Cummins/Onan — Wiring Harness Check
Testing & diagnosis
From a Cummins/Onan service manual covering: MDL3, MDL4, MDL6. Check it applies to your exact model before use.
Applies to: Cummins/Onan MDL3, Cummins/Onan MDL4, Cummins/Onan MDL6
Procedure
- Inspect all wires for breaks, loose connections, and reversed connections; refer to applicable wiring diagram.
- Remove wires from terminals at each end and check each wire end to end for continuity or opens.
- Check each wire against each of the other wires and to ground for possible shorts or insulation breaks.
- Reconnect or replace wires according to applicable wiring diagram.
Tools required
- Ohmmeter Amazon
Tool links are Amazon searches (affiliate links); manufacturer special tools may only be available from a dealer.
Full service-parts list: Cummins/Onan MDL3 →, Cummins/Onan MDL4 →, Cummins/Onan MDL6 →
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.