Cummins/Onan — Field Coil Open 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
- Tag each lead wire and its connection point when disconnecting.
- Connect one test lamp lead to the F+ coil terminals.
- Connect the other test lamp lead to the F- coil lead.
- If the lamp fails to light, an open circuit in the shunt winding is indicated.
- Repeat the test between the S1 and F+ terminals.
- If the lamp fails to light, an open circuit in the cranking winding is indicated.
Tools required
- continuity type test lamp set Amazon
Tool links are Amazon searches (affiliate links); manufacturer special tools may only be available from a dealer.
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.