire at fan to ground. For the 1st year of ownership, mine never came on either and just yeterday the tranny temp guage got up to 195...no auto on still. A year ago I tied in a manual toggle switch with a built in "on" led light, so I flipped that fan on manually yesterday and within 20 minutes it dropped from the 195 degrees to 178 degrees. I suggest you wire in a switch. Nice feature.