# JD 6420 help PLEASE!



## eberlej (Oct 20, 2009)

I have unlimited access to my neighbors JD 6420 and have wired it for GPS and a remote controlled linear actuator to engage a fertilizer spreader from the cab. I was cycling the actuator and noticed a a breaker tripping (one I installed for the actuator) and quickly disconnected everything. I think I exceeded the duty cycle of the actuator.

THE PROBLEM: No tach display, left hand reverser no longer responds, throttle will not respond. I'm too freaked out to see what else is not working. Tractor starts and idles and the a/c still works. Someone please tell me it's just a fuse! It got too dark on me to go through all the fuses and the fuse panel isn't much help.

Thoughts please.


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## Bonfire (Oct 21, 2012)

I would get a flashlight and start checking fuses. Should be map of the fuses on the inside of the back panel behind the seat.


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## JMT (Aug 10, 2013)

Not sure if this holds true for a 6420 but it might. I had a short and a handful of things quit working on my Kubota m120. Fuses were good but a fusible link had blown that fed the fuses. So make sure that you have power to the fuses when you are checking them.

Since you have several things out at once it might be a fusible link or a circuit breaker, but someone else will have to be more specific for the 6420.


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## eberlej (Oct 20, 2009)

The map is difficult to decipher and the fuses don't have the exposed contacts that you can check with a probe. I guess I will start pulling the fuses one at a time excluding the one that obviously are a non-factor i.e., lights, a/c, etc.


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## somedevildawg (Jun 20, 2011)

eberlej said:


> I have unlimited access to my neighbors JD 6420 and have wired it for GPS and a remote controlled linear actuator to engage a fertilizer spreader from the cab. I was cycling the actuator and noticed a a breaker tripping (one I installed for the actuator) and quickly disconnected everything. I think I exceeded the duty cycle of the actuator.
> 
> THE PROBLEM: No tach display, left hand reverser no longer responds, throttle will not respond. I'm too freaked out to see what else is not working. Tractor starts and idles and the a/c still works. Someone please tell me it's just a fuse! It got too dark on me to go through all the fuses and the fuse panel isn't much help.
> 
> Thoughts please.


Did you find the fuse diagram behind the seat? It's on the panel that comes off by pushing down on tHe two black tabs and pulling. It may even have a circuit tester in the panel, but i Would use a test light....
Start by checking the fuses, I would thnk you do have either a fuse or fusable link problem like JMT referred to. 
Where was the unit hooked up to for power? I assume you run a power wire to 12v on the tractor? The actuator is remotely controlled, ie. rf remote like a vehicle?


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## somedevildawg (Jun 20, 2011)

Didn't see your post, so you did find it.....just turn it like the fuses are and hold it right above the holder, there's like 5 rows of relays/fuses. Mine are mostly symbols but fairly easy to figure out.....I hate those damned fuses......


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## Braford (Jul 25, 2014)

Does the display not give you a code? My engine speed sensor went out on mine but it did give a code on the display. Did the same as you are describing. Mine is a powerquad 6420 2wd. It would run but not go forward or revers. Basically a $240 repair at the dealer to replace the sensor.


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## Bonfire (Oct 21, 2012)

I just look at mine. Have you checked everything in the F03 column of fuses? The BCU ones.


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## eberlej (Oct 20, 2009)

Bonfire said:


> I just look at mine. Have you checked everything in the F03 column of fuses? The BCU ones.


I looked at the fuses and they all appear to be okay. It was in the F03 column that I plugged the actuator into a blank.



Braford said:


> Does the display not give you a code? My engine speed sensor went out on mine but it did give a code on the display. Did the same as you are describing. Mine is a powerquad 6420 2wd. It would run but not go forward or revers. Basically a $240 repair at the dealer to replace the sensor.


The display doesn't show anything, nor do any of the indicator lights light up as they do when you start it.

I broke the news to the owner and told him I didn't sleep well last night. He's off to Louisiana with his wife at a Casino. He told me not to lose any sleep over it and that it probably isn't that big of a deal. I can't say enough about having a neighbor and friend like him.

Tomorrow I will be going in to the dealership to get some other parts and will talk to the service manager who's a good friend of the owner. I'll post the result once it's repaired.


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## Bonfire (Oct 21, 2012)

eberlej said:


> I looked at the fuses and they all appear to be okay. It was in the F03 column that I plugged the actuator into a blank.
> 
> The display doesn't show anything, nor do any of the indicator lights light up as they do when you start it.
> 
> ...


You might want to take the outside cover below the glass off and see if you see anything amiss there.

You checked the continuity of the fuses with a meter?


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## jr in va (Apr 15, 2015)

Check the alternator output,ton my 6640 Ford,if voltage drops below a certain point,the tach and PTO will not work.


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## somedevildawg (Jun 20, 2011)

jr in va said:


> Check the alternator output,ton my 6640 Ford,if voltage drops below a certain point,the tach and PTO will not work.


On the 6420 it will display "alternator malfunction" if no voltage is present from the alt. 
I'm bettin there is a fusable link or fuse for the FO 3 bank that's blown. I would only tie in the actuator to the aux circuit that Deere provides behind the seat in the future.....or better yet, run to the battery. What's the current draw in amps of the actuator? Check that access cover that Bonfire mentioned, a fusable link would be my guess.....


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## eberlej (Oct 20, 2009)

Problem solved! In short, it was a fuse. What made it difficult to find is that the German fuses have to be pulled and each one needs the continuity checked as a couple of you suggested. I started pulling them and checking with an ohm meter but found that process to be slow and cumbersome and thought I could tell by looking at the fusible strip visible on the top edge of the fuse. The JD service manager also advised to check each fuse but to use the built in continuity checker provided in the fuse panel. The 6420 has a fuse blank that when you touch the contacts with the key on, a horn will sound if the fuse is good. I used my leatherman to pulled them one at a time and in quick order went down the line. It turns out that the 30 amp mark "ELX" is important. That was the sweetest sound of silence I've heard in a while.

Now all is well and thanks for the help.


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## somedevildawg (Jun 20, 2011)

Glad u got it going, good for you......careful with add ons in the future, lots of sensitive electronic components on the 6420. Sweet deal ya have there and I would do anything I would have to do to keep that relationship intact.....


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## Thorim (Jan 19, 2015)

eberlej said:


> Problem solved! In short, it was a fuse. What made it difficult to find is that the German fuses have to be pulled and each one needs the continuity checked as a couple of you suggested. I started pulling them and checking with an ohm meter but found that process to be slow and cumbersome and thought I could tell by looking at the fusible strip visible on the top edge of the fuse. The JD service manager also advised to check each fuse but to use the built in continuity checker provided in the fuse panel. The 6420 has a fuse blank that when you touch the contacts with the key on, a horn will sound if the fuse is good. I used my leatherman to pulled them one at a time and in quick order went down the line. It turns out that the 30 amp mark "ELX" is important. That was the sweetest sound of silence I've heard in a while.
> 
> Now all is well and thanks for the help.


Glad you got it fixed with out to much trouble, one of the worst feelings in the world is knowing you might have fried a friends expensive piece of equipment


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## Bonfire (Oct 21, 2012)

Sweet sound of silence, huh. lol. Glad you got it fixed.


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