520 h Electrical Wont start or crank fron the key

[DukeRooster 2]

520 H wont start or crank from the key no dash lights but it will turn over when i jump the starter directly.  I was mowing for 2 hours then it shut down. The double wire on the regulator rectifier has signs of heat damage. Chinese rectifier replaced last year i put a new ignition switch in still same no change. 

[squonk 41,171]

First thing I would check is the 9 pin molex connector on the right side by the fuse box . They corrode and melt from the battery fumes and muffler heat 

[953 nut 55,393]

With any electrical problem it is best to start with having the battery load tested, auto parts stores will do this for free. Also, clean and tighten ALL electrical connections including grounds. Fuses and fuse holders are located near the battery and can be subject to corrosion, they should be cleaned and inspected as well. As Mike said, the 9 Pin connector (it is white) could be the source of the problem.

[Ed Kennell 38,329]

What year is your 520?      My 1988 has a fuse at the front right side of the engine.    The fuse did not blow but the legs corroded so bad it lost contact. I replaced it with a sealed fuse holder.

 

 

                 Oh, and to the 

Edited August 18 by Ed Kennell

[noncritical 5]

Same thing just happened to mine I jumped the starter to mow the grass not sure where to start with on fixing

[Ed Kennell 38,329]

46 minutes ago, noncritical said:

Same thing just happened to mine I jumped the starter to mow the grass not sure where to start with on fixing

Well, you have some great suggestions above.   The good news is you know the problem is in the starting circuit. 

Download the wiring manual for your tractor. You will find the Starting, ignition, and charging circuits.

The starting circuit has fuses, safety switches, connectors,  battery, and a solenoid that could cause the no start.