L4701 P0605 code after battery cable failure

[North Idaho Wolfman]

The TSB is listed in post #3.

Yep missed that!

 

[whitetiger]

The mechanic mentioned they put out a new service bulletin last week as well-not sure if he was referring to the old one or if there is a newer one out now

The TSB was last updated on Nov 13 2023 so the tech is a little bit behind.

 

[lugbolt]

this subject highlights MAINTENANCE. Battery cables don't usually break suddenly unless struck by something causing it to, normally they get corroded and fail that way. That usually takes a while. Gotta keep an eye on stuff, especially the newer stuff because they are MUCH more sensitive to voltage spikes among many other things. Glad Kubota issued a bulletin for it, but there are a few of these tractors out there that may not be covered by the bulletin. For everyone, you gotta keep an eye on things. These are not the old tractors that you could fix with a piece of bailing wire and a hose clamp and last you another 40 years.

 

[NCL4701]

Question remains unanswered: How do you disconnect/reconnect the battery without toasting the ECU?

My non-Kubota tech interpolation is the root of the problem is whatever regulates the voltage (maybe a voltage regulator?) spikes the voltage coming out of the alternator when there’s a battery connection failure. ECU is not protected from voltage spikes so it gets toasted. If the engine isn’t running, there is nothing coming out of the alternator. (I’m not an electrical genius but I’m reasonably sure an alternator that isn’t spinning won’t produce anything.)

So that would mean there are two conditions precedent to toasting the ECU: 1) The engine must be running. 2) There must be a failure of at least one battery connection.

If that’s true, and there’s a failure of a battery connection on a non-running engine, the result is it won’t start. The ECU will NOT be toasted.

If I change the battery, all I have to do to protect the ECU is make sure the engine isn’t running and don’t hook it up backward.

If, for some unknown reason I wanted to kill the ECU on my L, all I have to do is disconnect one or both battery connections while it’s running.

Since there are three, and probably more than three, people on this thread that know WAY more than I do on this subject, confirmation or correction of the above would be appreciated.

 

[abingram]

I called the dealership where I bought it. Honestly was not looking for much help because when I bought it, they were not much help. They have changed owners and so far are amazing. Identified my L3901 as one within the campaign to correct. It all on them. They picked it up today and said they would bring it back when fixed.
I am wanting expectantly now. But got a lot of honest, real help. It the repair cost me nothing, I’ll be surprised but even a little is better than $2,400 for the ECU.
I’ll let you know.

 

[abingram]

Question remains unanswered: How do you disconnect/reconnect the battery without toasting the ECU?

My non-Kubota tech interpolation is the root of the problem is whatever regulates the voltage (maybe a voltage regulator?) spikes the voltage coming out of the alternator when there’s a battery connection failure. ECU is not protected from voltage spikes so it gets toasted. If the engine isn’t running, there is nothing coming out of the alternator. (I’m not an electrical genius but I’m reasonably sure an alternator that isn’t spinning won’t produce anything.)

So that would mean there are two conditions precedent to toasting the ECU: 1) The engine must be running. 2) There must be a failure of at least one battery connection.

If that’s true, and there’s a failure of a battery connection on a non-running engine, the result is it won’t start. The ECU will NOT be toasted.

If I change the battery, all I have to do to protect the ECU is make sure the engine isn’t running and don’t hook it up backward.

If, for some unknown reason I wanted to kill the ECU on my L, all I have to do is disconnect one or both battery connections while it’s running.

Since there are three, and probably more than three, people on this thread that know WAY more than I do on this subject, confirmation or correction of the above would be appreciated.

that is what I understood as the problem. Disconnecting the battery and then connecting it will fry the ECU. How to do correctly? I do t know. Hook positive. Then negative. Then hit your knees and pray before turning the switch.

 

[MapleLeafFarmer]

Question remains unanswered: How do you disconnect/reconnect the battery without toasting the ECU?

ici the WSM