Quote:
Originally Posted by customyota
I do a lot of microprocessor stuff as a hobby, so I'm familiar with using pull up resistors on digital circuits, ie. the switch to ground, but I never considered it for analog circuits. I just figured it wouldn't work. Guess I need to do some research. 
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I think its just their to stop it flapping round on say Australian ECU as we have no connection to that evap pressure input. or if the evap pressure sensor sensor goes bad or the sensor/wiring open circuit on vehicles with it fitted the ecu will see 5v on the line and likely trigger a CEL code. conversely if shorted to ground likely triggers cel as well as normal sensor range would be exceeded
They do similar thing on MAP sensor input to they can trigger out of range CEL codes if sensor is out of range
Yes it will effectively limit the voltage range available to something like 0.5 to 4.5 or something like that
more detail here
http://www.ft86club.com/forums/showthread.php?t=94751
specific post here
http://www.ft86club.com/forums/showp...7&postcount=11