Generator will not transfer load, controller shows E-12

Safety: High voltage is present inside the generator and transfer switch. Isolate the generator and lock out all power sources before opening any covers.

• Check controller readings: Verify the phase-to-phase voltage displayed on the CAT controller. If significantly below nominal (e.g., 208/240/480 V), proceed with caution.
• Inspect main output connections: With power isolated, open the generator terminal box and check that all stator and output lugs are tight and free of discoloration or burning.
• Voltage regulator connections: Locate the AVR module. Inspect its connectors for looseness or corrosion. Reseat plugs firmly.
• Check sensing leads: Ensure the voltage sensing wires from the generator output to the AVR/controller are intact and correctly landed per the wiring diagram.
• Test with no load: After reassembly, run the generator with no load and monitor voltage. Do not adjust AVR settings unless you have the CAT procedure and tools.

If voltage remains low, the AVR or generator windings may be faulty. Replacement and further testing should be done by a qualified CAT technician.