i was able to get one off of a 2003 suburban. i got the sensor mirror and connectors put it in the car, wiring the grounds powers and ignition wires along with the 2 wires that go to the ambient temp sensor. the temp is alway way above the actual temp. when i put it back on a vehicle that originally had a temp mirror it shows proper temp. i changed out my sensor but still reads pretty high. what could be wrong? is there something in the lan wire that tells it to update the temp display?

 

Unless you mounted the sensor in a really hot place, its probably your wiring. The sensor is going to be a thermistor: http://en.wikipedia.org/wiki/Thermistor

If you have thin, high resistance wire (like LAN cable) it will drive up the resistance of the circuit and indicate an incorrect temperature. Was the original vehicle wired with LAN cable?

 

it had a lan cable but not for the temp display the part of the sensor was just 2 regular wires running to the front of the vehicle i mounted my sensor right next to the hood latch so i could get air coming in through the front of the hood

 

You might try a larger wire equal to or greater than what was in the original vehicle. If you just want to test the theory, I'd think some cheap lamp wire from a hardware store would be good - however you wouldn't want to use that in a permanent installation. For that, you'll need wire with an automotive grade insultation on it. (Regular insulation, or LAN cable for that matter, won't stand up to engine compartment temperatures.)