Cummins Onan · HGLAA PMA-equipped generator sets

Code 26Alternator under voltage

Permanent-magnet alternator output voltage was below its permitted range.

Published by RV Fault Finder · Independent referencePrimary source checked August 2026How this guide is researched →

What it means

Plain-English answer

The controller saw low PMA output. Cummins lists fuel level, extreme operating conditions, excessive load, service needs, and blocked cooling airflow among the initial considerations.

Owner-safe checks

What to check first

01
Confirm the vehicle fuel level is above the generator pickup threshold.
02
Disconnect loads and check exterior intake and exhaust ventilation for blockage.
03
Let an overheated set cool and confirm scheduled maintenance is current.

Safety boundary

Stop and call a technician when

The code returns with no connected load.
Internal PMA testing or wiring inspection is required.

Primary reference

Check the exact manual

Applicability: HGLAA PMA-equipped generator sets. The data plate and specification letter determine which procedure is correct.

Open Cummins Onan operator manual ↗Source reviewed August 2026