Cummins/Onan — Field Coil Short Circuit Test
Testing & diagnosis · field coils
From a Cummins/Onan service manual covering: 10C, 10CW, 10CW-150R, 5CW, 5TW-0R, 6CW-54R, 7.5C, 7.5CW, 8CW. Check it applies to your exact model before use.
Applies to: Cummins/Onan 10CW, Cummins/Onan 10CW-150R
Procedure
- Use a sensitive ohmmeter to test the resistance of each coil winding.
- If one coil reads more than 10% LESS than the average of the other three, it is short circuited.
- On electric cranking models, do not confuse the cranking winding with the shunt winding.
Tools required
- sensitive ohmmeter Amazon
Tool links are Amazon searches (affiliate links); manufacturer special tools may only be available from a dealer.
Specs & values
- Coil reading more than 10% less than the average of the other three coils
Full service-parts list: Cummins/Onan 10CW →, Cummins/Onan 10CW-150R →
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.