Kubota L4600DT starting issue

[tammyemond]

I have a Kubota L4600DT sometimes it starts and sometimes it does nothing, no clicking, no gauges, nothing. When it does start sometimes it runs just fine and sometimes it dies shortly after starting. WE thought it was the ignition switch so we replaced that and it started a few times and now nothing again. Seat safety switch is tied down. Battery is good, starts right up when it does start. This is our livelihood so any suggestions would be greatly appreciated. Thank you in advance.

 

[Williy]

Check all your electrical connections and make sure your cables
are not corroded inside. Check to see if you have good fuel flow

willy

 

[Roadworthy]

I agree with Willy but I'd go a bit deeper. Remove the connectors from the battery and clean connectors and battery terminals thoroughly. Inspect connector ends for signs of corrosion. This can extend under the insulation. Replace cables on battery and tighten securely. If you can move them at all they're not tight. Follow the ground lead to the frame. Clean, inspect, and tighten. After all this is done we can talk about troubleshooting.

 

[tammyemond]

I agree with Willy but I'd go a bit deeper. Remove the connectors from the battery and clean connectors and battery terminals thoroughly. Inspect connector ends for signs of corrosion. This can extend under the insulation. Replace cables on battery and tighten securely. If you can move them at all they're not tight. Follow the ground lead to the frame. Clean, inspect, and tighten. After all this is done we can talk about troubleshooting.

We cleaned all the battery connections and the ground. We think it's the neutral switch. We have it jumped for now and it seems to be working but, since the problem is sporadic we aren't sure if that's the problem or not. I know a bad neutral switch would keep the engine from starting, but would it keep the gauges from working? We had thought it was the ignition switch because power wasn't going to the gauges. The same day I ordered the switch the tractor started and ran fine for 4 days with no issues, then day 5 it wouldn't start again. Received and installed switch and started a few times then nothing again. I'll order a neutral switch, but we can't afford to just keep ordering parts without knowing if it is the actual issue.

 

[Sid Post]

I will pull a parts diagram and look at the safety switches. You got the seat and the Neutral switch so, good start at fix but I bet there is another switch or two that could be your issue.

I am assuming it isn't a fuel problem because it sounds like the dash gauges are out as well when this happens.

I would chase the wires from the dash looking for a wiring rub or a mouse nibble on the insulation. You could have an intermittent short due to a wiring insulation issue.

 

[Roadworthy]

There may be seat and PTO switches as well. Try cleaning the connectors for the safety switches. Pull them off and put them on again. You could even use a bit of contact cleaner from a spray can then work the connectors off and on a couple times. Sometimes it's the way a connector is crimped onto the wire - some conductors may be broken and only making intermittent contact. Your problem may not be in the switch itself. I really hate intermittent electrical problems. They're always the worst to cure.

 

[tammyemond]

There may be seat and PTO switches as well. Try cleaning the connectors for the safety switches. Pull them off and put them on again. You could even use a bit of contact cleaner from a spray can then work the connectors off and on a couple times. Sometimes it's the way a connector is crimped onto the wire - some conductors may be broken and only making intermittent contact. Your problem may not be in the switch itself. I really hate intermittent electrical problems. They're always the worst to cure.

I've looked at the parts diagram and can only find the seat and neutral safety switches. The seat switch has been tied down for years because my husband is light and every time he turned around while backing the tractor would want to shut down. I hate intermittent problems too. Don't know if the replaced part fixed the problem or if it's just intermittently working. I had a truck once that wouldn't start in the morning, by the time I got it to the shop they couldn't find anything wrong. I finally told them to keep it over night and try first thing in the morning. It was a cracked distributor cap, it would draw moisture at night and dry out during the day.

 

[Williy]

I had a small dodge pickup and took it in to the dodge shop to
get it to run smoothly again. Mech could not find the problem
as the points were burnt up. The spark plug wires had so much
resistance the the juice wasn't leaving the distributor so burnt the
points. Should have just done the job myself!
It was under warranty so didn't want to stop that

willy

 

[tammyemond]

I will pull a parts diagram and look at the safety switches. You got the seat and the Neutral switch so, good start at fix but I bet there is another switch or two that could be your issue.

I am assuming it isn't a fuel problem because it sounds like the dash gauges are out as well when this happens.

I would chase the wires from the dash looking for a wiring rub or a mouse nibble on the insulation. You could have an intermittent short due to a wiring insulation issue.

I looked at the parts diagram and can only find a seat and neutral switch. We replaced the neutral switch and it's running again. I still don't know for sure if that was the problem. Would a neutral switch keep power from going to the gauges?

 

[JC-jetro]

I looked at the parts diagram and can only find a seat and neutral switch. We replaced the neutral switch and it's running again. I still don't know for sure if that was the problem. Would a neutral switch keep power from going to the gauges?

Netural switch is only in the starter circuit along with starter and main key switch circuit. It does not feed gauges.

 

[Sid Post]

I looked at the parts diagram and can only find a seat and neutral switch. We replaced the neutral switch and it's running again. I still don't know for sure if that was the problem. Would a neutral switch keep power from going to the gauges?

If I get up from the seat with the tractor in gear, the motor dies and the electrics are all off. If I sit down and catch the motor, things go back to normal.

 

[tammyemond]

Netural switch is only in the starter circuit along with starter and main key switch circuit. It does not feed gauges.

So does it keep power from going to the key switch, and therefore keep the power from going to the gauges?

 

[JC-jetro]

So does it keep power from going to the key switch, and therefore keep the power from going to the gauges?

In order to say it with certainty I need to look at the wiring diagram. I have factory repair manual for my MX-4700. If I get a chance I will look at it on Monday. I actually bought a L4600 DT but realized later it was not built in Japan. I then changed my order to Mx-4700. They have a lot of similarities . The key switch is always powered on but it routes power to gauges when you turn the switch on . In your vehicle when you turn the key on , instrument light will come on along with gauges and then next turn closes the start up relay to switch power to starter circuit. It is like that on my Ford 1700 also. I have not gone deep with my Kubota as I had no need to do it yet. Do you have a multi meter? that might come handy for diagnostics. Do you have WSM (WorkShop manual)for your Kubota?

 

[tammyemond]

In order to say it with certainty I need to look at the wiring diagram. I have factory repair manual for my MX-4700. If I get a chance I will look at it on Monday. I actually bought a L4600 DT but realized later it was not built in Japan. I then changed my order to Mx-4700. They have a lot of similarities . The key switch is always powered on but it routes power to gauges when you turn the switch on . In your vehicle when you turn the key on , instrument light will come on along with gauges and then next turn closes the start up relay to switch power to starter circuit. It is like that on my Ford 1700 also. I have not gone deep with my Kubota as I had no need to do it yet. Do you have a multi meter? that might come handy for diagnostics. Do you have WSM (WorkShop manual)for your Kubota?

No I don't have a workshop manual, and our cheap multi-meter doesn't work on the setting to check conductivity. I looked at the wiring diagram on Kubota Parts Lookup PartsByNet.com but I couldn't follow it. It is on two pages split between front and back and I couldn't identify the key switch. It looked like the wiring from the neutral switch went to the back lights. So I'm hoping it does kill all power otherwise we still have a problem that could rear it's nasty head at the most inopportune time.

 

[Williy]

Tammyemond can you print the sections of the diagram so you
can tape them together?

willy

 

[JC-jetro]

No I don't have a workshop manual, and our cheap multi-meter doesn't work on the setting to check conductivity. I looked at the wiring diagram on Kubota Parts Lookup PartsByNet.com but I couldn't follow it. It is on two pages split between front and back and I couldn't identify the key switch. It looked like the wiring from the neutral switch went to the back lights. So I'm hoping it does kill all power otherwise we still have a problem that could rear it's nasty head at the most inopportune time.

see if you can get a screen capture of the wiring and post it here for guys to takke a look at it. On the multi meter, what do you mean by conductivity, all wire and metal conduct. if you mean "short " or "open" in a wire then reading zero ohm means the wire is not broken and circuit has " continuity" . If your resistance aka Ohms is infinity then it means circuit is open or broken. You can make a test light with alligator clip to check voltage, close or open circuit just the same. Key switch , closes and opens the circuit. when you put the key in and turn one notch in your vehicle you will notice the oil pressure light illuminate. That is verification of intact circuit and as soon as engine is on the oil pressure would go fro normally closed to open, hence turning off the oil pressure light.

 

[tammyemond]

see if you can get a screen capture of the wiring and post it here for guys to takke a look at it. On the multi meter, what do you mean by conductivity, all wire and metal conduct. if you mean "short " or "open" in a wire then reading zero ohm means the wire is not broken and circuit has " continuity" . If your resistance aka Ohms is infinity then it means circuit is open or broken. You can make a test light with alligator clip to check voltage, close or open circuit just the same. Key switch , closes and opens the circuit. when you put the key in and turn one notch in your vehicle you will notice the oil pressure light illuminate. That is verification of intact circuit and as soon as engine is on the oil pressure would go fro normally closed to open, hence turning off the oil pressure light.

Sorry, I meant continuity not conductivity. Our multi-meter doesn't work on the Ohms setting or the setting specifically for continuity. The reading doesn't change between an open and a closed circuit. We need to get a new one or find the one my dad had.

 

[tammyemond]

see if you can get a screen capture of the wiring and post it here for guys to takke a look at it. On the multi meter, what do you mean by conductivity, all wire and metal conduct. if you mean "short " or "open" in a wire then reading zero ohm means the wire is not broken and circuit has " continuity" . If your resistance aka Ohms is infinity then it means circuit is open or broken. You can make a test light with alligator clip to check voltage, close or open circuit just the same. Key switch , closes and opens the circuit. when you put the key in and turn one notch in your vehicle you will notice the oil pressure light illuminate. That is verification of intact circuit and as soon as engine is on the oil pressure would go fro normally closed to open, hence turning off the oil pressure light.

 

[tammyemond]

Tammyemond can you print the sections of the diagram so you
can tape them together?

willy

I can, but I can't identify the ignition key switch.

 

[JC-jetro]

Tammy,

What you have there is not wiring diagram but it is wiring harness layout. It is good info to have but does not identify how circuits are made. Additionally if you have a list of item designator then it is difficult to identify what that block without index. Like on first screen capture 040,050 and 070 are all fuses but you would not know the rating or what circuit it is protecting. I will look at my WSM to see if I can find some useful info. Do you know the model # of your multi meter? I yet to see any multi meter that does not read ohm. That is the very basic whether it is a $5 Harbour Freight meter or $1000 RMS Fluke meter. Once you have ohms reading it can be used for checking continuity as well. I suggest you take a look at the link below. It will be helpful to diagnose and understand what's going on.