Error Code 73

dconine · Sep 21, 2011

Got a 2011 John Deere 4520 cab with error code #73. The owners manual only shows 1-72. Any ideas what it might be? It is intermittent and comes on at various times. Everything seems to work normally, battery cables are clean & tight. I am hoping it is something that we can fix before the dealer has to pick it up.

ctlguy · Sep 21, 2011

engine starter motor relay - starter output is shorted to battery or open circuit.

dconine · Sep 23, 2011

Any suggestions on what to look for? I have checked the starter relay and the wires going to it and they appear to be OK. I have tried swapping the relays but the error still occurs. Wiring to the starter & key switch is OK as well. Never had any problem starting it, error always comes on while driving it. Maybe a loose wire someplace else inline?

wolfpack2 · Feb 20, 2014

Did you ever find the cause of the issue? My 4520 cab started doing the same thing today.

dconine · Feb 20, 2014

Yeah, it was the ground cables that bolt to the frame next to the battery. The paint had to be polished off for a better connection.

wolfpack2 · Feb 21, 2014

Thanks, I now know what I will be doing this weekend. I ran the tractor for a couple of hours tonight and never had an issue. I am beginning to wonder if it was water in one of the connections from all of the snow and ice that has been blowing into the machine while plowing that evaporated after running it Thursday.

wolfpack2 · Oct 19, 2014

It made it through the summer, now it's back. I cleaned the battery terminals and the frame connection, but still get error 73 if I turn on the lights and the blower at the same time. With all of the electrical items turned on, I still have 14.0 volts at the battery regardless of engine RPM, so I don't think I have a battery or alternator problem. Anybody got an idea as to what to check next?

wacummins · Oct 22, 2014

Yep sure do

Check the cab to the engine ground strap. If it's not that check the main cab ground point under the steering wheel console ( the other side of the ground strap connection) You can check the ground system by using your jumper cable to connect the battery ground to the cab ground point as a jumper and see if your error 73 stops, mine did then I found the strap problem.....

William....

wolfpack2 · Oct 23, 2014

Thank William. It was the strap. I removed it and cleaned both ends. The point where they connect to the block was still painted and they installed the fuel line retainer on top of the ground strap. As a result there was very little contact between the bolt and the strap (only the edge). Everything else was insulated. BAD design in my opinion. I ground off the paint, cleaned up the strap and re-installed then sprayed it with terminal protection grease to prevent corrosion. I also installed a 4GA wire from the cab to the same point that the battery ground cable attaches to the frame. No more ground problems.