I realize you have ongoing problems with safety switches. Check voltage as I stated earlier. If low voltage is the issue, there is an easy fix.
ZD 28 Bypass Help!
- Thread starter amosmandy
- Start date
GreensvilleJay
Well-known member
Equipment
BX23-S,57 A-C D-14,58 A-C D-14, 57 A-C D-14,tiller,cults,Millcreek 25G spreader,
thanks to Dusty for this...
The switches have to be in one position to start the engine and in the opposite position for operation. \
...
So the simple 'bypass with jumpers ' option will NOT work, don't even try,waste of time and material
Dang 'computer boxes' make like interesting(aka FRUSTRATING !!!)
6 acres is a lot of grass to cut, so I'm wondering if the problem are the actual switches failing due to wet grass and gorf' or corroded wires and /or connections.
According to the diagram pin 2 of the 'box' should have 12 volts when the L+R arms are in the 'safe' or 'start' position. Easy to test.
Another possible problem is the arms aren't 'home',so switches don't supply power. Again 6 acres can be a LOT of bouncing and jiggling which can be rough on wires and connectors. I'd expect everything to be well secured to not allow connectors to come off or 'kinda off'( that 'random' works/don't work PITA problem....)
In the 'real world', I'd be using some form of hermetically sealed switch, impervious to dust,dampness,grass, etc.
The switches have to be in one position to start the engine and in the opposite position for operation. \
...
So the simple 'bypass with jumpers ' option will NOT work, don't even try,waste of time and material
Dang 'computer boxes' make like interesting(aka FRUSTRATING !!!)
6 acres is a lot of grass to cut, so I'm wondering if the problem are the actual switches failing due to wet grass and gorf' or corroded wires and /or connections.
According to the diagram pin 2 of the 'box' should have 12 volts when the L+R arms are in the 'safe' or 'start' position. Easy to test.
Another possible problem is the arms aren't 'home',so switches don't supply power. Again 6 acres can be a LOT of bouncing and jiggling which can be rough on wires and connectors. I'd expect everything to be well secured to not allow connectors to come off or 'kinda off'( that 'random' works/don't work PITA problem....)
In the 'real world', I'd be using some form of hermetically sealed switch, impervious to dust,dampness,grass, etc.
I've been down the road I believe amosmandy is on. Have to wiggle levers, etc. to try to get it to start. The very common issue is the contacts on the switches degrade to the point there is too much accumulated resistance through the 5 switches and the start solenoid doesn't receive high enough voltage to engage.
Mine was only seeing about 11.5 volts and that wasn't enough. Doing the relay mod has been working for me for 5 or so years now. I have also done the mod to my BX22 for the same reason.
Attachments
Solid state relays work extremely well for these types of mods. They draw almost no control current so even severely degraded switch contacts will control them. The solid state relay is water and vibration proof unlike typical mechanical relays.
I have used a number of these relays in restoring vintage radios where the power switch is part of a complex multi-pole switch used for multiple functions for which the only replacement would have to come from another parts unit.
This Hallicrafters "Sky Rider Diversity" from 1937 is a good example. It uses a complex push button switch that chooses the frequency from one of six ranges while also turning the power on or off. The switch was custom made by Yaxley for this very small production run (the radio cost considerably more than most new cars of the Great Depression era) and the switch extends the full depth of the receiver and has over 200 individual contacts. It is difficult to repair and impossible to replace. The audio section (with its dedicated power supply) and the power supply for the rest of the receiver sit on two separate chassis that slide inside the floor stand/bass reflex speaker cabinet; each has a small solid state relay hidden on the underside of its chassis quietly taking the load off the power control contacts of the complex range switch.
This receiver is now complete except for replacement authentic grill cloth which is coming from a European supplier, the race is on to see whether it or my new Kubota F2690 and deck make it here first
At this point, since it appears the drought may be easing I hope the Kubota front mount mower wins the race!Rodger
GreensvilleJay
Well-known member
Equipment
BX23-S,57 A-C D-14,58 A-C D-14, 57 A-C D-14,tiller,cults,Millcreek 25G spreader,
How many hours on this machine? It is obvious that you don't have the mechanical ability to do the modifications to the machine that you want, so the next best thing to do is either have the dealer repair it for you or buy a new machine. 6 acres a week is a lot of cutting, and you should have a commercial machine that was designed for this type of work and sell it when it gets 1500 / 2000 hours on it and it still has some trade-in value.
A ZD is a commercial mower. I agree that 6 acres a week would be a lot of mowing and the mower likely has quite a few hours, but it is a diesel and should run 4 or 5000 hours if taken care of.
You may be correct on his mechanical abilities. I'm hoping he can check the voltage at the start solenoid.
If low voltage is the problem the relay mod is pretty simple to install.
Thanks
It is the only time Minerva cat will get near it because when I get the replacement grill cloth, it would probably be too tempting for her claws!Rodger
Yes, the engine should run a great number of hours if properly maintained, however, there is a lot more to a ZTR than just the engine, and those parts do wear, and can and do create their own issues. As an old farmer once told me, being a farmer isn't enough, you need to be well versed in veterinary care, and be a good mechanic to keep all the farm machinery working the way it was designed to be. If you don't have the skills that are necessary to repair your own equipment, then you are doomed to pay someone else that does. I would suggest that you purchase a factory shop manual for your particular machine, and start reading it. Sometimes you will need to read it a few times just to digest what is on the printed page, and there is nothing to be ashamed of when you do that. I was a mechanic in my younger days, and technology overtook my skills. I can still work on things that are mechanical, but when it comes to complicated electronics, I am at a loss and have to defer to the younger generation that understands the principles of modern technology. If I owned your machine, I would start by looking for any wear in any of the functions that move, such as the handles. If there is slop in those, you have to eliminate that slop before you can make the adjustments to the switches.
I own a Corvair with a 4-speed transmission, and the shifter developed problems. Being that I understand how the shifter transmits the motion to the transmission, I was able to find the root cause of the problem. It was both a pin that had developed wear in it and the fact that the hole that the pin goes through had also worn. It now shifts as it did back in 1964 because I remove all the wear that it had accumulated over 50+ years. Knowing where to look is half the battle to get any machine back to its "like new" performance.
I own a ZD so I know a little about them. It's a solid machine. How it's used or abused, maintenance, and luck will determine how long it can last. Mine has 1650 hours. It was bought used with about 1500 hours on it. I mow about 3 acres, some of it pretty rough. Here in the high desert I only mow 3 -5 times depending on rain, so I'll never wear it out.
Thanks for the replies. I have maintained the machine as well as possible, but it does take a beating. I bought it new in I think 2006-2008.
I have taken it to the dealer when the switches malfunction as I have stated at least 6-7 times. Sometimes it takes 4 weeks to get it back from repair.
Again, at this moment the brake lever has to be jerked around to start.
I will check the hours on it and post and if I can check the voltage.
Ken
I have taken it to the dealer when the switches malfunction as I have stated at least 6-7 times. Sometimes it takes 4 weeks to get it back from repair.
Again, at this moment the brake lever has to be jerked around to start.
I will check the hours on it and post and if I can check the voltage.
Ken
So, I just checked the hour meter, and it has 1140 hours on it. It is a 72" ZD 28HP and to replace it today would be in the neighborhood of $20,000+.
And, as I have mentioned the dealer for my area has taken up to 4 weeks to replace a defective switch because they are always backed up in the service dept.
Ken
And, as I have mentioned the dealer for my area has taken up to 4 weeks to replace a defective switch because they are always backed up in the service dept.
Ken
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That's 500 fewer hours than my ZD21. I would have guessed you had more than mine. I'm betting the low voltage relay mod would solve your problems but the voltage reading would confirm that.
GreensvilleJay
Well-known member
Equipment
BX23-S,57 A-C D-14,58 A-C D-14, 57 A-C D-14,tiller,cults,Millcreek 25G spreader,
There are only two 'safety switches', the ones on the left + right handles or arms ( whatever ZT control levers levers are called ).
Having them replaced 6 or 7 times is a huge 'red flag' for me. was only one replaced(say left side arm) or both ? Was any proper inspection of the wiring done ? Did you keep those switches ?
It's really hard to believe a group of switches ,designed for that purpose, could all fail .
It'd be interesting to know the part number and see if other mowers.tractors use them , do they fail ?
Also , I don't see how the 'low voltage relay mod' would actually work on this machine as the 2 switches are only connected between +12 and the 'combination box' ...NOT directly connected to the starter relay.
Now they could be replaced with 'reed switches and magnets'. Those are impervious to dust,dirt,water,etc. A 'low tech' solution, commonly used on door switches for home alarm panels. High tech would be 'hall effect' switches. Either upgrade would be more reliable BUT if the OEM switches WERE a problem, surely more people would be complaining ?
Having them replaced 6 or 7 times is a huge 'red flag' for me. was only one replaced(say left side arm) or both ? Was any proper inspection of the wiring done ? Did you keep those switches ?
It's really hard to believe a group of switches ,designed for that purpose, could all fail .
It'd be interesting to know the part number and see if other mowers.tractors use them , do they fail ?
Also , I don't see how the 'low voltage relay mod' would actually work on this machine as the 2 switches are only connected between +12 and the 'combination box' ...NOT directly connected to the starter relay.
Now they could be replaced with 'reed switches and magnets'. Those are impervious to dust,dirt,water,etc. A 'low tech' solution, commonly used on door switches for home alarm panels. High tech would be 'hall effect' switches. Either upgrade would be more reliable BUT if the OEM switches WERE a problem, surely more people would be complaining ?
There are five. One each on the R and L levers, one on the mower clutch, one on the brake, and the seat switch. This is a mod that has been performed on many BXs and ZDs, among others. If you Google "John Deere Low Voltage Start Relay" you will find lots of reading. It works.
GreensvilleJay
Well-known member
Equipment
BX23-S,57 A-C D-14,58 A-C D-14, 57 A-C D-14,tiller,cults,Millcreek 25G spreader,
I believe the JD bodge is for the 5 switches that are all in series, like old Xmas lights were. The OP rider has PTO, brake, seat switches individually going to the 'combination box, as well as the R+L levers(those are in series) which doesn't allow for the JD bodge to be a 'fix'. I did it to a JD140 ,decades ago.
It's also unclear WHICH of the switches have failed. Repair bills should say exactly which ones were replaced. That information is very important.
What's interesting is that the WSM states...
"When the main switch is then turned to the START position with the safety switches on, the terminal 30 is
connected to the terminals 50 and AC. Consequently, battery current flows to the starter motor and start the engine" ....
So I suspect ONLY the safety switches are the problem.
Curiously, no mention of what condition the PTO, Brake or Seat switches have to be to start ! Common sense would say Brake ON, Seat OCCUPIED and PTO OFF, so only 1 of the 32 combinations SHOULD 'start' the machine.
It's also unclear WHICH of the switches have failed. Repair bills should say exactly which ones were replaced. That information is very important.
What's interesting is that the WSM states...
"When the main switch is then turned to the START position with the safety switches on, the terminal 30 is
connected to the terminals 50 and AC. Consequently, battery current flows to the starter motor and start the engine" ....
So I suspect ONLY the safety switches are the problem.
Curiously, no mention of what condition the PTO, Brake or Seat switches have to be to start ! Common sense would say Brake ON, Seat OCCUPIED and PTO OFF, so only 1 of the 32 combinations SHOULD 'start' the machine.
My ZD is a 2007, his is a 2006-2008 and I believe it is virtually the same machine with a bigger deck and engine. That mod cured my mower's safety switch issues. If he reports back with a below 12 volt reading to the start solenoid, for what ever reason, this mod will work for him. If he has no voltage there he has a misadjusted or defective safety switch or other issues. Since it works some of the times I doubt it will be anything else. When I was having my issues it seemed to be one switch and then next a different one. I believe moving levers, brake ect. was just improving a contact enough to work sometimes. Frustrating.
Since the mod it has never given another no start. You are free to believe what ever you want. My experience says it will work.
GreensvilleJay
Well-known member
Equipment
BX23-S,57 A-C D-14,58 A-C D-14, 57 A-C D-14,tiller,cults,Millcreek 25G spreader,
I'm basing my help on is the WSM from Kubotabooks.. website
from the cover page...
ZD18(F),ZD21(F),
ZD25F,ZD28(F)
WORKSHOP MANUAL
ZERO TURN MOWER
KiSC issued 04, 2009 A
and the wiring diagram in the electrical section,page 5-M1, PDF page #213.
If it's not the correct diagram,for his machine,then it'd be nice for someone to post the correct one or a 'link'.
from the cover page...
ZD18(F),ZD21(F),
ZD25F,ZD28(F)
WORKSHOP MANUAL
ZERO TURN MOWER
KiSC issued 04, 2009 A
and the wiring diagram in the electrical section,page 5-M1, PDF page #213.
If it's not the correct diagram,for his machine,then it'd be nice for someone to post the correct one or a 'link'.
I don't know if the design changed in later machines, but the earlier "combination box" uses mechanical relays in the box to control the glow plugs and the starter. The external safety switches are used in a simple low current logic circuit and if the correct combination of open and closed safety switches are read AND voltage is fed via the start contact on the starter switch, then the internal start relay in the combination box feeds voltage to the starter. The combination box allows the use of very low power switches as the safety switches, the downside of this is switch contacts (especially if the switch isn't sealed) are more likely to have contact build up preventing proper function when they aren't switching any significant power.
The best style of safety/sensing switch for this type of use is a hermetically sealed magnetically operated reed type switch which is reliable for several operator lifetime's worth of operation. They can't switch much current but they have incredible life in low power applications. The classic "tipping bucket" type rain gauges use this type of magnetic reed switch and they cycle 100 times for every inch of rain counted and do so reliably for decades. But I suspect Kubota is still using mechanical plunger style switches which are common and rugged but subject to contact failure which is why jiggling levers/treadle control or the seat often allows a start. As the contacts on a regular mechanical switch wear, adjustment of the switch location/actuation becomes more critical.
If the internal relay in the combination box has degraded contacts, then the added external relay will compensate for the voltage drop across the internal relay contacts allowing reliable actuation of the starter. The same issue can happen with the glow plug relay contacts in the combination box. I would think Kubota would have switched from mechanical to solid state relays in the later combination boxes but I only saw an early one while helping a local farmer troubleshoot a random no start condition.
Miniature relays with high current contacts don't age that well as manufacturers cut contact size to the bare minimum to shrink them. Last winter, one of my central heating systems had the blower fail to start followed by the over temp protector shutting down the burner. The control board (common to MANY brands of central heat/AC systems) has a large DPST 30 amp relay which supplies power to an accessory terminal (i.e. for use with a duct mounted humidifier) and simultaneously to a much smaller blower relay which controls the blower allowing for separate speeds for AC and heat. The blower relay contacts had failed and since I prefer for the blower to run at high speed both for heat and A/C (which does a better job with air filtering), I just moved the blower lead over to the main relay which is far more robust than the smaller relay.
Rodger
The best style of safety/sensing switch for this type of use is a hermetically sealed magnetically operated reed type switch which is reliable for several operator lifetime's worth of operation. They can't switch much current but they have incredible life in low power applications. The classic "tipping bucket" type rain gauges use this type of magnetic reed switch and they cycle 100 times for every inch of rain counted and do so reliably for decades. But I suspect Kubota is still using mechanical plunger style switches which are common and rugged but subject to contact failure which is why jiggling levers/treadle control or the seat often allows a start. As the contacts on a regular mechanical switch wear, adjustment of the switch location/actuation becomes more critical.
If the internal relay in the combination box has degraded contacts, then the added external relay will compensate for the voltage drop across the internal relay contacts allowing reliable actuation of the starter. The same issue can happen with the glow plug relay contacts in the combination box. I would think Kubota would have switched from mechanical to solid state relays in the later combination boxes but I only saw an early one while helping a local farmer troubleshoot a random no start condition.
Miniature relays with high current contacts don't age that well as manufacturers cut contact size to the bare minimum to shrink them. Last winter, one of my central heating systems had the blower fail to start followed by the over temp protector shutting down the burner. The control board (common to MANY brands of central heat/AC systems) has a large DPST 30 amp relay which supplies power to an accessory terminal (i.e. for use with a duct mounted humidifier) and simultaneously to a much smaller blower relay which controls the blower allowing for separate speeds for AC and heat. The blower relay contacts had failed and since I prefer for the blower to run at high speed both for heat and A/C (which does a better job with air filtering), I just moved the blower lead over to the main relay which is far more robust than the smaller relay.
Rodger
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