If you have a 41260 Surge Guard mentioned in the subject? It may have the contacts stuck in the generator position. Here is some suggestions from TRC who made it.
Model 41260, 120/240V, 50
A Transfer Switch, Shore Power checks:
At the pedestal:
A) Left (L1)________Right (L2) ________(Voltages)
Verify that you have approximately 120V between the
center slotted opening (opposite the round opening)
and the two slotted openings on either side. If less than 110V on either side, you may have a pedestal voltage problem.
B) ________(Voltage)
Verify that you have 0 volts between the center slotted opening (neutral) and the round opening (ground).
C) L1 ________ L2 ________(Voltages inside coach)
Verify and record the voltages inside the coach (note location for
future checks). If you have a remote monitor or power
monitoring system, note voltages accordingly.
Additional shore power voltage checks for 41260 Transfer Switch:
At the Transfer Switch shore power input:
D) L1_______ L2 ________(Voltages at shore power)
Verify and record the voltage at the shore power input to the transfer switch: white to black wires (L1), white to red wires(L2).
E) ________(Voltage)
Verify that you have 0 volts between the white wire(neutral) and
the green wire (ground).
F)L1 ________ L2 ________ (Voltages at output)
After the unit powers up, check and record the voltages at the output of the transfer switch: white to black wires (L1) and
white to red wires (L2).
Generator power voltage checks for 41260 Transfer Switch:
At the Transfer Switch generator input:
G) L1 ________ L2 ________(Voltages at input)
Power up the generator, verify and record the voltage at the input to the transfer Switch: white to black wires (L1), white to red wires (L2).
