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15 Posts
Discussion Starter · #1 ·
Hello guys/gals-

My first post so Ill just jump right in! 馃檪
Here goes:

This generator is showing codes E10, E20 and the red overload light comes on. It fires up for bout 10 seconds then shuts down.

I understand codes mean no communication between inverter and GCU. I tested the harness between them, pin to pin and all was good. I tested generator and seems good (resistance on coils) no shorts.

Im looking for info on how to test the inverter to rule it out as the issue. Also, info on testing GCU. Any info would be great!


Premium Member
1,530 Posts
Hey, I guess everyone has been as busy as I am. You are correct that e10 e20 are inverter gcu communication errors.

The service manual indicates component inspections of the stator, inverter, inverter harness In that order.

I only have info for the Eu7000... but its most likely the same for the EM7000.


5,639 Posts
how old is the gen set and how many hours?
check all of the connectors for green or corrosion..
and pinched harness as well.
you could also have an over crimped connector!!
I found one of those today!! almost pinched in two!!
it showed up with a flir thermal camera..
rare thing but it was a good find.
it was a low current output on L2

yea you might be looking at stator and rotor replacement.
stator could be bad inside..
you need the good test gear like a scope meter and a coil checker for that.
it is best to replace them in pairs if you do them.
big changes in the new replacement units.
better magnets and a bit of a coil tweak as well from the first generation production run.

all of this gear is changing fast by the hour!!
lots of changes for the good on the inverter units!!

I have a parts link for honda parts at
Poust usa bottom of the page for honda parts coupon
use the coupon code at check out.
and they are good prices as well.
order the spare parts too like filters etc.
make the shipping count.

15 Posts
Discussion Starter · #5 ·
so I had to put this gen set on the back burner for a bit. I am now back at it again and have since purchased a service manual for this unit. in following the testing procedure, I tested the stator, book says I should get 40 +5 Vac testing between pins. in doing so im getting upwards of 200+Vac. book goes on to say, call tech line, replace stator if not getting 40 +5 Vac.

you guys/gals are my tech line Im calling on to confirm that the stator is bad and I should replace it with the voltage Im getting? also all testing was done with inverter removed per the books instruction and still get same error codes and red overload led.

any questions or opinions would be great before I purchase any parts.

thanks in advance!

5,639 Posts
make sure to check the connections and crimps on the wires.
yea these gens are a real project to work on.
take your time and photo copy the last page in the manual and write down the numbers you read in the tests.

15 Posts
Discussion Starter · #9 ·
I owe you an apology for not getting back to you when you sent me pm鈥檚, as I said I had to put the gen set on the back burner for a bit.

this gen set was given to me, has 8000+ hours on it, was told it was running fine then shut down and showed error codes, it was used outside to run a 208/240v well pump. not sure how long it was out there.

I will pull out my pin/connector removal tools and check each connector carefully for bad crimp or corrosion since it has lived outside its whole life. I will repost once I do so.

thanks for chiming in as well!

Premium Member
1,530 Posts
That鈥檚 a good meter for troubleshooting. Interestingly the eu7000 manual specifies only using the recoil start for the AC voltage stator test. Maybe do it both ways, and include the readings for each pair of terminals. Same for the resistance test.

Premium Member
1,530 Posts
Hmmm voltages are way out of spec with electric start and only slightly out of spec with pull rope.

The red wire has quite a bit of corrosion, soak in white vinegar and rinse clean the connectors for a quick cleaning. I鈥檇 resnug the crimp as well for good measure.

The resistances look pretty good, I feel like these specs are always slightly off from real world measurements Without issue. Through my research before purchasing an eu7000 ive found that the GCU is one of the more common failures with high hour units. It鈥檚 a $500 plunge though. Does your manual have a GCU test?

15 Posts
Discussion Starter · #18 ·
ok guys-

My bad 馃う鈥嶁檪锔, disregard any of the tests I posted before, I neglected to remove spark plug per the test instructions 鈥渇ollow instructions carefully鈥 (thank you Iowagold). after cleaning terminals on stator to like new condition, continuity test on all pins to and from gcu and inverter (they are all good), I retested stator and inverter. will test governor wires and post, have not done so yet. here is a detailed list of error codes and test procedures I performed:

5,639 Posts
good call on checking connectors, I do see some corrosion on some terminals, is this enough to cause a issue?
View attachment 9634 View attachment 9635 View attachment 9636 View attachment 9637
re do those connections!
inspect the wires for more damage!
and i would solder them!
i see bad crimps and corrosion.
use kester solder and good kester flux.
wipe the copper with flux first crimp the copper to the brass
then solder carefully.
then after it cools crimp the stress relief.
it is a real art to solder a crimp end on...
but it is a better connection for sure.
and dress the connections with dielectric grease after it is ready to plug back in.
pm if you need links on crimpers and connectors...
as well as good solder equipment!
we have a killer butane setup we use here. nice for field service work when you do not have power!
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