Hi,
You may have a catch-22 situation going on.
1. The controller is asserting the Estop as there is no charge pump signal
2. Mach3 is turning off the charge pump as it sees the Estop signal from the controller.
If you go into the Mach3 Config-> General tab, there is a checkbox called "chargepump on in Estop". Make sure that is ticked, as see if that solves your problem.
Cheers,
Peter