Onan 5.5 Marquis Gold HGJAB problem

Well, I ran through the oil sensor test and still have the problem. Next up is testing a few other connections, but that will be two weeks out. Life intervenes! LOL

Thx for all the replies. My control board had issues and was not giving any codes. The light just stayed on all the time. The new board from Flight Systems gives fewer codes and seems to be more robust and only shuts down for low oil or no AC output. I emailed them and found that I was testing the single wire oil sensor wrong. The sensor wire has to be grounded to the frame to start and then ungrounded before releasing the start button. I’m busy a few days, but I’ll post back the results. I never saw that grounding process online or on YouTube.

What is the error code when it dies?
(NO AC gives a Not Cranking fast enough/low battery code by the way. A fellow RVer demonstrated that. Thankfully they were parked next to the only LIVE 30 amp outlet in the desert that day..... My Rig

check the brushs on the generator if you take the cover off look where the start switch is look all the way in the back. you will see 2 wires on the brush block make sure they are connected. take the 8mm screw off and pull the brush block off and inspect

check the fuel pump and insure that it does pump enough fuel. just remove hose and pump into a can or bucket.

Incase you do not have a manual . This is just some info I used a long time ago when we had an issue.

Ok - Brief description of the genset functions,
then some troubleshooting info.
When starting the genset, 12v from the control board is
passed to the voltage regulator and then on through the brushes
and slip rings to the rotating field windings. This 'field flash'
produces an initial magnetic field in the rotor - as the rotor
moves past the stationary output windings, this magnetic field
produces approx 45v ac in the output windings while cranking, and
approx 80v once the genset is up to speed. A slightly higher
voltage is produced in the stationary 'quadrature' windings,
which are connected to the voltage regulator. The voltage
regulator uses power from the quadrature windings to increase the
voltage (and thus current) being fed through the brushes to the
rotating field, which increases the output voltage until the
genset output is up to a (nominal) 128v ac. The voltage regulator
then controls the field voltage as needed to hold the output
voltage constant. Once the output voltage has risen above approx
90-95 v, the output from the battery charge winding to the
control board is high enough to energize relay K2, and the
control board switches to 'run' mode (and, in the process,
disconnects the start solenoid, removes field flash from the
voltage regulator, and switches to 'generated' control voltage
rather than 'battery' control voltage).
Troubleshooting:

Disconnect the genset output from the coach and measure the
output voltage. If you see approx 120v, the problem is either the
battery charge winding, the choke heater element shorted, or a
bad control board or the wiring to it. (The choke heater element
is fed unrectified ac from the battery charge winding). Remove
the plastic cover from the choke and measure the ac voltage
between the two terminals - should be approx 20v. If it is, the
problem is the control board or wiring to it - if voltage is low
or nonexistent, problem may be shorted heater element, wiring
from charge winding, or bad charge winding.

If genset output is 45-80v ac, problem may be bad regulator,
bad output or quadrature windings, and/or poor connection to
rotating field due to tarnish buildup on slip rings. Pull air
cleaner and remove cover behind it in genset housing to access
brush block. Measure resistance from one brush lead to the
other - should be approx 25 ohms. If more than approx 35 ohms,
remove brush block, clean slip rings and brush tips, and retest.
If output voltage is still low, check voltage from quadrature
winding to voltage regulator (module mounted in bottom left of
control box) by back-probing pins 11 and 12 of the 12-pin
regulator connector - voltage should be approx the same as
measured at output. If it is, the voltage regulator is bad - if
quadrature winding output is low or nonexistent, check
connections/wiring - winding should measure approx 2 ohms
resistance.

If genset output is (almost) nonexistent ( less than 5v ac),
most probable would be no field flash from control board to
voltage regulator, bad connection from voltage regulator to
brushes, tarnished slip rings, shorted or open rotor windings, or
shorted output windings. Measure brush-brush resistance and
correct if necessary. Set meter to dc volts, hook positive meter
lead to right brush and negative to left brush, and check for
field flash - should be approx 11v dc while cranking. If not
present, hook negative meter lead to ground and back-probe voltge
regulator connector pin 7 while cranking. If you have voltage
here but not at brushes, either voltage regulator or wiring from
regulator to brushes is bad. If you don't have voltage at pin 7,
check for voltage at pin 5 of connector P1 on control board - if
not present here, problem is on control board. I am not sure on the pins since your system is not the same as mine.

Yes. Flipped breakers and checked oil first. That was the first two questions my son asked. Never hurts! LOL.

Did you check the two circuit breakers on the gen it self. Have to ask the oil level.