Cummins/Onan — Dynamic Rotor/Stator Test
Testing & diagnosis · Rotor/stator and voltage regulator
From a Cummins/Onan service manual — check it applies to your exact model before use.
Applies to: Cummins/Onan HDKA
Before you start
- Electrical shock can cause severe personal injury or death; do not touch electrical wiring during testing.
Procedure
- Stop the generator set.
- Unplug the voltage regulator from the wiring harness.
- Connect a 12-volt battery to the F1/F2 terminals using jumpers.
- Start the generator set.
- Measure outputs at J4-4 - J4-6, L1 - L2, L1 - L0, L2 - L0, Q60 - Q1, S1 - S2.
- Expected: 125 VAC at L1-L2; 62 VAC at other leads; 75 VAC at Q60-Q1.
Tools required
Tool links are Amazon searches (affiliate links); manufacturer special tools may only be available from a dealer.
Specs & values
- L1 - L2: 125 VAC +/- 20 VAC
- Q60 - Q1: 75 VAC +/- 20 VAC
Full service-parts list: Cummins/Onan HDKA →
Source: Cummins/Onan service 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.