Cummins/Onan — Starter Solenoid Test
Testing & diagnosis
From a Cummins/Onan service manual — check it applies to your exact model before use.
Applies to: Cummins/Onan HDKA, Cummins/Onan HDKAH, Cummins/Onan HDKAJ, Cummins/Onan HDKAK
Before you start
- This test involves high electrical currents, strong arcing, and moving parts. Wear safety glass and keep fingers away from the pinion gear.
Procedure
- Secure the starter motor assembly in a vise.
- Connect the motor terminal on the solenoid to the positive (+) terminal of a 12 volt battery using a heavy jumper cable.
- Connect one end of a negative cable to the negative (-) battery terminal.
- Briefly touch the other end of the negative cable to the mounting flange of the motor.
- If the motor does not spin up quickly and smoothly, replace the starter motor.
- If the motor does spin up, replace the solenoid.
Tools required
Tool links are Amazon searches (affiliate links); manufacturer special tools may only be available from a dealer.
Full service-parts list: Cummins/Onan HDKA →, Cummins/Onan HDKAH →, Cummins/Onan HDKAJ →, Cummins/Onan HDKAK →
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.