Join Date: May 2011
Re: B2910 Problems Starting - Problem Solved, Learned a Lot
Well, after learning how to remove the control panel, ignition switch and the black plastic shroud behind it, I found the problem, which had nothing to do with the ignition switch - and in the end I did not need to remove anything except the rear wheel to fix the problem. However after describing the real problem and the fix, I will also share what I learned about the dis-assembly and testing of the ignition switch for future reference for others who may have other problems that do require getting behind the cover panel to check on and replace other electrical and control parts.
First, the problem: as WAbota suspected in his case back in 2009, and Vic also suggested, it was indeed one of the safety interlock switches. In my case it was the interlock for the 2500 RPM PTO (for the belly mower). Although I had originally suspected this and thought I was testing for it by making sure the PTO lever was in the right position before trying to start the tractor, what I should have done but did not do was to actually put pressure on the PTO lever while turning the key to the start position. I did this after my panel removal and electrical testing of the ignition switch, which proved to be fine, and the tractor started right up. I then looked under the tractor to see where the interlock switch was, and it was immediately obvious that it was loose. It is visible but hard to get to without removing the left rear wheel. Once I did this it was a simple matter to adjust the two large nuts that hold the switch in position and then tighten them to lock the switch in the correct position. Voila! The tractor started right up.
However, I am actually happy I did the unnecessary dis-assembly, because I learned a lot about how the tractor is put together, how to get to things, how to test the ignition switch, etc. And, I learned how to override the interlock switches to start the tractor if necessary when one of the switches was causing a problem, to wit:
1) The control panel (the part with the gauges, lights and speedometer) pops out from the front with some prying from the sides of the back plastic "cover frame" that it is screwed onto. The cover frame has 5 spring clips - two one each side and one on the top - that hold it in place on the black plastic shroud, a.k.a. the "cover panel". But in addition to popping it out of the cover panel, you have to disconnect the speedometer cable to get it out far enough to actually work on things, like removing the ignition switch.
2) The ignition or starter switch is simply pushed into the cover panel from the back, and is held in place with a black plastic bezel that screws onto the switch, with a fiber washer in between. So you unscrew the bezel, take off the fiber washer, and then take the switch off from the back of the cover frame, working through the hole in the cover frame left where the control panel was removed. Then you remove the electrical connector from the ignition switch.
I tested the switch with an ohmmeter and it seemed to be doing what it was supposed to, though without electrical schematics I couldn't be sure. It has four contacts, one of which is a direct connection to the 12V battery. In the first, or Off, position there is no contact between the battery contact and any of the other 3 contacts. In the 2nd, or Run, position, there was continuity between the battery and one other contact. In the 3rd, or Glow Plug Pre-heat, position, there was also continuity between the battery and a third contact, presumably the one that goes to the glow-plug controller. And in the 4th, or Start, position there was continuity between the battery contact and all of the other 3 contacts, one of which is connected to a black & white wire that presumably goes to the starter after first passing through the safety interlock switches. To verify that it was noth the ignition switch, after removing the connector from the switch I tried "hot-wiring" the tractor by connecting wires from the battery contact on the connector to all of the other contacts. All lights went on (as they should have, and did with the key), but the starter did not move or click. That is the point at which I decided to look for the interlock switches and quickly found the one for the 2500 RPM PTO that was at fault.
3) Cover Panel Removal
Although in the end I did not need to remove the cover panel to remove and check the ignition switch, it was a good learning experience for future reference. To remove it, you remove one large Phillips screw on the top of the panel that hold it in place, and then remove the steering wheel (easy - first remove the pop-off plastic center cover with the Kubota name and remove the nut that holds the steering wheel on, and also remove the big plastic nut over the dust boot). Then you have to remove the throttle lever (first removing the roll pin holding it onto the shaft with a pin punch). Finally you take the shroud off after disconnecting cables that go the the headlight/turn signal switch and the hazard light switch.
Hope this is helpful to someone down the line. This site and forum has a wealth of good info and I wanted to contribute something myself to help others.
Last edited by clarksvilleal; 05-30-2011 at 08:53 AM.