WHERE IS TERMOSTATE ON03 DIAMANTE 3500 - 2003 Mitsubishi Diamante

there is a transmission control module under the dash . it is behind the console.

Here is a like to a video that will show you how. http://www.youtube.com/watch?v=kBepTImMphM-------------------------------------------------------------------------------------
Car Airbag Reset Tool

Check out your coolant level first, and it may need to be filled. There has been a known promblem of the coolant reservior leaking on the sorento and causing low level of coolant, and causing no heat because coolant wasn't pressurize enought to the termostate until car acutally moving or in high rpm.

http://www.ehow.com/how_6496417_replace-starter-2003-toyota-corolla.html

LOOK IN WATER INLET TO CYLINDER HEAD.

its an easy fix get a new gasket ready and remove old one. before you put in the new one clean both surfaces on cover and head and put a smear of silicone sealer on both sides of gasket and carefully put together and make sure sealent doesnt go into engine tighten all the bolts evenly working in opposites and leave to let sealer set this will cure any leaks

Follow the pipe from the top of the rad. to the engine. the rubber pipe connects to the thermostat housing their is either 2 or three screw's around it remove them lift that off and thats all is to it.

take your old termostate when you bye a new so they can match it up.or call the dealer and tell them your vin and they will be able to tell you what motor you have.

the cost of it i dont know but when you get it your termostate is located inside of your water pump. you have to:

1. take off the belt by looseing the ider pully
2. take off the water pump houseing
3. then unscrew the termostate take it out and the gasket
4. then replace it
5. install in reverse order