Command Pro CH740 only runs if you hold the key in START position

[glwilliams58]

Thanks for the insightful reply Fish. And I can always appreciate a good bowl of chili.

Thank you for the time you have taken to provide this information.

I picked up new key switch on the way home from work today, along with some 20amp fuses.
Replacing the key switch had no immediate effect on the problem. It does exactly what the old switch does. It still starts up nicely and runs until you let the key go back to the ON position, then it dies.

I also have a nice multi-meter. I have checked the two fuses below the console on the left side of the seat and they are both good.

Let me know what additional information will help you diagnose the issue.

Thanks,

GW

 

[glwilliams58]

Possibly a low oil pressure shutdown switch. On the CH series it is normally located in the valley between the cylinders, kinda under the carb. May try unplugging it and see what happens.

ILEngine----I have looked through the engine and parts diagrams and do not see a low oil pressure shutdown switch anywhere. I could be wrong, but I don't think this model has one.

GW

 

[Fish]

Sorry about the delay, our dsl was out county-wide yesterday, which is bad if you make money on e-bay..... So I'll probably be doing some catch-up today. Here is a link to the scag manual, which is very little help. I'll try to scare up a link to the Kohler link.

scag

 

[Fish]

Here is the manual for the engine, just go ahead and print out page 36 an 37, and maybe the info on testing below.

http://www.kohlerengines.com/onlinecatalog/pdf/sm_24_690_06.pdf

 

[glwilliams58]

No worries Fish. Thanks for the manual.
Just to bring you up to date on what I know.

1. The key start switch is good (replaced with a new one and it had no impact)
2. All of the safety switches (seat, brake, steering arms, mower) are in the safe position, allowing the motor to start.
3. The fuel solenoid is good (I took it out, grounded it and witnessed it activate when the key is turned to START and then deactivate when the key is turned to ON).

#3 above tells me that the START cycle appears to be fine at all points but that the ON/RUN cycle is shutting everything down.

Are there switches that are associated with only the ON/RUN cycle? As mentioned previously, I do have an oil pressure sensor on this machine.

Thanks,

GW

 

[Fish]

Sorry again, I now am working on the wiring in the kitchen.

Read the part that deals with the Smart Spark, and check the voltage going to the S.A.M. unit while cranking and when the key is released and see what that tells you.

 

[glwilliams58]

I have tested the power source to the SAM.

From the red power source that I disconnected from the SAM, while using the grounding screw, as well as the negative battery terminal I get the same results:
9.4v while in the START position.
0.0v while in the ON/RUN position.
0.0v while in the OFF position.

 

[Fish]

I have tested the power source to the SAM.

From the red power source that I disconnected from the SAM, while using the grounding screw, as well as the negative battery terminal I get the same results:
9.4v while in the START position.
0.0v while in the ON/RUN position.
0.0v while in the OFF position.

Sorry, I have been battling the powers of darkness.......

But this is the problem, so we need to run this down!!!!! Needs 12ish volts at the start and run position, so we need to follow the wires!

 

[Fish]

I am amazed that no one else has stepped in!!!!! At least with a bad guess...... But the SAM unit needs voltage while cranking
and when the key goes back to run, so it should be a straightforward rundown.......

 

[Fish]

Yes, the immediate guess was the keyswitch, but I tried to get you to hold off, as these S.A.M. units are nothing but trouble....