Good afternoon!

I am working on getting a standby generator working again. I’ve read through the forums and cannot find a similar issue.  Generator was not working when the home was purchased two years ago and has not worked since around 2009 according to the previous owner.  I am just getting around to visiting this and hopefully making it work again.  Home built in 2004, which corresponds to the Generator model number and ATS.  Called Generac and obtained the proper manual. Battery compartment bottom and side panel are corroded pretty bad, and there was no hope of saving the terminals on the old battery.  Rest of the enclosure and motor are in great shape.  I changed the battery terminals and installed a new battery.  Also performed basic maintenance, changed oil, oil filter, air filter, new spark plugs.  Checked all fuses on the Gen, all are good.  Put fuses on generator back in after battery change, made sure the breaker to ATS was off, flipped the switch to ‘Manual’ and it fired right up and ran smooth after about 60 seconds.  It starts right up manually every time I have tried the past 3 weeks and runs smooth, but now the fun part:

-4 flashing red LEDs do flash in manual mode, stating exerciser not set.
-Green LED on ‘system set’ does flash, indicating no utility sense when running in manual/auto mode.
-When panel button moved to Auto with utility power working – it starts right away and runs, will not turn off until switch is moved to off position.  Set Exercise button does not work, it never shuts off after 12 minutes.

With voltmeter:
-Get 122 volts on each of the legs to the dual 50 amp breaker to ground and 244 together.
-N1 to ground gives 120v.
-N2 to ground gives 120v.
-N1+N2 gives 0v.
-I get no DC voltage on wires 23 or 194 when generator is running or off.
-Battery is maintaining 12.1-12.3v each time I check it.

I have not performed a manual flip to generator or done anything in the ATS.  I did measure the wattage out of the house panel to the ATS with all circuits under load.  There’s around 58-5900 watts total on the legs to the ATS.

Generator Model: 04674-2 Natural Gas, 12Kw.
Serial Number: 7668279
100 Amp ATS – Load Center model 4969

Looking for some pointers or next steps.  I would like to do more troubleshooting before calling a dealer and paying tons of $$ on a service call if the unit cannot be fixed or potential repairs would cost more than a replacement unit.

Thank you!


Where are you measuring N1 & N2 voltage at exactly, inside the transfer switch or inside the general control panel?  Measuring N1 to N2 should give you 240 volts at all points along its path to the generator control panel, and if you are getting zero volts then the generator is starting because it thinks Utility power has failed.  Measuring 120v to ground doesn't necessarily tell you anything because one side of the 240v circuit will feed back onto the other side of the circuit through the generator's control panel.

So you need to figure out where one side of the N1/N2 wires is being lost.  It could be a blown 5-amp fuse inside the transfer switch, or it could be that the fuse is good but the fuse holder's clips are loose and not making good contact, or a stake-on has come loose on one of the N1/N2 wires where they land on the fuse block or inside the generator itself.

You may have other problems, but a lack of 240v across N1 & N2 is definitely a point of failure.  You will not get DC voltage on 23 & 194 unless you have let the generator start in Auto mode and the the generator sends the "move to generator" signal to the transfer switch.  If you just have the generator running in Manual you will not get any voltage on 23 & 194.  But if it's running in Auto and you still get nothing across 23 & 194 the you have more problems than just the N1/N2 issue.
In addition to Goofy's post, the battery is slowly discharging due to not having 240vac on N1 and N2, once you have 240vac into the unit the battery charger should pick it up to 13.8 - 14.2vdc, you might just as well disconnect the battery until you fix the 240 volt issue.
Probably one of the 5 amp fuses in the transfer switch is blown hence no 240 volt across N-1 and N-2.  You need to fix this first and should result in the green light being on solid when in automatic and the battery charger should put out about 13.5-14.5 volts.  This will need to be confirmed of course.  It sounds like the generator itself is OK as it is putting out 240 volts L-L.  The 12VDC on the 194 wire should first be checked in the generator with the 23 wire disconnected if there is no 12VDC on 194 to ground with the switch in auto you probably have a bad control board.  You will need to verify 194 back to it connection at the control board but it is likely that is OK.  If you do have 12VDC on 194 then check the disconnected #23 wire to ground you should have 12VDC there also.  If not you need to check the wiring to the transfer switch and the transfer relay for opens or shorts.  If you do these things and report back we will be able to refine our advice as needed. 
Since heavy corrosion in the battery compartment may be an indication of a battery charger issue.  May want to check the condition and output of the charger also.
A warning about the clamp on battery terminals, that clamp on the bare copper with a strap and two 7/16" bolts.

I don't even carry these on my truck.  Always replace the entire battery cable.  

It is a substandard, jackleg repair that a customer should not expect from a factory trained technician.  38" cables cost $9 at O'Reilly, comes with a new bolt and nut.  And are faster to install.  And provide a infinitely better connection.  And do not require destruction or removal of the plastic battery terminal covers.

Most techs lay one cable in the clamp and 6 months later you have a no crank.  The copper is corroded, has that patina, and usually can be pulled out of the terminal by hand.  If I have to make someone else's repair work a little longer, I cut twice as much insulation off and double the wire over before putting it into the clamp.
State your problem, not your diagnosis.

Thank you so much for all the responses.

I turned off power to the ATS, disconnected N1 and N2 signal wires going to the generator in the ATS.  Turned power back on and found the 5amp fuse on N1 was bad inside the ATS.  Replaced the fuse, reconnected signal wires, tested and getting 240V across N1+N2 all the way into the generator.  Moved switch to Manual, generator starts and no more flashing green light!  Battery charger appears to be working, as after 6 hours the battery is reading 13.99VDC, up from 12.1VDC before replacing the fuse.

I disconnect the 23 wire at the Gen.  Moved switch to Auto, generator started immediately and getting 12VDC on 194 to Ground.  Get 12VDC on the #23 wire coming from the ATS.  0 volts on the 23 wire at the Gen while it’s disconnected. 

Turned Gen off, reconnected 23 wire at the Gen, move switch to Auto – nothing happens.  Held down the ‘Set Exercise Timer’ button for about 12 seconds, Gen started and ran for 12 minutes 10 seconds and then turned off.

Dual 50 amp breaker inside generator to ATS is still off.

Anything else to test before proceeding with a manual or automatic transfer?

If I get this all working, I absolutely will change out the battery cables!

Confirm you have 240 L-L at the generator side of the breaker then shut the unit down, close the breaker, set the unit to auto and then kill the feed breaker in the panel.  After 10-20 seconds the generator should crank, start, settle and then transfer the load to the generator.  You should be ready for the next outage.