Request for assistance, Kubota M105S starter motor will not turn over

[ckbrownla]

Hello everybody,

Thanks for taking the time to read this.:newhere:

The starter motor will not turn over until you jump across the starter solenoid switch lugs.
If the key-switch is in "ON", the engine will start and run until you turn the key off. :thumbdown:


In the Kubota M105S Workshop Manual, with a date code of "KiSC issued 03, 2007 A", there is a
section labeled "MECHANISM". In this section is a diagram labeled "3. STARTING SYSTEM",
[1] SYSTEM OUTLINE AND ELECTRICAL CIRCUIT
(1) System Outline.
The page number is 9-M12 in this manual.

This diagram appears to describe and label all the parts needed for the starter circuit of the engine.

However there is mention in a section labeled "SERVICING". And on page 9-S1 there is a chart in
a sub-section labeled "1. TROUBLESHOOTING". In a sub-sub-section labeled "STARTING SYSTEM" it
describes some problems that might cause the starter motor to not operate. The fourth item lists
a defective Monitor switch. Now, I have looked all over this workshop manual and have found
mention of this switch in locations usually associated with the Swing Shift. The photograph on
page 9-S21 appears to imply that there two such switches, one for HI speed and the other for
Low speed. I have looked through the "STARTING SYSTEM" section and this switch or switches do
not appear on this diagram unless the Monitor switch is made up of "(5) Safety Switch (1-2
Speed Change Monitor) and (6) Safety Switch (3-4 Speed Change Monitor)". I have no proof of
that nor do I believe that.

So where is the Monitor Switch mentioned above? I found it listed in a diagram located in a section
labeled "MECHANISM", sub-section labeled "[3] SWING SHIFT". The diagram is labeled "Electrical Device"
and this is found on page 3-M6. I looked at this diagram and could not find any Monitor switch(s) labeled.
The only ones that it might be are labeled "(4) LO Motion Switch" and "(5) HI Motion Switch".
However, there is no connection indicated to the STARTING SYSTEM :confused3:

I have seen that the "(11) PTO Safety Switch" located and understand that it prevents the "(12) PTO Relay"
from closing and supplying a ground to the "(4) Starter Relay". So no starting unless the PTO lever is in
the neutral or off position.


I can not figure a way to test the starting system if I can not locate these switches. To add insult
to injury, I know that the transmission must have the Neutral switch(es) made to allow the starter motor
to be activated. I can not locate any switch(es) labeled Neutral. It is possible that the Neutral
switch is a assembly of switches made up of "(5) Safety Switch (1-2 Speed Change Monitor) and (6)
Safety Switch (3-4 Speed Change Monitor)". I have no proof of that but that might make sense.

My manual has a identification number of W1013561 on many of the pages.
If anybody wants a copy of this manual, I can tell you where I got it from the Web.

Any help will be appreciated!!!!
Thanks in advance!!
ckbrownla

 

[Clint S]

Do you have power to the small wire (one that energizes the solenoid) when you cycle the key? That's where to start

 

[100 td]

I have no proof of that nor do I believe that.

WORKSHOP MANUAL TRACTOR M105S Code No.9Y011-13350 from Download Kubota M1�5S Workshop Manual
Have a look at page 9-S22 (468 of 561 pdf) for location and testing of the 1-2 & 3-4 Safety Switches, they are in the starting circuit, previous page shows the PTO switch location and testing as well. That should sort your starting circuit out.
EDIT: And while there may be discrepancies in the manual, "believe it" for 99.99% of it.

 

[rScotty]

Do you have power to the small wire (one that energizes the solenoid) when you cycle the key? That's where to start

Yes, that is where to start. If you do have power there when the switch is cycled then all the safety switches are OK. And sinceas you say - the starter motor works when you jump between the large starter starter solenoid switch lugs... Then the problem is just an internal contact problem and evidence that the solenoid itself needs replacing. Usually the starter itself is OK. This is a very common thing to have happen on all vehicles.

If you want, you can fix the solenoid yourself if it can be disassembled. Wthe solenoid does when actuated is to move a rod which shorts between the starter solemoid switch lugs from the inside - thus completing the high amp circuit that turns the starter motor. Those inside lugs and rods become arc-burned in time and need to be cleaned and filed smooth again. It's a very simple repair job if you want to do it yourself. Usually it's easiest to take the starter and solenoid off as a packeage. Then you can clean both and put some lube on the engaging gears as well.
rScotty