Gravely ZT50 electrical problem

[Topgun1739]

MACHINE: Gravely ZT50 [mdl. 915144]
PROBLEM: Will not start with normal procedure. Jumping from the battery to the starter starts the engine and it runs normally, but disengaging the hand brake or engaging the blade PTO kills the engine. Seat safety switch, hand brake switch and PTO switch have been removed and tested independently - all function as they should.
QUESTION: Could the problem be with the Start Relay, Key Switch or Starter Solenoid? If so, how do I test them?
Any suggestions or recommendations would be greatly appreciated.

 

[Honda Tech]

Sounds like you have a short in your main harness. Are you blowing fuses?

 

[Topgun1739]

Thanks for the response Honda Tech. The only fuse on the machine is a 30 amp between the battery and the key switch and it has never blown. Any other ideas would be appreciated.

 

[bertsmobile1]

you verify the solenoid by jumping 12V to the small terminal at the base That should cause the solenoid to energise & spin the starter.
You check the cranking circuit by reading the voltage on that wire
It should show 12 V when all of the controls are in the start position and you turn the key to start .
You test the relay by applying + & - to the terminals labeled 85 & 86 .
Some are polarity sensitive some are not so try it both ways , you should hear it go click
To be doubly sure hook an Ω meter to terminals 30 & 87 then 30 & 87a you should see it make & brake contact
You test the wiring by putting the controls is start mode then checking the plug
85 should be ground & 86 should go + 12V with the key in the start position .
The start relay turns the magneto on & off it does not crank the engine .

Go to Gravely and download the parts list for your mower
It should have the wiring diagram for you mower

 

[Topgun1739]

Thanks Bertsmobile1, that is great information. I'll test those components and let you know what I find.