John Deere Z920M Fault Code—Help Please

rangerray

LawnSite Member
Location
Senatobia, MS
I have a fairly new John Deere Z920M mower with 261 hits on it and today while cutting one of my yards the PTO shut down. It was flashing a fault code of 3-4 (3 blinks, pause, 4 blinks). I could switch off the engine, then restart and mow as usual, but after a minute or two the same thing would happen.

The manual says under “Electrical System Fault Violations” that the 3-4 code “indicates that the output circuit from the vehicle control unit for the start circuit or the PTO circuit is shorted to the battery.” The remedy is to “inspect electrical harness for pinched, chafed, or frayed wires.”

I have checked all wiring and nothing seems to be out of order. Does anyone know what else I might try before I give up and carry it to a dealer? It’s still under warranty, but I have a yard to cut tomorrow.

Thanks in advance for typing or giving me a call at 662-562-2900
 

weeze

LawnSite Fanatic
could be a wire loose where it connects to the pto switch or something like that. sometimes the switches go bad too. could also be a clutch problem or wiring problem there.
 
OP
rangerray

rangerray

LawnSite Member
Location
Senatobia, MS
Thanks for the info. I pulled the control housing and checked the wiring underneath to switches and such. Everything was plugged in and tight with no broken or frayed wires.
 

weeze

LawnSite Fanatic
I would if I could.
it doesn't work at all right now? it may be a bad pto switch or something simple like that.

does the whole mower shut off or just the blades when it happens?

if it's just the blades then it's probably a bad pto switch. they make them so cheaply these days. swing by the dealer and ask them to give you one to see if that's what it is. if it works then you can get right back to mowing and it will be free under warranty. you can change it out yourself. it only takes about a minute or less.
 
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rangerray

rangerray

LawnSite Member
Location
Senatobia, MS
Just the blades shut off, followed by the fault code. The engine stays running, but I have to shut the engine down and restart to engage the PTO again. I can mow for a little bit, then it happens again.
 

Ridin' Green

LawnSite Fanatic
Location
Michigan
I am guessing you have a faulty PTO switch, but that's just my guess. The code that is flashing plus the fact that just the blades shut off........I'd check that first. It isn't hard to take out and look at, and if you have the right tools you can check it for current flow etc.
 
OP
rangerray

rangerray

LawnSite Member
Location
Senatobia, MS
I’ll probably just get a switch then and try it. My multimeter is shot, so it’ll be hard to test a switch that possibly only works intermittently.

Thanks for all of the replies!
 

weeze

LawnSite Fanatic
make sure you are pulling the switch all the way up as well. i got one and if you just pulled it like normal it wouldn't lock into the on position and if you hit a bump it would make it shut off. you had to really pull up on it to get it to lock and stay in the on position...at least at first until it got loosened up.
 

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