Ignition switch or wiring harness - Kubota L3400 HST

[Hai]

I have done enough checking step by step to trouble shoot the non-run problem of my Kubota L3400HST. At this point I think either the main ignition switch or the wiring harness is faulty. How do I test the ignition switch and determine its condition? Many thanks in advance.

Pertinent info/test results: Battery good; engine cranking strong but would not run; no fuel coming to the injector lines; no voltage between either terminal of the connector (this connector runs to the stop solenoid and has 2 terminals) and ground when the key is at ON position; no click or movement of stop solenoid shaft when key turned to ON position or OFF position (solenoid was removed from engine.)

 

[MinnesotaEric]

back-probe the electrical connector looking for battery voltage ACC, Run, and Start and no battery voltage on off. A big, fat red wire is likely to be always hot and comes from the battery.

It is helpful to have access to a wiring diagram and a 12v test light.

HJave you checked your fuses and relays? You can use a known-working relay of the same size from a different circuit.

 

[Hai]

This is what I have done:
- Key turned to START position: engine cranking strong but would not start.
- All fuses are good. Battery good.
- Checked for fuel at various points - fuel was not coming to the injectors (Nuts and injector lines were loosen and key turned to START position - nothing came out)
- Key turned to ON position: no click sound from the fuel solenoid, no feel of any movement either (hand placed on solenoid)
- The wire at the solenoid was disconnected and tested for voltage. This wire comes from the ignition switch to the solenoid. There are 2 terminals on the plug of this wire. I measured the voltage between each terminal and ground - Zero voltage. This indicates to me either the ignition switch or the wire is faulty.
This is where I am. Need to test the switch next.

 

[Hai]

I have not checked the fuel stop solenoid relay. Not sure where it is located on the L3400 HST or if there is one. Does anyone know? Thanks.

 

[MinnesotaEric]

This is what I have done:
- Key turned to START position: engine cranking strong but would not start.
- All fuses are good. Battery good.
- Checked for fuel at various points - fuel was not coming to the injectors (Nuts and injector lines were loosen and key turned to START position - nothing came out)
- Key turned to ON position: no click sound from the fuel solenoid, no feel of any movement either (hand placed on solenoid)
- The wire at the solenoid was disconnected and tested for voltage. This wire comes from the ignition switch to the solenoid. There are 2 terminals on the plug of this wire. I measured the voltage between each terminal and ground - Zero voltage. This indicates to me either the ignition switch or the wire is faulty.
This is where I am. Need to test the switch next.

You tested this by turning the key to start?

Doesn't matter since you have no fuel.

Have you checked your neutral safety switch, brake switch, seat switch and any other nerfing switch designed for the safety of children, old dogs and forgetful people?

 

[Hai]

Not sure what you meant THIS in the line:
You tested this by turning the key to start?
The key was at the ON position when I checked for the voltage.
I just tested the ignition switch and it is fine. The man at the Kubota Parts said I should check the relay and all fuses.
I removed the instrument panel to look for the relay, there was nothing there, just wires coming together into a bigger bundle. All fuses in the little box near the clutch are fine (checked with multi-meter.)
Then I located 2 black boxes next to the battery on the left side. One box labeled Main 40A Key Stop 30A; the other box labeled Key Switch 40A. The 30A fuse in the Key Stop was blown. The other fuses are fine. Got a new 30A fuse put in. I turned the key to ON, no CLICK from the fuel stop solenoid. Key turned to START, engine still would not run. I tried to start 2, 3 times with no success. Very frustrating. What to do next??
According to the Kubota parts diagram website, there is a stop solenoid relay on the L3400 somewhere between the fuel tank and instrument panel. I will try to get to it tomorrow.
Kubota Tractor Corporation - Parts List

 

[Hai]

Eric, I forgot to mention that on the L3400 HST, if the neutral safety switch and other safety switches are not in the right position, the engine would not CRANK. My engine cranked but would not start. Hope to clarify the problem.

 

[MinnesotaEric]

Eric, I forgot to mention that on the L3400 HST, if the neutral safety switch and other safety switches are not in the right position, the engine would not CRANK. My engine cranked but would not start. Hope to clarify the problem.

Have you opened up the bleed screw on the fuel filter to bleed out any air? If not, do so and if so, locate the fuel shut-off relay and swap it with another relay of the same size from elsewhere on the tractor.

 

[Hai]

I tried to bleed the air out at the bleed screw as well as at the injector lines right above the injection pump. No fuel coming out, so it was determined that the shut off solenoid not working. There was no power to the solenoid when key turned to ON. Will recheck the voltage of this connector wire to the solenoid again, then check the stop solenoid relay.

 

[Hai]

I finally got it running. The cause was the poor contact between the plug and the solenoid terminals. But the trouble shooting process is very interesting and lengthy before I got to this point. I really appreciated all the help I received from the forum.

As of yesterday after I replaced the blown 30A fuse in the Key Stop box near the battery, I got power to the stop solenoid wire. Tractor would crank but not start, thinking the solenoid is bad and needs to be replaced. I removed the solenoid from the tractor and called one dealer near me to see if they could test the solenoid and if it's bad I would have to buy a new one. I was told that the solenoid has to be tested while on the tractor. Called another dealer, the tech told me to bring it in. He put the power from the portable battery to each terminal of the solenoid, the shaft jumped quickly - the solenoid works fine. They told me to start the tractor without the solenoid. That's what I did- tractor started immediately, so the fuel pump, injection pump work fine, and no air in the system. That pointed the cause to the connection at the solenoid. I scraped, sanded the terminals of both the plug and solenoid, squirted some WD40 Rust Release then cleaned for good measure. The tractor started immediately.
I felt so good.