John Deere error code 15

Johndeere3720 · Aug 27, 2009

Well, this morning when my dad picked me up at my grandparents he was telling me that the 3720 wasnt driving. I guess he was feeding the horses and it suddenly stopped. Then the little computer on the dash said error code 15. He tried to get it to move but only went about 20'. The tractor runs fine though. He called John Deere and they were saying it was a computer glitch. They might come up today to work on it so I was going to take pictures for everyone. I also was wondering if anyone else had this problem? Also, the fuel guage hasnt worked in a long time so I wonder if code 15 played a part in this too. Comments welcome!

Cocre · Aug 27, 2009

Error code 15 on the JD 3x20 series is "Operator not in seat". Check the seat switch and seat switch wiring.

Johndeere3720 · Aug 27, 2009

Hmm, I'll look at it tonight.

Johndeere3720 · Aug 28, 2009

Well, the seat sensor wasnt the problem. We took it off the tractor and brought it to JohnDeere. The seat sensor was fine so we went back home and put the tractor on the trailer. It was pretty hard since the tractor wouldnt drive so our neighbor Fred came up with his truck and pulled the tractor onto the trailer. To get it on the trailer we jack knifed my dads truck with the trailer, tied a long chain to Freds truck and the FEL bucket and pulled it onto the tilt trailer. I did take pictures and will post them next week. We hauled the tractor to Fisher implement and the guys there unloaded it by pushing it off the trailer. then they pushed it into the shop with a forklift. The mechanic, Darren, quickly got to work. He took a copper wire and hooked it to the lower conection for the seat sensor. The tractor then was able to drive. So he pulled the wire connecting toe seat switch to the transmission and pulled off the plastic covering around the wire. The problem was found easily. One of the wires inside must have got pintched and snapped along with corroision wearing the wire away. He connected the wires back together, put the wire cover back on and connected it to the seat sensor and the transmission. Then he hopped on it and drove it around their equippment yard. Then we loaded it up and went to my dads store so I could unload 14 tons of wood pellets from a truck. I even got pictures of the fix so everyone could see it.

mcd176 · Aug 28, 2009

I'm glad it was a simple fix!

offthetrail · May 29, 2013

I am having similier problems with mine.....seemed to work sometimes but then the code 15 pops up. The tractor got rained on......so I blew the switch connections under the seat off. Ran and shifted fine for twenty minutes and then same problem.
What a pain to move 7000lbs. Of locked equipment!
Thanks for any advice!

Ken · May 29, 2013

Johndeere3720 said:
Well, this morning when my dad picked me up at my grandparents he was telling me that the 3720 wasnt driving. I guess he was feeding the horses and it suddenly stopped. Then the little computer on the dash said error code 15. He tried to get it to move but only went about 20'. The tractor runs fine though. He called John Deere and they were saying it was a computer glitch. They might come up today to work on it so I was going to take pictures for everyone. I also was wondering if anyone else had this problem? Also, the fuel guage hasnt worked in a long time so I wonder if code 15 played a part in this too. Comments welcome!

JK 3720
On your fuel guage problem . I'm thinking the engineers have lost the secret to a working level sensor. This is a problem to most all J.D. tractors.
I use a 5 gal. paint mixing stick marked at levels as to add or use for the day.

ken