The pump relay (if you have one) will be located on the ground side of the water pump. Follow the 12v negative (ground) wire from the pump to the controller relay.
For a quick test, check the voltage in the 12v+ feed to the pump - it should be available at all times. If you have +12v to the pump but it doesn't run, try making a temporary ground connection for the pump (a jumper to the nearest chassis ground point). If the pump runs, the problem is the ground, probably the controller. If it doesn't run, it's more likely the pump itself. The test should be done when there is little or no pressure in the water lines so that the pump pressure switch sees low pressure and switches on.
Former owner of 2004 American Tradition and several other RVs
Home is in the Ocala Nat'l Forest near Ocala, FL
Summers in Black Mountain, NC