Can't turn off zmin pull up resister

Here is what I'm using.
Arduino Mega 2560
Ramps 1.4
Marlin firmware

I am attempting to turn off zmin pull up in order to do auto bed leveling. Commented it out both lines. Still have 4.4 vdc on the pin. All other axis go to 0 vdc when commented out. Also, UNcommented disable all min pull ups with the same result.

I thought it was my boards, one or the other. Ordered and received new ones. The new boards were never paired with either old board, but I still have the same result.

Any help here??

Thanks in advance.

Edited 1 time(s). Last edit at 03/06/2015 04:41PM by bobkeyes.

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Not such a NEWBEE anymore
Thanks,

Bob Keyes

Not an expert on that board but pull up resistors are physical and so I would think it needs to be changed on the board.

See my post here:

[forums.reprap.org]

The endstop signal input can float and give unpredictable results if the pullup resistor is not enabled. With the pullup enabled there is 5V on the signal input at all times. In the firmware, set the endstop inverting to true, to insure that the unused endstop never triggers.