JD 4720 err81 on dash - died - spin no start HELP

[Brown Dog]

I was mowing grass with finishing mower at 2000 rpm.

No sticks. I only use this tractor for mowing.

I mowing crossways on a slight Incline with my right side higher.

This happened 3 separate times.

 

[arlen4720]

In that case, I would unplug and reseat the computer connections, check grounds/power wiring, and CAN bus wiring.

 

[jenkinsph]

I do need a svc manual.

I read wher ground wires could be loose on the frame.

Could that throw these codes ?

My tractor had a loose ground to the computer when new and it caused it to loose programming twice before the dealer found the problem. Mine would start but not move when this happened. Had to have a flat bed wrecker take it to the dealer.

 

[Bartron]

Brown Dog, did you ever get this problem sorted? I have the exact same issue (spin no start and same error codes) on my 4520 and am hoping to gain some insight.

 

[Brown Dog]

I had to unhook battery to get mine to restart, every time this happened.

Mine was overheating & shutting off from max temp reached.

My air filter was restricted & grass clippings on grille.

This 4720 has always ran right at the edge of red on gauge.

I removed the Tstat against everyone's advise & it now runs around 3/4 of the green.

It hadnt missed a beat since.

 

[Bartron]

I had to unhook battery to get mine to restart, every time this happened.

Mine was overheating & shutting off from max temp reached.

My air filter was restricted & grass clippings on grille.

This 4720 has always ran right at the edge of red on gauge.

I removed the Tstat against everyone's advise & it now runs around 3/4 of the green.

It hadnt missed a beat since.

Thanks Brown Dog, with your suggestion I was able to get my beast going. I tried to unhook the battery but the leads were stuck pretty good so I opted to pull the 'Display' fuse which seems to also supply the CPU. Put the fuse back and she started with no issue or warnings. Ran her for 3 hours with no issues. I noticed the temp seemed a tad closer to the red than normal. I had blown the radiators out and will likely change the coolant. Thanks again!

 

[Brown Dog]

YW. Glad you got it going.
Keep that air filter clean & it'll run cooler too.

 

[Wirednut40oz]

290 hour 4720 hydro.
I was mowing today & it died.
Temp hand was a lil hi but rad is clean & AF level full

I pressed dash buttons & seen
err 04 79 81 82 & 86 but 81 was showing when eng died.

Any ideas ? As manual is useless.

Hi Brown Dog,
I’m having this same issue, I’m just wondering if you remember the salutation to this problem?

 

[Brown Dog]

You’ll get scolded by ppl on here for reviving an old thread LOL
I’m just kidding & don’t care : I do it too

I’m old school & not too InnerWeb savvy.

Welcome aboard.

I had to remove & discard the thermostat & it fixed my problem & kept the engine temp in the normal range mowing at 1700+ rpm for hours while I mowed my farm.

I sold the 4720. I miss it but now using two Kubota ZD1511 4cyl turbo diesel 72 inch zero mowers.

 

[Brown Dog]

Hi Brown Dog,
I’m having this same issue, I’m just wondering if you remember the salutation to this problem?

Keep us posted on your outcome