Cummins/Onan — Flashing the Field
Operation · Exciter field
From a Cummins/Onan service manual — check it applies to your exact model before use.
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Before you start
- Do not maintain field flash connection to exciter circuit longer than 5 seconds.
- Incorrect field flashing procedures can damage regulator.
Procedure
- With GenSet in operation: Start GenSet and operate at normal r/min.
- Touch positive battery lead to TB1-9 of VRAS-2 and negative lead to TB1-10. Hold just long enough for voltage to build to normal operating level, then remove.
- Check generator voltage and shut down GenSet. Restart and run at no load. Unit must build up voltage without field flashing. If not, shut down and check wiring continuity.
- With GenSet shut down: Touch positive battery lead to TB1-9 and negative lead to TB1-10 of VRAS-2.
- Hold leads in place for no longer than 5 seconds.
- Start GenSet and run at no load. Unit must build up voltage without field flashing. If not, shut down and check wiring continuity.
Tools required
- 6-volt dry cell battery Amazon
- 12-amp 300-volt diode Amazon
- 2-watt 20- or 40-ohm resistor for 12V or 24V source Amazon
- Jumper leads Amazon
Tool links are Amazon searches (affiliate links); manufacturer special tools may only be available from a dealer.
Specs & values
- Hold no longer than 5 seconds
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.