Kohler 5ECD EC72 error code -- is there a "most likely" culprit?

[mobocracy]

Last summer my 5ECD would crap out after 5-20 minutes of run time, showing an EC72 error code. Before I could get around to it, I replaced all 4 of my 310DAs batteries -- after 5 years, they were shot (two were actually bulged).

After swapping out with new batteries, the generator decided to run right again and I didn't have any problems with it the rest of the summer. I figured the generator was tied to the worst of the battery banks and whatever it might have for an alternator wasn't able to overcome a pair of worn out Group 31s, and bad 12V supply was causing issues.

Now this summer EC72 is back with a vengeance and the generator won't even crank at all. It shows CC1 on the LED display for a second or two, then EC72.

I have a copy of the service manual and the troubleshooting for this problem runs onto two pages of various voltage, continuity and resistance checks. It feels like this error code is a kind of generic placeholder for a bunch of unrelated issues that are either too uncommon or minor to bother with a specific sensor and unique error code.

Web searches for this problem either have no solution/followup posted or to the extent people have solved it, the solutions are seemingly random. Bad main ground connection (would I even get an error code?), K5 main relay, a resistor failure, bad fuses, and I think a couple of other things, too.

Does anyone with any experience solving this have any tips on what the most likely, do-this-first culprits are? I figure the ground connection and the fuse checks are simple no-brainers, any other obvious starting places?

 

[Korkie]

I wouls start with removing, cleaning and re sucuring all of the electrical connections. Grounds, positive cables, sensors, anything that has a wire going to it. You would be surprised at what a seemingly "looks good visually" connection can cause. I had a problem with mine just not wanting to start at all. After cleaning connections up and trying to start after every few, it turned out to be the fuel pump connection. I don't have any way to read codes on mine.

 

[mobocracy]

I wouls start with removing, cleaning and re sucuring all of the electrical connections. Grounds, positive cables, sensors, anything that has a wire going to it. You would be surprised at what a seemingly "looks good visually" connection can cause. I had a problem with mine just not wanting to start at all. After cleaning connections up and trying to start after every few, it turned out to be the fuel pump connection. I don't have any way to read codes on mine.

My philosophy isn’t to always blame the yard, but I noticed an amount of spilled oil in the bottom pan near the ground terminal. I cleaned that up and cleaned and re-torqued the ground connection and it started right up!

…and then died after 20 minutes with EC72 again.

Pulled and cleaned all the outside connectors and fuses, too.

What I’m finding is that it won’t restart immediately, but if left to sit for 5 minutes it will start and run normally for about 5-10 minutes before dying with an EC72 code.

One thing I’m suspicious of is the F5 fuse holder. When I checked fuses it didn’t look secure and it was hard to get seated securely. This is the ECU supply voltage fuse and it would make sense that a poor connection here could throw EC72 codes (it’s even a service manual voltage test). I managed to extend the flanges that hold it in and have it mounted securely now. Running another test to see what kind of runtime I get now. If I get more than 10 minutes I’m going to call it good, since no run time past the first one was more than 10 minutes.

Followup: After better seating/securing the F5 fuse, it ran without incident for about 12 minutes, where I then switched it off and then back to auto. I'm sort of convinced I fixed the issue. I'm going to run it when I'm out today and see how well it works, but it will sure be great if that was all it was.

 

[mobocracy]

The final(?) follow-up on this is that it seems all my EC72 issues were probably caused by the fuse holder.

Once I fixed the retention tabs (the little bent out bits on the removable cap end of the fuse holder) and got that fuse seated well, no more EC72 errors and the generator stopped quitting. That, and cleaning up the oil the marina spilled that ended up on the ground stud (though I think that was more of an issue for cranking).

The fuse holder system is kind of crappy. I was surprised they're all friction fit, no threads of bayonet style locking lugs on the cap. I had a brief moment where I wondered how hard it would be to retrofit a blade-style fuse holder, but then I made a big margarita and stopped thinking about that.

 

[Tacoma290]

Glad you found it and thanks for follow-up to close the thread for someone to learn from.
An entire generator does not work based on one of the least costly items...

 

[mobocracy]

Glad you found it and thanks for follow-up to close the thread for someone to learn from.
An entire generator does not work based on one of the least costly items...

It's crazy, isn't it? I had a kind of mild panic attack when I first couldn't get the F5 fuse cap back on. It took a fair amount of looking/thinking about why it wouldn't stay on to realize that the only thing holding it on are the little tabs making friction with the insert. I wonder how many of these damn things have found there way into the way back of the bilge when they fell back out!

I still keep thinking about how much effort is involved in retrofitting a blade style fuse block. Went so far as to look up the options on BlueSeaSystems.Com.