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A friend’s Kubota zero turn (sorry, don’t yet know the model# or age but believe it’s likely at least a 60”) has intermittent starting issues. He asked me to look at it (I’m not a mechanic). He said he has to turn the switch to start a number of times before it will finally click and start. Also, the seat switch doesn’t always cut the motor when he rises off it with the blade in gear. I suggested checking all connections and grounds, starting with the new battery. I’m thinking a bad or loose connection, bad solenoid, bad switch, break in a wire or bad controller. Any suggestions on what and how to troubleshoot?

You give us very little info to even make a good guess. I’m guessing either a corroded or loose connection. Besti can recommend is follow this troubleshooting procedure and see what you find. Electrical troubleshooting is difficult even for an experienced technician, so you have your work cut out for you. If you post back you must give us model numbers, so we have something to base our guesses on.


Electrical problems can be very easy or very difficult, depending on four things.
1. How well you understand basic electricity.
2. What tools you have and know how to use.
3. How well you follow directions.
4. You don't overlook or assume anything and verify everything.

Remember we cannot see what you are doing. You are our eyes, ears and fingers in solving this problem. You must be as accurate as you can when you report back. The two basic tools we will ask you to use are a test light and a multi-meter. If you have an assistant when going through these tests it would be very helpful. These steps work the best when done in order, so please don't jump around. Now let's solve this problem.

First, check the fuse(s), check battery connections for corrosion (clean if necessary) and voltage - above 12.5 volts should be good. Check and make sure the chassis ground is clean and tight.

Second, check for power from the battery to one of the large terminals on the solenoid. One of the wires is connected directly to the battery and has power all the time so one of the large terminals should light a test light or show 12 volts on a meter at all times.

Third, check for power at the small terminal of the solenoid while depressing the clutch/brake pedal and holding the key in the start position (you may need an assistant to sit in the seat to override the safety switch). If your solenoid is a four wire solenoid, check both small wire terminals as one is ground and the other is power from the ignition switch. If your solenoid is a three wire solenoid, make sure the solenoid body is not corroded where it bolts to the chassis of the mower as this is your ground path back to the battery. If in doubt, remove the solenoid and clean the mounting area down to bare metal. If there is no power to the small terminal then your problem is most likely a safety switch, ignition switch or in the wiring.

Fourth, check for power on the other large terminal of the solenoid while holding the key in the start position (you may need an assistant to sit in the seat to override the safety switch).

Fifth, check for power at the starter while holding the key in the start position (assistant again).

Sixth, check your ground circuit back to the battery.

After you have gone through each of the above steps, let us know what happened when you did each step. At that point we will have great info to tell you how to proceed. Remember you are our eyes, ears, and fingers, so please be as accurate as possible.

Be as specific as possible with voltage readings as this will help diagnose your problem quicker. If you do not know how to perform the above checks, just ask and I will try to guide you through it. Youtube also has some videos and as you know a picture is worth a thousand words.

Thanks for the great detailed troubleshooting guide! He had some loose connections which I cleaned, sanded and tightened. Multimeter showed intermittent voltage from starter side terminal of solenoid. Replaced the solenoid and it cranked right up. Oddly, the seat cut-off switch started working correctly at the same time. He’s happy and I’m glad that it was an easy fix.

As a Service Manager for a major mfg service shop, This procedure is the best I have seen written in this forum for testing for an Intermittent Start issue. One thing that I did not see - and since you had stated there were seat switch issues was testing the seat switch. One fast test for the seat switch is to TEMPORARILY bypass the seat switch and try to recreate the issue. A failing seat switch can cause much of what you described. This is a TEST ONLY. NEVER EVER bypass the seat for normal use. It was interesting how many seat switches we found bypassed when equipment came in for service. That machine never left the shop without all safety switches in place and functioning..... They are there for a reason.

I never post how to bypass safety switches for a couple of reasons.
1. Electrical troubleshooting is hard enough to start with. Bypassing any components, especially safety, can very easily cause more problems.
2. They are SAFETY switches and many DIY guys use that info to permanently do so.
3. Don’t know the experience of the person reading the procedure. The switches may be NC or NO switches and they may not know which they have or how they work.

In 10 years of around 200 to 300 jobs a year I have replaced precisely 4 seat switches
I have put a screw in the plunger to alter the sensivity of them about 50 or so times, particularly on ZTR's .
Very few no start problems will be the seat switch as most of them are not in the starting circuit .
The No 1 problem is corrosion
Getting people to believe that almost invisible amount of corrosion is causing their problems is the hard part .

Probably 1 in 5 who come through the gate with an electrical problem will proudly announce that are mystified as they have bypassed the seat switch and it still won't start as if that is the only problem there can ever be .

Rivets said:

I never post how to bypass safety switches for a couple of reasons.
1. Electrical troubleshooting is hard enough to start with. Bypassing any components, especially safety, can very easily cause more problems.
2. They are SAFETY switches and many DIY guys use that info to permanently do so.
3. Don’t know the experience of the person reading the procedure. The switches may be NC or NO switches and they may not know which they have or how they work.

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me either and here is why

a shop local to me (not naming any names) was called to diagnose a customer's running condition on a small diesel tractor. It was a Kubota. Tech tells customer to bypass the seat switch to test, tells him exactly how to do it. Customer bypasses switch. It starts and runs. Great. He then mows his yard and around the pond bank. Then, mows up next to the creek and rolls the tractor. Wife said tractor gently rolled onto it's side and the operator was trying to kick himself away from it, in doing so kicked the blades of the cutter and lost both feet and most of the right leg below the knee, and all of the left leg was non-salvageable. Guy sues shop for telling him how to do it, and won.

Unfortunately that's how we are in this day and age. We have to protect ourselves if possible, particularly if you are a business or work for a business of any kind. People like to sue businesses and attorneys like for people to sue businesses because attorneys like money.

I can't say how much they collected if any, but I can tell you that one man is now incapacitated for the rest of his life because of a tiny piece of wire. I know them well. No amount of money will bring his feet and legs back but a shop could have prevented it. I know the shop owner. Or former shop owner.

I have bypassed safety switches before, for testing or working towards a diagnosis. You'd have to catch me dead first before i tell someone how to do it.

Tdj2591 said:

A friend’s Kubota zero turn (sorry, don’t yet know the model# or age but believe it’s likely at least a 60”) has intermittent starting issues. He asked me to look at it (I’m not a mechanic). He said he has to turn the switch to start a number of times before it will finally click and start. Also, the seat switch doesn’t always cut the motor when he rises off it with the blade in gear. I suggested checking all connections and grounds, starting with the new battery. I’m thinking a bad or loose connection, bad solenoid, bad switch, break in a wire or bad controller. Any suggestions on what and how to troubleshoot?

Click to expand...

It’s probably a safety switch in the seat or the transmission position sensor switch thinks the drive control arms are engaged. Or it’s the starting solenoid itself . You can bypass the safety position sensors and start it but I’m not going to say because if a person already had enough working knowledge to somewhat safely attempt it they would’ve already thought of It. The knowledge is only available to those who already know about it. Captain Jack Sparrow signing off. Thanks rivet you maybe just saved someone’s feet and legs today. Joking but kinda not.

I know people were are being jerks by not telling folks how to bypass safeties but there is valid reasons we don't. Here in my area in the last ten year two kids have severely injured. and one guy took out his wife's new car because a miss wired safety system.

Some OEM even will not let all us to even have the wiring schematics.

Bert I have replace a few dozen seat switches but nearly all were the ones that OEM run 12v through. A few were grounded versions but that mainly was from being simply worn out.

Ericcburson said:

It’s probably a safety switch in the seat or the transmission position sensor switch thinks the drive control arms are engaged. Or it’s the starting solenoid itself . You can bypass the safety position sensors and start it but I’m not going to say because if a person already had enough working knowledge to somewhat safely attempt it they would’ve already thought of It. The knowledge is only available to those who already know about it. Captain Jack Sparrow signing off. Thanks rivet you maybe just saved someone’s feet and legs today. Joking but kinda not.

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Very few mowers have the seat switch in the cranking circuit so failure to crank is rarely a seat problem unless you are on face book when it will magically always be the problem .
Think about it , techs have to start the engine to do servicing & testing .
All of them have the lap bars , parking brake & PTO in the cranking circuit
All of the safety switches are simple sliding contacts that are NO or NC
So using your multi meter you work out which way they are connected when the pin is in then either jumper the plug or leave the plug open.
If it still does not crank then you start to use longer jumpers to bypass the wiring between the plugs .
Some will be power circuits & some will be ground circuits
I usually pull the key switch plug & jump the B & S terminals first ( after checking B actually has power )
thus I can poke around till I hear the solenoid fire without needing to be triple jointed to get to the key .
Also remember a bad fuse or connection at the fuse box will also cause random no crank problems as the voltage to trip the solenoid passes through the fuse .
Bad fuses / fuse holders are the No 2 most common electrical problems, bad grounds being No 1 .
A bad main ground cable will also manifest itself as a no crank situation
As for saving feet, more people attempting to repair mowers get injured by the blades suddenly spinning than any other mower misuse but the blades lopping off your big toe because your feet had ended up under the deck and the blades went strait through your Nikes like a hot knife through butter ( good reason why leather is the only material to make shoes from ) does not make good TV so it is never reported .

One thing that kills me is the mowers I get in and people think they can install a battery and finger tighten the bolts. And then they can't figure out why their mower won't start. Or at best the battery won't stay charged.