DK45 HST won't start

[kengreen]

With my Bobcat DK 45 HST, the gear shift lights won't come on and the engine won't start. I took out the potentiometer by removing seat and tested it. It seems to work OK going smoothly from about 20 ohms to 1850 ohms after cleaning the contacts. I reassembled it but the gear lights still don't come on. Any way to test the Pre Heat-Cruise module next to the potentiomenter? I would rather not order one and find out it is not the problem. Any other suggestions?

 

[ritcheyvs]

OK, I don't have a HST but I'd be inclined to check that the pot is sending thr correct voltage to the cruise unit. I don't have a DK HST manual but the EX HST manual says:

When the range shift sensor is moved to the
setting points (N(3.1 ± 0.3V), M(2.5 ± 0.3V),
N(1.9 ± 0.3V)), the N, M and N lamp flashes accordingly.

Maybe somebody with a real DK HST manual can verify these numbers.

So I'd check those voltages. Just because the pot runs smoothly does not guarantee that it provides the correct resistance/voltage to the cruise unit when in neutral. IMO, if the voltage to the cruise unit is correct and you get no neutral light and no crank, I'd suspect a bad cruise unit or a bad fuse feeding the cruise unit (there are 2) or a ground problem.

 

[kengreen]

I am not sure exactly where to test the voltages from the potentiometer. Do you want me to insert the VOM probe into one of the three wires that come out of the potentiometer molex connector using the tractor frame as ground or what?

 

[k0ua]

I am not sure exactly where to test the voltages from the potentiometer. Do you want me to insert the VOM probe into one of the three wires that come out of the potentiometer molex connector using the tractor frame as ground or what?

There is 5 volts applied to one side of the pot. and ground to the other side.. the wiper of the pot should move smoothly thru its range with a variable voltage as you move from ground to 5 volts. If you don't have 5 volts on the high side of the pot and ground on the other, then check the fuses or replace the module.

 

[kengreen]

with the key in on position, the vom measuring between the black and white wires coming out of the potentiometer gets 1.3V at L position and 3.7 at the H position. It jumps regularly with each change in position.

 

[ritcheyvs]

with the key in on position, the vom measuring between the black and white wires coming out of the potentiometer gets 1.3V at L position and 3.7 at the H position. It jumps regularly with each change in position.

That's good. But what did it read in the two neutral positions? Neutral is the issue, not high or low.

 

[k0ua]

with the key in on position, the vom measuring between the black and white wires coming out of the potentiometer gets 1.3V at L position and 3.7 at the H position. It jumps regularly with each change in position.

This seems right. If the cruise module is working correctly, the output pin 21 (it is on the second smaller of the two connectors. throws a ground thru a diode to the low side of the start relay coil. The wire color at the relay appears to be blue. I don't know where the diode is located but it is in series with the ground side (blue) of the start relay coil (start relay is first relay on firewall on the left as you view the tractor by standing in front of it.) If you ground this contact on the relay where the blue wire is with a jumper, and hit the starter it should rotate. Keep in mind the logic in the cruise module also checks the status of the PTO switch.. before it will throw this ground out to the start relay. I beelieve you mentioned no range lights on the display module, so this is looking like a cruise module failure.. But I would try the ground jumper to be sure before I bought that module. I am not sure how much they cost. By the way did you pull all of the molex connectors on the cruise module and inspect them? All clean and happy?

 

[k0ua]

At this point, you should really have the workshop manual so you can do your own tracing, and troubleshooting.

 

[SSdoxie]

Ken has been posting this on both Kioti and Bobcat forums. Below is the Bobcat schematic. I wanted him to check for proper inputs, but according his response on Bobcat forum the wire colors are not matching. It takes 12v power input from the 20a fuse (red/white wire) and secondary signal from the starter relay with key in start mode. schematic show that to be red/blue wire, but Ken mentions he has a sold red wire and a red/white wire.
Mu question is what should he see regarding voltage if any coming from the ground side of the Start relay through that diode.

Hope you guys can help out, I just want to make sure he is getting both inputs required.

View attachment CT440_CT445_CT450 6987079 enUS sm 01-14,electic schematic.pdf

 

[k0ua]

Ken has been posting this on both Kioti and Bobcat forums. Below is the Bobcat schematic. I wanted him to check for proper inputs, but according his response on Bobcat forum the wire colors are not matching. It takes 12v power input from the 20a fuse (red/white wire) and secondary signal from the starter relay with key in start mode. schematic show that to be red/blue wire, but Ken mentions he has a sold red wire and a red/white wire.
Mu question is what should he see regarding voltage if any coming from the ground side of the Start relay through that diode.

Hope you guys can help out, I just want to make sure he is getting both inputs required.

View attachment 389814

Dennis I would think he would have around 12 volt on the wire heading back to the cruise module thru the diode if the start section of the key switch was engaged. The voltage would go thru the start relay's coil and since the diode is forward biased, it should go right thru it with a .7 volt drop. But if the ground thrown by the cruise module is not there no appreciable current would flow in the coil and the coil would not be energized.