PIC Input question

[thekyguy11]

As part of my project, I want to monitor the engine coolant temp in a vehicle. The coolant sensor uses a 5v input, and the output (varied based on temperature) goes back to the ecu. If I connect a wire to the sensor return, say near the ecu, and have it as an analog input into a pic, is it going to alter the temp reading going to the ecu?

Sorry for the newb question, and thanks for any answers.

 

[Nigel Goodwin]

It depends on the output impedance of the sensor.

 

[thekyguy11]

How could I determine what the output impedance of the sensor is?

 

[Nigel Goodwin]

Probably not very easily?, perhaps the best solution is to use a high input impedance buffer from the sensor to the PIC.

 

[thekyguy11]

I have no idea what that means...I've got a lot to learn.