[the roadie]

The sensor is built into the fan clutch. Many threads here on replacing fan clutches.

 

[the roadie]

then u mean i must replace the fan clutch ?

Usually, yes. But some members, perhaps one or two over the years that I've been a member, have found problems in the wiring harness. But in almost all cases of problems with 2002-2004 fan clutches, and you have a 2002, the failure rate is very high, I concluded you were in a location with high ambient temperatures and you might as well change it out. At least that is my non-professional opinion.

no way to fix this sensor ? like this toipc Wiring problem ?

Perhaps. If you're going to fix it yourself - YOU need to go look at your wiring and come to a conclusion. We're just an Internet forum. We can't see your vehicle. Our advice is free, comes with a lot of experience, but cannot be guaranteed.

now it is working but stopping some times , then i disconnect the battery for 20 min the it work !

Well good. That means it's an intermittent problem, the worst kind to solve. Because then you can't be guaranteed to find the problem with a meter. You might find wiring problems with a visual inspection. But maybe not. How muuch time and trouble do you want to go through before just putting a little money into the repair?

the dealer say i must replace the thermostat also beacuse the down hose colder than the upper hose

What does your temperature gauge read? Have you ever had a temperature-related code? Your dealer may know best. Our advice cannot always be superior to theirs.

and replace the engine sponsors ( engine chairs )

These are usually called the engine mounts. Very rare failure on trailvoys. Does your engine sag or vibrate more than before? You may have to trust your dealer's advice on this. But thanks for the reminder - I may have to go check my own engine mounts for sagging because of the abuse I give it.