Skip to content
Open sponsorship. Site bar + newsletter spot, US$50/week.
GENERATORCODES

Home / Briggs & Stratton / 3

15–20 kW standby control board

3

Under voltage

Electrical · Shutdown

Service code 3 on the manual's list is 'Under Voltage / Over Voltage.' The under-voltage chapter says the display scrolls Under Voltage and the remote LED flashes three times. Sensing is at wires 11 (E1) and 12 (E2), between the generator breaker and the control panel. The chapter's causes include loose breaker lugs (it specifies 45 in-lb), overload, restricted fuel, a broken sensing lead, weak engine power, a failed alternator, open wiring, or a failed AVR. Code 9 on the same list is a separate 'Over Voltage' scroll, so this page does not treat code 3 as the over-voltage procedure.

Seen on: Briggs & Stratton 15 kW and 20 kW standby generator systems covered by manual 381268GS Rev. A.

Likely causes

  • Overload or restricted fuel dropping voltage.
  • Loose breaker lugs or an open sensing wire (11/E1 or 12/E2).
  • Alternator or AVR failure.

Checks an owner can do

  1. Remove heavy loads before a restart.
  2. Do not tighten breaker lugs or test sensing wires unless you are qualified. The manual's own tests are done with the breaker open and the set in manual, and they include live voltage checks.

When to call a pro

Under-voltage testing in this manual is a technician sequence, including alternator tests. The no-load window it cites while testing is 240 VAC ±10 percent and 57–62.5 Hz. To reset the service-code system, the manual says to hold OFF until the display stops scrolling the code, hold OFF at least 7 more seconds until the display turns off, leave it off at least 30 seconds, correct the cause, then hold AUTO and reinstall the 15 amp fuse if you removed it.

Source

Briggs & Stratton Service & Troubleshooting Manual, Standby Generator System 15 kW–20 kW, manual 381268GS Rev. A (service code list and the matching code chapters).

Wording follows that document. Firmware can change a threshold. If this page and the manual shipped with your unit disagree, follow the manual.

What fixed mine

No approved reports for this code yet. Send one. It stays in the review queue until it is approved.

Related Briggs & Stratton codes

https://generatorcodes.com/brand/briggs-stratton/3