Cummins/Onan LS-15M — Testing the Float Switch Assembly
Testing & diagnosis · Day tank float switch assembly
For the Cummins/Onan LS-15M, from the Cummins/Onan service manual.
Applies to: Cummins/Onan DFAA, Cummins/Onan DFAB, Cummins/Onan DFAC, Cummins/Onan DFBF, Cummins/Onan DFCB, Cummins/Onan DFCC, Cummins/Onan DFCE, Cummins/Onan DFE
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 electrical continuity (switch closed) between each pair of colored leads while holding the assembly vertical.
- Lift each float, in turn, to 1/8 inch (3 mm) below the C-clip stop above it (use a feeler gauge) and test for electrical continuity.
- 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
- Switch 1 - Shutdown, Switch 2 - Low Fuel, Switch 3 - Pump On, Switch 4 - Pump Off, Switch 5 - Hi Fuel
- Lift each float to 1/8 inch (3 mm) below the C-clip stop
- Replace assembly if any switch is open when vertical or does not open when lifted
Full service-parts list: Cummins/Onan DFBF →, Cummins/Onan DFCC →, Cummins/Onan DFCE →, Cummins/Onan DFE →
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.