Kioti DK45S 4 x 4 electrical issues

[East Coaster]

Has anyone had issues with the diode across the 4X4 solenoid in Kioti tractors. I have an interesting intermittent problem with a 2006 DK45S. I have a fair amount of experience with electrical issues but this one does have me stumped. This started with the fuse blowing intermittently when in 4 wheel drive. If I unplug the solenoid, the fuse would still blow. I replaced the 4 X 4 switch as well.

A side note here, the solenoid shows 30 ohms, the dealers here could not tell me what impedance this coil should be. should anyone knows this value that would be great.

A second note. On this tractor the 4 wheel solenoid and the PTO are on separate fuses. So the PTO circuit should not be an issue.

This is what I have discovered. The fuse panel on this tractor is under the left side floorboard. I found that the plastic amour protecting the wires coming out of the fuse box had slipped back and the conductors of several wires were showing, including the 4 x 4 wires. After insulating these wires and confident the problem was solved, the next use of the 4 wheel drive blew another fuse. I tried another fuse to determine when this blew and if I lost the fuse with the solenoid unplugged. Yes, it blew however it did not blow immediately, I lost power within an hour.

At this point I was convinced I was chasing another bare wire. I disassembled the tractor so I could unwrap the harness. I did not find any issues with wiring. I have a schematic and knew there was a a connection to the indicator light on the instrument panel separate from the switch light mounted on the fender. I disconnected this circuit,on the switch side, for the reason when I was testing the circuit again I noticed this light flickering. If the problem was in the instrument panel I wanted to eliminate the circuit.
The intermittent problem still exists. There is a diode across the solenoid circuit. When cold, this diode tests correctly with a meter. In that it blocks the electrical flow in one direction and shows 0 resistance in the other.

My question is has anyone experienced issues with this diode when it heats up?

The other possibility I am considering is if the bared wires coming from the fuse panel are now undersized for the current load. although I do not see any sign of overheating.

I am at a loss with this one, it seems like an easy fix, however I have been at this for a while with little success.
Any suggestions would be appreciated.

 

[Roadworthy]

Your 30 ohm coil will draw about 2.5 amps (30/12). Coil impedance in not likely relevant in a DC circuit. If in doubt, change the diode. Its purpose is to damp a spark when the coil is energized. It may work fine for your tester and still not do it's job when called upon. It could be breaking down internally when full power is applied.

 

[justman777]

If the circuit still blows when the diode is taken out, I don't think it would be the diode. This is a bit beyond me, but it sounds an awful lot like you get a ground issue somewhere. I think you're on the right track with chasing your wires looking for where it's shorting out.