Z Axis wont go down in ponterface!!!

So ive decided to build a prusa i2 and everything was going fine until i tried turning it on and calibrating the x,y,z axis'....x and y are fine but for some reason z wont go down when i try to make it in ponterface... im using RAMPS 1.4 and ive been thru the wiring a couple times to see if everything is hooked up well...it does go down about ten steps when i push Z HOME but it wont go down otherwise..if someone can maybe shine some light on what i might be doing wrong that would be awesome..whatever info you need let me know and i will provide it asap...Ponterface and sprinter are the programs im using..

Edited 1 time(s). Last edit at 12/03/2013 04:43PM by Versone.

First guess would be something wrong with the z end stop. If it thinks it's at limit, it will not go towards the end stop.

This is a common problem. I think you'll find the answer somewhere if you search the forum for limit switch

As far as I can remember the command to display the limit switch values is M119

Move X Y and Z in their positive directions by 10mm, and then try M119 all three limits should not be activated

If they are activated, try holding the switches as if the carriage was pressing onto them, and issue M119 again.
If the state changes, for the switch you are holding, you may have wired the switch the wrong way around (I think this may also be configuratble in Marlin), but it may be easier to re-solder etc

If the value doesnt change, I suspect you've got a bad contact or its not plugged into the correct socket.

All of the end stop switches can be configured for location and sense (open or closed) in the firmware.