Cummins/Onan — Electronic governor adjustment/calibration

Adjustments

From a Cummins/Onan service manual covering: 4A2.3, 6A3.4-GS, 6AT3.4-GS, DL4, DL6, QSA3, QSA4, QSA6. Check it applies to your exact model before use.

Applies to: Cummins/Onan DGAB, Cummins/Onan DGAC, Cummins/Onan DGAD, Cummins/Onan DGAE, Cummins/Onan DL4, Cummins/Onan DL6

Procedure

1. Check actuator linkage does not bind through full travel; ensure terminals 7 and 8 are jumpered.
2. Attach tachometer to engine or frequency meter to generator if control panel lacks one.
3. Set Controller GAIN adjustment to second mark from zero.
4. Disconnect governor rod from throttle lever.
5. Place Run/Stop/Remote switch in Run position to start genset.
6. Adjust right stop screw on mechanical governor to obtain 72 Hz (2160 r/min) for 60 Hz gensets or 62 Hz (1860 r/min) for 50 Hz gensets.
7. Adjust left stop screw to just take up slack, then tighten locknut without binding shaft.
8. Stop genset, attach governor rod to throttle lever, start, and adjust Controller SPEED screw for 60 Hz or 50 Hz.
9. Connect full rated load; if genset cannot manage load, shorten governor rod one-half turn and repeat; tighten locknuts.
10. Connect 1/4 rated load; turn GAIN screw clockwise until actuator hunts, then back off until stable.
11. Stop genset, wait 30 seconds for turbo coast down if equipped, restart, and check for speed overshoot.
12. Restart genset and check frequency and stability under various loads.
13. Stop genset and remove tachometer or frequency meter if attached.

Full service-parts list: Cummins/Onan DGAB →, Cummins/Onan DGAC →, Cummins/Onan DGAD →, Cummins/Onan DGAE →, Cummins/Onan DL6 →

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.

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