Cummins/Onan — Voltage Adjustment (HGJAD, HGJAE, HGJAF)
Adjustments · Controller A1
From a Cummins/Onan service manual covering: 5.5 HGJAA, 5.5 HGJAB, 5.5 HGJAC, 5.5 HGJAD, 5.5 HGJAE, 5.5 HGJAF, 7.0 HGJAA, 7.0 HGJAB, 7.0 HGJAC, 7.0 HGJAD, 7.0 HGJAE, 7.0 HGJAF. Check it applies to your exact model before use.
Applies to: Cummins/Onan 5.5 HGJAD, Cummins/Onan 5.5 HGJAE, Cummins/Onan 7.0 HGJAD, Cummins/Onan 7.0 HGJAE
Before you start
- Hazardous voltage: touching uninsulated live parts can cause severe injury or death
Procedure
- Disconnect all generator loads and connect accurate AC volt and frequency meters.
- Start genset; let voltage and frequency stabilize 5 to 10 seconds.
- Rapidly press control switch to START 6 times within 1 minute of start.
- Adjust up: press START and release quickly (voltage rises about 0.6 volt).
- Adjust down: press START and release after about 2 seconds (voltage drops about 0.6 volt).
Tools required
Tool links are Amazon searches (affiliate links); manufacturer special tools may only be available from a dealer.
Specs & values
- Each adjustment changes voltage approximately 0.6 volt
- Normal operation resumes 20 seconds after last adjustment
Full service-parts list: Cummins/Onan 5.5 HGJAD →, Cummins/Onan 5.5 HGJAE →, Cummins/Onan 7.0 HGJAD →, Cummins/Onan 7.0 HGJAE →
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.