Kubota HST safety switch problem

[radair]

So I've made some progress. The 5 amp fuse for the OPC is blowing. This link B3000 just died for no apparent reason - OrangeTractorTalks - Everything Kubota may be of some use for those in the future.

The problem I'm having now is I replace the fuse and the tractor starts right up. But as soon as I push on the HST pedal the fuse blows and it dies. I ran out of 5a fuses so put in a 10a and had the same result. I jumped the seat switch with a short piece of wire to no avail. There's a Kubota dealer just a few miles away so I'm going to get more fuses and see if they have any ideas.

Thanks for your help!

 

[k0ua]

So I've made some progress. The 5 amp fuse for the OPC is blowing. This link B3000 just died for no apparent reason - OrangeTractorTalks - Everything Kubota may be of some use for those in the future.

The problem I'm having now is I replace the fuse and the tractor starts right up. But as soon as I push on the HST pedal the fuse blows and it dies. I ran out of 5a fuses so put in a 10a and had the same result. I jumped the seat switch with a short piece of wire to no avail. There's a Kubota dealer just a few miles away so I'm going to get more fuses and see if they have any ideas.

Thanks for your help!

Ok, the hydro pedal has a safety switch too. Because you can come up out of your seat as long as the hydro pedal is NOT pressed and the engine won't die, Usually it starts a short timer but then you have to pull up the seat towards the steering wheel. At least that is how my old L3400 hst worked. SO likely you have a connection on the hydro pedal too. Look for possible chaffed wire going to ground? engine runs, push pedal, fuse blows because you have grounded out connection with switch... still need a schematic to confirm what are just guesses at this point. but it wouldn't hurt to examine and find this hst pedal switch and its associated wiring.

 

[radair]

Thanks James. That's what the guy at the dealership said too. Might be wet or corroded. It's probably the one on the pedal on the right side of the tranny. I took your advice and ordered a workshop manual while I was there.

 

[radair]

I crawled under and found the pedal switch and pressed the plunger with my thumb. The spring action felt a little crunchy so I cycled it a bunch of times and tried it again. This time all was working and no blown fuse. I got my work done and put the tractor in the garage. Probably a good time to order a new pedal switch...

Thanks for the help

 

[k0ua]

I crawled under and found the pedal switch and pressed the plunger with my thumb. The spring action felt a little crunchy so I cycled it a bunch of times and tried it again. This time all was working and no blown fuse. I got my work done and put the tractor in the garage. Probably a good time to order a new pedal switch...

Thanks for the help

yep, crunchy NOT good. Sounds like you found it and a replacement will likely be the cure.

 

[civilian]

So I have a 2007 B26TLB that just quit like someone turned the key off. Tractor will not restart. Seat switch has the plunger pushed in and taped. (Broke off from seat base.) Looked at the pedal switch. Seems like plunger is "in" when in the neutral position of the pedal. Moving pedal either direction allows the plunger to move out. Dealer suggested checking the 5amp fuse. Blown. He also suggested the HST or pedal switch may be going bad. Replaced fuse, tractor started. Worked for afew minutes then quit again. Replaced fuse again and restarted. Try to move and it quit. Dealer closed now. Pulled switch out so I could check contiinuity. Should it have continuity when the plunger is in or out. It has no continuity in either position. Can a wire be inserted to the prongs on the tractor side to run tractor? Yes I realize the potential to move when starting, but it would only be for the weekend. Thanks for the help. Jon

 

[Peter 315]

You can bypass it like you said ....

 

[civilian]

Thanks, I appreciated the quick response. Will try that tomorrow and see if that quits blowing the 5 amp fuse. By using the wire tells me when the switch plunger is depressed, I should have continiuty. Correct? Jon

 

[Peter 315]

Yes... When you have the switch out test it .....The 5 amp fuse is for the safety switch circuit , Could be a pinched wire somewhere..

 

[civilian]

Yes... When you have the switch out test it .....The 5 amp fuse is for the safety switch circuit , Could be a pinched wire somewhere..

Or a defective switch. Jon

 

[Peter 315]

Or a defective switch. Jon

Have to start somewhere.......

 

[radair]

Same problem I had. I replaced the pedal safety switch ($44) and all is well again. That was frustrating blowing those 5 amp fuses over and over again.

 

[civilian]

Well, I went out this morning to tackle my HST problems. First I made a jumper to remove the HDT switch. I will order new one tomorrow from dealer. Then I replaced the 5 amp fuse with a 5 amp circuit breaker. Starts right up. Ran it for a few hours today with no problems. Thanks for all the help here on TBN. Jon

 

[Fallon]

If you have to replace a fuse once, that's odd but not a problem I usually try to debug. If it blows a 2nd time, that's a problem & you can't chalk it up to a bad fuse. You really need to figure out the root cause.

A fuse is just a small wire that melts in a specific (safe) location. If you replace the fuse with a bigger one it may be a wire that melts down & burns your whatever (tractor, house) down.

In an OEM electrical system, a blown fuse generally means something is shorting to the frame in some direct or indirect manner. In a custom or modified electrical system it could be an overloaded circuit. But not in any modern reasonably well engineered vehicle.

Putting in a breaker or continually replacing fuses is asking for problems to show up somewhere other than the safety of the fuse box.

The only way a bad switch should blow a fuse is if it permits things to short to ground, which would be a little odd. High resistance due to a corroded or internally fried switch would generally cause high resistance. That would cause wierd not working issues but not increased amperage to blow a fuse. I'd suspect chafed wiring or something in that circuit creating a path to ground.

 

[civilian]

When I get the new HST switch, then I will go back to the fuse after looking for chafing. The dealer suggested the fuse may be blowing because of the bad switch. Jon

 

[radair]

If you have to replace a fuse once, that's odd but not a problem I usually try to debug. If it blows a 2nd time, that's a problem & you can't chalk it up to a bad fuse. You really need to figure out the root cause.

A fuse is just a small wire that melts in a specific (safe) location. If you replace the fuse with a bigger one it may be a wire that melts down & burns your whatever (tractor, house) down.

In an OEM electrical system, a blown fuse generally means something is shorting to the frame in some direct or indirect manner. In a custom or modified electrical system it could be an overloaded circuit. But not in any modern reasonably well engineered vehicle.

Putting in a breaker or continually replacing fuses is asking for problems to show up somewhere other than the safety of the fuse box.

The only way a bad switch should blow a fuse is if it permits things to short to ground, which would be a little odd. High resistance due to a corroded or internally fried switch would generally cause high resistance. That would cause wierd not working issues but not increased amperage to blow a fuse. I'd suspect chafed wiring or something in that circuit creating a path to ground.

I did diagnose it to the safety switch, but I was able to get it to work by cycling the plunger a few times, which felt kind of crunchy. While I was waiting for the switch to come in I went though another episode with the blown OPC fuse. Manually cycling did not work so great this time.

 

[civilian]

Went to the dealer and picked up a new HST pedal switch. Surprisingly it has continuity when the plunger is in. Old one had no contiuity in either position or from wire to outside threads. Installed new switch and tractor starts like it should. But my switch cost $49, not radair's $44. Grrr. Jon

 

[jless1]

I put the same new safety switch in about one year ago and had no further problems. Now I am back to the same old thing. Is there a way to clean it. Can't afford to drop $50.00 every year. I still have the old one too.

John

 

[kenmac]

I put the same new safety switch in about one year ago and had no further problems. Now I am back to the same old thing. Is there a way to clean it. Can't afford to drop $50.00 every year. I still have the old one too.

John

just do as I did. remove it. No more problems !!