I'm not sure that this forum deals with small oranges (Kubota T1600H)!!?? I need to know what's in the box - the electrical combination box - does anyone have an electrical schematic of that box? I have the wiring diagram from the factory manual but it simply ends the wires going into an blank box. My starter (B+ is present at the starter) solenoid is not hot when I turn the key to start, and the glow plug circuit is inop. Jim
T1600H electrical "combination box"????
- Thread starter jkfind
- Start date
jk welcome and we work on anything orange even green up here. I once ask that same question to the Southeast Regional Service Manager for Kubota in Swanee, GA ( Mr. Brown ) his answer way dumb founding to me 
He didn't really know from his answer. Since then, I have stripped one down to find an IC circuit full of Triacs, Capacitors, resistors and an big Transistor acting as a relay that sends out voltage to your Starter solenoid terminal. This circuit demands only a controlled current that is 100 times smaller than that needed by typical isolated solid state relays. It is ideal for battery-powered systems. Using a combination of a high current TRIAC and a very sensitive low current SCR, the circuit can control about 600 watts of power to load while providing full isolation and transient protection. Go figure Ohm Law, 50 amps is more than your raw battery current output. Hence, small current drawing micro switches are just dandy for a safety seat switch, PTO switch and brake switch that must be in their designed functionality ( you know N/O, N/C position switches) and reporting ( conducting current ) into the IC Circuit ( your Black Combination Box ) for satisfying all conditions for a safe start up. This was a $110.00 experiment that my local Dealer "sucked" up from me for a brand new one 'since it was defective.'
jk I don't know you from Adam but I'm telling you straight, you either buy one from Kubota or use this attached relay hoping your current combinaton box is not totally grounded and blowing your glow plug relay circuit to get Battery voltage to your starter solenoid or I will send you a one way shipping freight permit to send me your T1600H I love those little tractors!
Also look at the attachments for a push button remote switch you can use to start that little bugger hooked to your solenoid terminal and the starter (BAT+) terminal for a emergency start, just have the key in the on position, not start position so the Alternator will charge the battery while running. Good luck and let us know if box is good and your switch(s) are bad or wiring grounded, because anyone of them out of functionality will cause the Combo to be DOA and not complete the circuit for a safe start.
Well jk my Hella Relay diagram won't upload so just get a Hella 12V 4RD 960 388-22 relay from an aftermarket auto store and use the diagram with the relay to wire around the combination box for a key start or like I said ship me your tractor
He didn't really know from his answer. Since then, I have stripped one down to find an IC circuit full of Triacs, Capacitors, resistors and an big Transistor acting as a relay that sends out voltage to your Starter solenoid terminal. This circuit demands only a controlled current that is 100 times smaller than that needed by typical isolated solid state relays. It is ideal for battery-powered systems. Using a combination of a high current TRIAC and a very sensitive low current SCR, the circuit can control about 600 watts of power to load while providing full isolation and transient protection. Go figure Ohm Law, 50 amps is more than your raw battery current output. Hence, small current drawing micro switches are just dandy for a safety seat switch, PTO switch and brake switch that must be in their designed functionality ( you know N/O, N/C position switches) and reporting ( conducting current ) into the IC Circuit ( your Black Combination Box ) for satisfying all conditions for a safe start up. This was a $110.00 experiment that my local Dealer "sucked" up from me for a brand new one 'since it was defective.' jk I don't know you from Adam
but I'm telling you straight, you either buy one from Kubota or use this attached relay hoping your current combinaton box is not totally grounded and blowing your glow plug relay circuit to get Battery voltage to your starter solenoid or I will send you a one way shipping freight permit to send me your T1600H I love those little tractors! Also look at the attachments for a push button remote switch you can use to start that little bugger hooked to your solenoid terminal and the starter (BAT+) terminal for a emergency start,
just have the key in the on position, not start position so the Alternator will charge the battery while running. Good luck and let us know if box is good and your switch(s) are bad or wiring grounded, because anyone of them out of functionality will cause the Combo to be DOA and not complete the circuit for a safe start. Well jk my Hella Relay diagram won't upload so just get a Hella 12V 4RD 960 388-22 relay from an aftermarket auto store and use the diagram with the relay to wire around the combination box for a key start or like I said ship me your tractor
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Thanks, ob1kubota for your reply!!!!
Am I disconnecting the combo box and just wiring the relay into the starter system, or leaving the box connected and cutting the appropriate starter solenoid wires coming into the box? My glow plug circuit is also inop - I assume the trouble is also in the box! I checked the glow plugs - their fine. The key switch is fine, also each of the 3 safety switches. Jim
Am I disconnecting the combo box and just wiring the relay into the starter system, or leaving the box connected and cutting the appropriate starter solenoid wires coming into the box? My glow plug circuit is also inop - I assume the trouble is also in the box! I checked the glow plugs - their fine. The key switch is fine, also each of the 3 safety switches. Jim
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Jim let me know how it turns out I believe you can wire your glow plugs on the accessories side of the ignition switch like the old L Series fused through its own buss. You just have to remember to hold it to the left for five seconds to warm up. ( I let mine warm until the fuel gauge levels off ) Yes leave the box intact for the safety switches but use the relay to start the engine and then see what happens in the ignition 1 position as far as gauges go. Like I said its a great little tractor just give it some love!
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Welcome to the forums jk, and very nice reply as usual Ob1. To be clear, we deal in oranges big and small here.
Hi all, I am not trying to highjack your thread but there seems to be no way to PM you Obi1. I have just aquired one of these little T1600H tractors and it seems in v good shape but for the deck. Looking under it I was a little concerned with the pump set up as it is so different from my older G4200 tractor. Not near as heavy I am guessing but still seems to be a well made piece of equipment. Someone told me to check the output shaft bearing in the transaxle to be sure it is tight. I did do that and it appears good. I read on your post you love these so is it a goodie? I have to sell one or the other and I am torn between what I know (G4200) or the T. My old G is tired and rough but runs. This T is much more modern and in much better shape. I paid 800 for it, I am thinking that was a deal.
Looking online, it seems that I am not the only one to experience an inability to keystart a T1600H lawn tractor. After unsuccessfully searching for wiring diagrams which I hoped would help determine the reason I decided once again to go over everything in an attempt to determine what the problem was. I really did not want to have to pay an exorbitant amount for that magical combination electrical box that the Kubota repair man said needed replacing.
I am consequently posting this hopefully to help someone. Interfacing with this box are three safety switches designed to prevent accidental starting if a person is not sitting on the seat; the foot brake not engaged or the cutting head engaged. Each switch respectively is located under the seat behind a cover plate secured by four spring loaded bolts; on the back side of the chasis main frame where the foot brake pivots; and behind the dash where the cutter head lever pivots. If one malfunctions, the mower will not keystart.
What seems to be unique with these safety switches is that they only work as designed when slightly depressed and making connection across the paired wires connected to each. Each can be easily checked for continuity using a multimeter after being isolated from the wires leading to each. Failure of the switch to work may only be from incorrect adjustment. If one is found not to establish an electrical connection when the plunger is manually depressed, the internal contacts may be dirty. To hopefully get them working again, carefully remove the switch and the rubber dust boot over the plunger and allow a small amount of electrical contact cleaner to run down along the plunger into the sealed switch. Work the plunger a number of times while rotating and the switch will most likely work again.
Reinstall and adjust the switch so that it works as intended, finally checking with the multimeter before reconnecting the wires. If these switches are working, and the mower still will not keystart, then the problem may be the little black box. Even then, it can be by-passed by installing a simple spring-loaded push button starter switch between the starter positive battery terminal and the solenoid terminal. I had used this for some time before establishing why the keystart did not work.
The dash mounted ignition/starter switch can also be checked insitu, checking the four wires at the plastic plug closest to it. One wire supplies 12V; the other 3 will indicate 12V functionality as the switch is turned to On; Glow plugs and finally start position.
I am consequently posting this hopefully to help someone. Interfacing with this box are three safety switches designed to prevent accidental starting if a person is not sitting on the seat; the foot brake not engaged or the cutting head engaged. Each switch respectively is located under the seat behind a cover plate secured by four spring loaded bolts; on the back side of the chasis main frame where the foot brake pivots; and behind the dash where the cutter head lever pivots. If one malfunctions, the mower will not keystart.
What seems to be unique with these safety switches is that they only work as designed when slightly depressed and making connection across the paired wires connected to each. Each can be easily checked for continuity using a multimeter after being isolated from the wires leading to each. Failure of the switch to work may only be from incorrect adjustment. If one is found not to establish an electrical connection when the plunger is manually depressed, the internal contacts may be dirty. To hopefully get them working again, carefully remove the switch and the rubber dust boot over the plunger and allow a small amount of electrical contact cleaner to run down along the plunger into the sealed switch. Work the plunger a number of times while rotating and the switch will most likely work again.
Reinstall and adjust the switch so that it works as intended, finally checking with the multimeter before reconnecting the wires. If these switches are working, and the mower still will not keystart, then the problem may be the little black box. Even then, it can be by-passed by installing a simple spring-loaded push button starter switch between the starter positive battery terminal and the solenoid terminal. I had used this for some time before establishing why the keystart did not work.
The dash mounted ignition/starter switch can also be checked insitu, checking the four wires at the plastic plug closest to it. One wire supplies 12V; the other 3 will indicate 12V functionality as the switch is turned to On; Glow plugs and finally start position.
In my haste in posting previous comments above on the relationship between safety switches and the electrical combination box, I omitted to mention that the first problem which arose at less than 100 hours with my T1600H was a failure of the engine to stop when switching off the key. This may be of value to someone.
Unable to find a cause for this problem, I simply bypassed the key shut-off switch and that $700 over priced electrical combination box. The key switch did all that it should but somehow it seems to be the function of this electrical combination box to provide the necessary power to the solenoid* on the fuel shut-off unit as a result of the engine having been running and turned off. Not ever using the head lights, I simply used the “hot” wire from one of the headlights to supply the necessary current required to do this job and its switch was already there. One of the two headlights was disconnected and a wire with the appropriate end terminals inserted between the disconnected joiner and the fuel shut-off solenoid*. Note that the wire from the dash mounted key switch had to be first disconnected from the connector block located in close proximity to the solenoid* before being replaced by the new by-pass wire from the lights wire. Wrapping the two connectors on each end of your by-pass wire with electrical insulation tape may be necessary to prevent any chance of electrical shorting depending on the design of the terminals used.
Turning off the engine is then simply a matter of turning ON the headlight switch with the engine idling and the key switch still ON.. (The lights only work when the key switch is on.)
Once the engine has stopped, DO NOT forget to turn off the key switch or the light switch. Forgetting to turn OFF the light switch when it is used to “kill” the engine, keeps the fuel turned off preventing the engine from starting next time you want it to start.