Cummins/Onan — Testing Commutating Reactors (L21 and L22)
Testing & diagnosis
From a Cummins/Onan service manual covering: DL4, DL6, DL6T. Check it applies to your exact model before use.
Applies to: Cummins/Onan DL4, Cummins/Onan DL6, Cummins/Onan DL6T
Procedure
- Remove reactor leads from terminal board for testing.
- Measure resistance between coils 1-2 and 3-4; should be 0.031-0.37 and 0.037-0.46 ohms at 77 deg F (25 deg C).
- Measure resistance between coils and from any terminal to frame; should be infinity.
Tools required
- ohmmeter Amazon
Tool links are Amazon searches (affiliate links); manufacturer special tools may only be available from a dealer.
Specs & values
- L21 coils 1-2: 0.031-0 FridayParts $227.74.37 ohms
- L21 coils 3-4: 0.037-0.46 ohms
Full service-parts list: Cummins/Onan DL6 →
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.