DK40SE no start...pulling my hair out now.....

[k0ua]

View attachment 573523

Since your meter is not autoranging, you need to start on the scale with the expected value of the component under test. Start a potentiometer test by testing the two outer legs. This will be the overall resistance. See that it is near the expected result by the schematic or value given in the literature. Then test each leg to the center leg which is the "wiper". See that the value changes as you move toward and further away from the fixed legs. There can be gaps and "dirty" spots in a potentiometer where the wiper does not make good contact with the substrate of the fixed resistance. You may not be able to see these rapid discontinuities with a digital meter very well. This is one reason to ALSO own an analog meter. They are much better for seeing this type of failure. A tech should own both digital and analog meters. And preferably more than one of each.

All that said, I assume you are satisfied that the pot is not the problem, especially as you stated that the Nuetral lamp was lit when the range selector was placed into neutral. The cruise control acts as an integrator that "reads" the variable voltage placed on the high side of the pot and the wiper of the pot than sends that voltage to the cruise control module which "integrates" the voltage level and decides if it is within the specifications and then sends its decision out thru a diode to the start relay low side. The high side of the start relay coil should have +12 volts on it from the ignition switch when in the start position. ( you should measure that) and, IF the ground is "thrown" thru the diode by the module the start relay coil will pick energize and the start relay contacts will send +12 volts to the starter solenoid on the side of the starter. Those contacts will engage and the high current will flow thru those contacts and spin the starter motor.

You can also apply a temporary jumper-ed ground on the start relay low side to prove that every thing from start relay and ignition switch start contact out to the starter solenoid and its contacts all work. This would bypass the decision tree of the module and the nuetral safety pot, and PTO safety switch.

The starter motor should crank, and at least you would know that all is well from the starter relay forward. This is what I would do. Look in your service manual to figure this out.

 

[k0ua]

If you can't figure this out, you can call me. PM me, and I will give you my phone number.

 

[MotorSeven]

James, once again I appreciate your expertise. I had a friend come over that is/was/retired an electrical engineer. We went over everything in the manual related to 'No Start' and all of it passed the test(s). He did comment on me swapping out relays with a new one(at least the two relays that are identical...the third one is new) and wondered if the relays are....'bonded' preventing a swap out of one from identifying a problem.

Anyway, we jumped the exciter wire to the solenoid and the tractor roared to life. Then I ran it up and down the pavement and everything works, pto/cruise/gear shift indicator. So in the end I am throwing in the towel and going to add a starter relay and a momentary push button to override the problem. I need my tractor, and I suspect a bad connector or chewed wire(cats not doing their dang job?) that I just don't have the time to trace.

I do wonder about the others here that have newer tractors that the EPA have polluted(pun intended) where are they going to be in 10 years and a thousand+ hrs and have 20 or 30 items on the 'no start' list? I mean my tractor is relatively simple and I could not identify the issue so I worry about the newer generation of tractors.

 

[gimmodog]

you don't need a relay just a push button momentary switch from hot to starter

 

[gimmodog]

you don't need a relay just a push button momentary switch from hot to starter, this is what I use

EEEKit 2A 12V Waterproof SPST Car Boat Track Power Switch Push Button Engine Starter - - Amazon.com

 

[k0ua]

I am guessing a likely flakey cruise module not throwing out the ground for the start relay. You could just wire the ground and dispense with the Neutral and PTO safety . But it is up to you. It could be connections with moisture in them, Although they are sealed pretty good on that module.

 

[MotorSeven]

you don't need a relay just a push button momentary switch from hot to starter, this is what I use

EEEKit 2A 12V Waterproof SPST Car Boat Track Power Switch Push Button Engine Starter - - Amazon.com

Thanks for the link Gim!

 

[MotorSeven]

You could just wire the ground and dispense with the Neutral and PTO safety.

James, can you elaborate on this? Easier than wiring in a momentary stater switch?

 

[k0ua]

James, can you elaborate on this? Easier than wiring in a momentary stater switch?

Throw a permanant ground on the low side of the coil of the starter relay (unplug the wire that is there now. Then when you apply +12 volts with the key switch in the start position, the starter relay will energise and throw 12 volts to the starter solenoid out on the body of the starter motor.

Downside is that the tractor will crank if in gear or neutral, and PTO engaged or not. In effect bypassing the PTO safety switch and the Nuetral Potentiometer/logic in the cruise module.

Being hydrostat it don't matter a lot that the tractor will crank with the range lever in a gear range. It still won't move UNLESS you have pressure on a motion pedal. The PTO is a bit more dangerous. IF you were stupid enough to crank it up while the PTO solenoid was engaged AND someone had an appendage under a rotary cutter lets say, it could be a problem. The safety devices were put on for a reason, to prevent the lowest common denominator of operator from hurting themselves or others.

 

[k0ua]

OR, you could keep working on it to try to narrow down the problem.