Cummins/Onan — Adjusting Voltage (PMG Excited Alternators)
Adjustments · Voltage regulator
From a Cummins/Onan service manual — check it applies to your exact model before use.
Applies to: Cummins/Onan MDDC
Before you start
- Hazardous voltage - touching uninsulated live parts can cause severe personal injury or death
Procedure
- If fitted with a sound shield enclosure, remove the front access panel below the control box.
- Remove the voltage regulator access cover.
- Push the Single/Parallel Operation Switch up to SINGLE.
- Start the genset, let voltage and frequency stabilize and disconnect all loads.
- Turn the Voltage Trimmer clockwise to increase or counterclockwise to decrease voltage.
Tools required
- Small flat-bladed screwdriver Amazon
Tool links are Amazon searches (affiliate links); manufacturer special tools may only be available from a dealer.
Full service-parts list: Cummins/Onan MDDC →
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.