Z125SKH won't start

[Waimea Mike]

Working on Kubota zero turn for a friend. Z125SKH serial 10740. Really strange issue I can't figure out. Turn key to start, you hear the start solenoid pick up but starter not powering up. I can short across the main terminals and starter engages. Put a voltage tester to either solenoid ignition terminal with key in start position and I get 12v. Put battery power across solenoid ignition terminals (not the main terminals from battery or to starter) and the starter picks up. The seat switch is closed. Solenoid tests good out of the machine, 0 ohms across main contacts with 12 applied across ignition terminals. I tried another solenoid with same results. Is there a diode or something else that is causing this? Couldn't find exact wiring diagram but the doagram I did find shows a diode in the solenoid ignition wiring. Don't see any diode anywhere. Where is the diode if there is supposed to be one? What am I missing?

 

[Russell King]

Sounds like there are some resistances to the amp flow through the starter solenoid fire wire (attached to the spade terminal of the solenoid). I think that is caused by corrosion in the safety switches, connections and wires. You can try to solve it by cleaning or replacing the safety switches. Or you can install a relay that is fired off by the existing wire and then closes and provides power from the positive cable (on starter) to the solenoid. (Just like you are probably doing).

Post #11 in this thread shows the added relay.

Fix for my G1800 with intermittent starter click but wont crank issue, probably applies to G1900 G2000 and others

I have seen people asking about this sometimes will crank and sometimes it wont but never a fix posted, that I saw. Mine would always crank with a jump or after a battery charge and would run and operate normally once started. Turns the connectors out of the alternator had developed resistance...

www.orangetractortalks.com

John Deere has a complete kit to install this, simple but expensive

John Deere Starting Improvement Relay Kit - AM107421

www.greenpartstore.com

You can find similar parts or kits on the internet (probably).

 

[whitetiger]

The wiring schematics for this model are in the Electrical wiring diagrams sticky thread.
The Sticky Threads are the first threads on the Service, Repair & Maintenance page.

 

[Mark Robke]

I am just trying to clarify. Twice you said ignition terminals on the solenoid, but there should only be one, just the small wire, which gets voltage from the key switch when in the crank position, activating the solenoid. One large terminal on the solenoid should have battery voltage with nothing on, with no voltage at the other one, then when the solenoid is activated, by the key sending volts to the small terminal, the 2 large terminals should have bat volts. The second large terminal on the solenoid connects to starter motor. Is this when you have bat volts on both large solenoid terminals, but it does not crank? But you can short the 2 large terminals, and it will crank? Russel probably has it right, but I was trying to figure out if the small terminal was activating the solenoid with full voltage. As far as a diode, they are in the circuit to prevent back feed to the key when the solenoid circuit collapses, so the terminals inside the key last longer. It is a 1-way check valve in the electrical circuit, so it could have resistance. I don't where it is though, Mark.

 

[lugbolt]

Brake switch failure will do exactly what you're describing. Every time! You can hear the solenoid clack but it doesn't really work...

solenoid is separate from the starter, it's technically a "starter relay".