Generac — Testing Generator Under Load
Testing & diagnosis · Generator set / transfer switch
From a Generac owner's manual — check it applies to your exact model before use.
Applies to: John Deere 4.5 L engine, Generac 4.5L engine, Iveco/FPT 4.5L engine
Before you start
- High voltage present at transfer switch and terminals
Procedure
- Verify generator OFF and all loads off
- Turn off utility power supply to transfer switch
- Manually set transfer switch to STANDBY
- Press MANUAL to crank/start engine and allow warm-up
- Set generator MLCB to ON (CLOSED)
- Turn on circuit breakers/loads supplied by generator
- Connect AC voltmeter/frequency meter across E1,E2,E3 and verify voltage near rated value; verify not overloaded with clamp amp meter
- Run at full rated load 20-30 minutes, listening/inspecting for abnormal operation
- Turn off loads, set MLCB OFF, run at no-load 2-5 minutes, then press OFF
Tools required
Tool links are Amazon searches (affiliate links); manufacturer special tools may only be available from a dealer.
Source: Generac owner's manual. Steps and values are as documented; always cross-check against the official manual and any later revisions for your exact serial number before servicing.