Issues with Z421 Zero Turn

[Lgaston99]

When we purchased the house we are in at the beginning of the year the previous owners left us the Z421 mower. When attempting to start the mower all I get is a clicking sound. I have tested the safety switches and starter relay and all seem to be functioning correctly. The issue seems to be that I am not getting the right logic to the trigger the starter relay.

With the switches removed and jumped, I am able to start the mower when touching one of the inner wires on the seat switch with one of the outer wires on seat switch. I have replaced the seat switch and still no joy. At a loss for next steps and would greatly appreciate suggestions as to where to look next.

The other problem I am having is that I cannot get the hydrostatic transmission to disengage. I have the unit in neutral and have pulled both leavers at the back to disengage, but am unable to get the unit to roll without significant effort.

Thank you in advance for assistance.

 

[lynnmor]

I have no experience with that machine, I’ll just say that you must be missing something at the seat switch.

Some zeros have a mechanical disconnect on the wheel motors to allow free-wheeling maybe you haven’t disengaged completely.

 

[Captain13]

As far as as the switches, the safety switch on the blade engage is prone to getting debris between te switch lever causing it to not start. Might be worthy checking that out.

Sounds like the control valves for the forward controls are stuck Causing it to only go forward. What does the fluid look like?

 

[Cop56]

When we purchased the house we are in at the beginning of the year the previous owners left us the Z421 mower. When attempting to start the mower all I get is a clicking sound. I have tested the safety switches and starter relay and all seem to be functioning correctly. The issue seems to be that I am not getting the right logic to the trigger the starter relay.

With the switches removed and jumped, I am able to start the mower when touching one of the inner wires on the seat switch with one of the outer wires on seat switch. I have replaced the seat switch and still no joy. At a loss for next steps and would greatly appreciate suggestions as to where to look next.

The other problem I am having is that I cannot get the hydrostatic transmission to disengage. I have the unit in neutral and have pulled both leavers at the back to disengage, but am unable to get the unit to roll without significant effort.

Thank you in advance for assistance.

Did you get it fixed? I have same mower just clicking. Works if I shor solenoid. But can’t find what’s bad.

 

[Alfred_2345]

The other problem I am having is that I cannot get the hydrostatic transmission to disengage. I have the unit in neutral and have pulled both leavers at the back to disengage, but am unable to get the unit to roll without significant effort.

Not sure what levers you are referring to. Found a YouTube video and it appears the Z421 uses HydroGear ZT-3600 drives. (YouTube can be helpful on getting basic info.)
There are "bypass arms" on each hydro drive unit. You can get the manual directly from Hydro Gear.

https://www.hydro-gear.com/wp-content/uploads/2023/03/BLN-0108_3400_3600_3800.pdf

If you intend to keep the mower, I recommend you get the owners manual and workshop manual if available. Messick's is a good place to get parts. https://www.messicks.com/vendor/kubota but you can get them at other dealers too. A lot of them have the Kubota parts diagrams by model.

 

[Mowbizz]

I have the Z422 which is the model with a suspension seat. I have tried to disengage the hydro motors as well (one rod on each side that you are supposed to “pull out” to disengage) but nothing happens when they are in the disengaged position. Cannot get the mower to move. I had an Exmark years ago that had the same “rods” to disengage and they worked.
Also bought a little craftsman tractor mower for my daughter and ut has a disengage rod that works also. Sun-ting-wong with the Kubota ZT mowers that the disengage rods do not work. Couldn’t see anything in that manual either.

 

[JasonW]

I have the Z422 which is the model with a suspension seat. I have tried to disengage the hydro motors as well (one rod on each side that you are supposed to “pull out” to disengage) but nothing happens when they are in the disengaged position. Cannot get the mower to move. I had an Exmark years ago that had the same “rods” to disengage and they worked.
Also bought a little craftsman tractor mower for my daughter and ut has a disengage rod that works also. Sun-ting-wong with the Kubota ZT mowers that the disengage rods do not work. Couldn’t see anything in that manual either.

Found this on page 40 in the manual.

 

[Mowbizz]

Found this on page 40 in the manual.
View attachment 108527

Thank you! I’ll try it again next time I mow