Cummins/Onan 3100 series — Testing the Float Switch Assembly
Testing & diagnosis · Float switch assembly (day tank)
For the Cummins/Onan 3100 series, from the Cummins/Onan service manual.
Applies to: Cummins/Onan DGBB, Cummins/Onan DGBC, Cummins/Onan DGCA, Cummins/Onan DGCB, Cummins/Onan DGCC, Cummins/Onan DGDA, Cummins/Onan DGDB, Cummins/Onan DGDK, Cummins/Onan DGEA, Cummins/Onan DGFA, Cummins/Onan DGFC
Procedure
- Remove the fuel pump control cover, disconnect the wiring jack and unscrew the assembly from the top of the day tank.
- With an ohmmeter, test for continuity (switch closed) between each pair of colored leads while holding the assembly vertical; replace if any switch is open.
- Lift each float in turn to 1/8 inch (3 mm) below the C-clip stop above it and test for continuity; replace if any switch does not open.
- Use pipe thread sealant when replacing the assembly.
Tools required
Tool links are Amazon searches (affiliate links); manufacturer special tools may only be available from a dealer.
Specs & values
- 1/8 inch (3 mm) below the C-clip stop
Full service-parts list: Cummins/Onan DGBB →, Cummins/Onan DGBC →, Cummins/Onan DGCA →, Cummins/Onan DGCB →, Cummins/Onan DGCC →, Cummins/Onan DGDA →, Cummins/Onan DGDB →, Cummins/Onan DGEA →, Cummins/Onan DGFA →, Cummins/Onan DGFC →
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.