Cummins/Onan — Relay Check
Testing & diagnosis
From a Cummins/Onan service manual — check it applies to your exact model before use.
Applies to: Cummins/Onan MDKAD, Cummins/Onan MDKAE, Cummins/Onan MDKAF
Procedure
- Connect B+ voltage across relay coil terminals. Relay should activate if coil functional.
- Connect a voltage source to one side of relay contacts.
- Connect voltmeter to other side of relay contact and to other end of voltage source.
- Energize relay; NO contacts good if voltage appears, NC contacts good if voltage reading goes to 0.
Tools required
- Voltmeter Amazon
Tool links are Amazon searches (affiliate links); manufacturer special tools may only be available from a dealer.
Full service-parts list: Cummins/Onan MDKAD →, Cummins/Onan MDKAE →, Cummins/Onan MDKAF →
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.