'04 rancher 400at fan problems

Yep - sounds like the oil temp sensor is either bad or doesn't have a good connection. As Helmut mentioned, check the temp sensor to verify that it is working properly.

There are some other threads here that have some detailed information. Here's one from Helmut on this very subject.

Melsman

So, are you saying that the temp light is on, but the fan is not running? Or are you saying the engine stalls, and the temp light is NOT on and the fan is NOT running?

If the temp light is on, but the fan isn't running - and the fan checks out (as you said previously it does) - then there are only four other items in the circuit - a 15 amp fuse, the electrical connectors, the oil temp sensor, and the ECU.

I'd check the fuse first, then the connectors. If that doesn't do it, then replace the temp sensor. And if that doesn't work, then you could be looking at a faulty ECU.

Melsman