# 9986 cotton picker electrical problem



## Loganfarms (Aug 25, 2016)

I've got a cotton picker that has an electrical issue that no one can figure out including several well respected John Deere techs. When the picker starts all the picking unit warning lights on the overhead panel blink and sound an alarm. The problem is erratic although as of now it has been happening for several days and will not quit. When you start the picker the picking unit warning lights blink on the overhead and sound an alarm. When this occurs nothing will work on the operators console. No hydraulic functions or electric functions on the handle or console to the right of the seat. The picker will move but the fan will not engage, units will not engage and no basket functions. Nothing we do will make it return to normal except continuing to kill the machine and restart it. This may last minutes or days. Please help with suggestions!


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## BigT (Sep 15, 2014)

Hello Loganfarms,

John Deere techs should be a way better source than me, but when you have a massive alarm light attack, I would look for a circuit common to all. Like a defective/intermittent ground to the picking unit warning lights on the overhead. Or maybe a defective computer? Maybe the keyswitch?


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## Loganfarms (Aug 25, 2016)

We have swapped computers out with other pickers and it does not go away. We have disconnected all row unit alarms and that doesn't help. It could be a ground somewhere but we have been unable to locate it. Tell me more how the key switch could affect it? Seems to work fine. We did have a fire several years ago and we replaced all major wiring harnesses.


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## BigT (Sep 15, 2014)

Can you run a separate ground wire to your picking unit warning lights on the overhead? Check with your JD techs first, to be sure this is not an isolated ground system. The keyswitch provides power to the overhead warning light system, possibly a poor connection??


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## Loganfarms (Aug 25, 2016)

I went out this afternoon to try some more troubleshoot and everything is working perfect and did all afternoon. This makes it very difficult to figure out. I will continue to try it daily until it messes up,again. Anyone with any more ideas?


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## Deereman252 (Oct 2, 2016)

*Doing the same thing.*

Did you find the problem on your machine? My picker is doing the exact thing!!


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## Loganfarms (Aug 25, 2016)

I have never figured it out. We keep cranking it and killing it until it stops doing it. Sometimes it takes 25 or 30 times and then it may not do it for a week. I have no idea what to do next. Sometimes it seems to help if we turn the key on and wait awhile before we crank it. Very frustrating when you have cotton to pick. How long has yours been doing this?


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## Deereman252 (Oct 2, 2016)

Started last week. Don't know if it's a ground problem or not.


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## Loganfarms (Aug 25, 2016)

Have you had any luck fixing the electrical issue with your picker?


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## Loganfarms (Aug 25, 2016)

I hope everyone is finishing up picking but I never did figure out my electrical issue. If anyone has any more ideas please pass them along.


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## SoCoPnut91 (Aug 4, 2017)

My picker is doing the exact same thing.... did y'all find out how to fix it?! Please reply asap. Thanks


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## Len Givens (Nov 24, 2017)

SoCoPnut91 said:


> My picker is doing the exact same thing.... did y'all find out how to fix it?! Please reply asap. Thanks


Did you get your picker straighten out? I have a 9986 doing the same thing too.


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## Lazy W (Nov 10, 2018)

Len Givens said:


> Did you get your picker straighten out? I have a 9986 doing the same thing too.


did u fix


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## Lazy W (Nov 10, 2018)

Len Givens said:


> Did you get your picker straighten out? I have a 9986 doing the same thing too.


did u figure it out


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## Lazy W (Nov 10, 2018)

SoCoPnut91 said:


> My picker is doing the exact same thing.... did y'all find out how to fix it?! Please reply asap. Thanks


did yall fix it


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## RC Wells (Dec 26, 2008)

Not sure if this any help, but I spent a week visiting a friend in Mississippi, and p#ssed three days chasing the same sort of problem on his 9986. Other than my opinion of the machine is best fixed with "buy something else," after chasing ghosts I found that JD sells an electrical connector service kit for the various production serial number runs, and replacing all the modular connectors provided in that kit solved the problem.

JD techs ran diagnostics and found nothing.

Replaced the old connectors, and packed all the new plugs with water displacing dielectric filler and grease from Ham Radio Outlet, and the problem has appeared to go away.

Seems he routinely power washed his unit and the moisture ate the connectors. They were not adequately sealed against moisture in the first place. He uses air and just blows it out now.


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## Lazy W (Nov 10, 2018)

RC Wells said:


> Not sure if this any help, but I spent a week visiting a friend in Mississippi, and p#ssed three days chasing the same sort of problem on his 9986. Other than my opinion of the machine is best fixed with "buy something else," after chasing ghosts I found that JD sells an electrical connector service kit for the various production serial number runs, and replacing all the modular connectors provided in that kit solved the problem.
> 
> JD techs ran diagnostics and found nothing.
> 
> ...


thank you i ordered monitor/computer we will see


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## Lazy W (Nov 10, 2018)

Lazy W said:


> thank you i ordered monitor/computer we will see


not sure if problem my heads wont go up or down


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## bbirder (Feb 26, 2006)

I have no experience with cotton pickers but I was thinking moisture. I think RC found the problem.


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## Jay Paul (Oct 28, 2019)

I have a 9986 and my heads won’t go up or down and we haven’t figured out anything


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## lexc269_6243 (Oct 28, 2021)

Lazy W said:


> not sure if problem my heads wont go up or down


 check fuses and relays under back rest of seat beside you anything to do with picker heads are suspect. Alsobehind the cab on basket bulk head there is a cover to valve bodies there will be magnetic operated spool valve for header up and one for down switch magnets see if header now goes up and will not go down. Also weather pak plug unplug and check for power when pressing up button and power when pressing down button also check the switch on hydro handle they need replacing a lot.. it's been to long ago to remember exact valve spool location but the issue is between handle and valve body every time I've seen a issue


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## lexc269_6243 (Oct 28, 2021)

BigT said:


> Hello Loganfarms,
> 
> John Deere techs should be a way better source than me, but when you have a massive alarm light attack, I would look for a circuit common to all. Like a defective/intermittent ground to the picking unit warning lights on the overhead. Or maybe a defective computer?





Loganfarms said:


> I've got a cotton picker that has an electrical issue that no one can figure out including several well respected John Deere techs. When the picker starts all the picking unit warning lights on the overhead panel blink and sound an alarm. The problem is erratic although as of now it has been happening for several days and will not quit. When you start the picker the picking unit warning lights blink on the overhead and sound an alarm. When this occurs nothing will work on the operators console. No hydraulic functions or electric functions on the handle or console to the right of the seat. The picker will move but the fan will not engage, units will not engage and no basket functions. Nothing we do will make it return to normal except continuing to kill the machine and restart it. This may last minutes or days. Please help with suggestions!





BigT said:


> Hello Loganfarms,
> 
> John Deere techs should be a way better source than me, but when you have a massive alarm light attack, I would look for a circuit common to all. Like a defective/intermittent ground to the picking unit warning lights on the overhead. Or maybe a defective computer? Maybe the keyswitch?


It also could be a common ground circuit #99 it is used daisy chained from one relay to next to next for 12v activated relays


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