Uu fault code on 20 kW residendial generator

UU is generator under voltage. Check to see if it does it without laod also. if it does you will need a pro to check and ohm the rotor and stator for shorts

If it has a couple hundred hours or more, try cleaning the slips rings on the back of the rotor shaft. They should be very shiny and not black or polished looking.

Check that when you run it, it is not in fact making correct voltage (within about 10% is good), also make sure the engine is coming up to full speed, 3600 or 1800. You could check this with a multimeter that measure hertz. On the main output leads when the genset is running make sure it is getting close to 60 hz. or if you are in an area that uses 50 hz. check for that respectively. There are a couple things that would affect this, one would be your SCR module. There is a test procedure for this which you could find here. http://www.scribd.com/doc/50171916/tp6196-1 . I don't work on marine units, mostly standby so these manuals are for residential. Check your fuses, could even go as far as checking the wiring in the back and wiring and condition of the brushes and sliprings. These actually build field voltage to make 240 or 120 volts whatever your unit is configured to make. The brushes need to sit flat on the slip rings and on a unit with 10 hrs. the sliprings I can't imagine would be very dirty but check that as well. If you have an ADC2100 controller use this manual to go into the controller to verify that it is set for the correct voltage that the machine is built to make. The only other fairly simple thing to check that I've had issues with is if Kohler mounted a fuse block on the side of the cabinet mounted to the genset with no vibration isolation. Check these fuses while attempting to run the unit and make sure you getting steady voltage out of them as sometimes they will vibrate causing pulsed voltage to come out of them and can give you an intermittent UU, UF, or OC fault (undervoltage, underfrequency, overcrank).

The monitoring system of our Kohler propane generator has sent a "UU" message. What does this mean as it causes the generator to shut down 10 seconds after starting? Also how can this be corrected?

Here is the code explained direct from Kohler's manual. I'd disconnect the generator load first.
UU Undervoltage Shutdown occurs if the voltage falls below 80% of the nominal system voltage for more than seconds. Check wiring and connections.
Reduce the load and restart the generator set. —
Check wiring and Check controller configuration, system voltage
and frequency (parameter UU).

Check AC voltage and adjust, if necessary. 5.7
Replace the SCR module and test voltage again. 4.9
Separately excite unit. 5.2
Check stator continuity

See web site for manual :http://www.kohlerpower.com/onlinecatalog/pdf/tp6196.pdf

Means that the engine has turned over for too long without starting. It times out to protect the starter and battery wiring.

U need to make sure that the relay driving ur auto start stay closed all thru the crank cycle.

call koler but ui think is meant high heat as in the thermal circut is shuting you down or low oil
could be a couple of things best bet call kohler

Could be the battery voltage. If your battery is not charging properly, the controller on the unit can do some funky things! Exactly how long does it run for? Is this in auto or manual mode?

Your gas pressure is too low and you may not have a large enough supply pipe. You need at least 10 inches of water column with the engine running to operate an LP vapor fueled engine. Because the engine is starving for fuel, its governor opens the throttle to WOT (so it goes to high revs) but there isn't any fuel to make horsepower with so the output voltage falls and the undervoltage alarm trips.

Carl