4020 quit running

[TLD89]

Started plowing the other day and the 4020 (Onan) lost power do to a bad pto switch that grounded out and blow the 30-amp fuse.
I'm waiting for new switch. Now the starter won't engage. My question is not having a pto switch keep the tractor from turning over?

Terry

[JSinMO]

Unfortunately the short answer from me is I really don’t know. But I’m wondering if there is a safety switch that won’t let the starter receive power if it thinks the PTO is engaged? Might be worth looking in the technical library, not sure if we have a schematic here or not.

[myerslawnandgarden]

Yes, the PTO switch is included in the safety start circuit.

Bob

[DavidBarkey]

Started plowing the other day and the 4020 (Onan) lost power do to a bad pto switch that grounded out and blow the 30-amp fuse.
I'm waiting for new switch. Now the starter won't engage. My question is not having a pto switch keep the tractor from turning over?

Terry

Terry , when you say the starter will not engage . Do you mean the motor is turning but not turning engine over , or do you mean starter not doing anything at all ?

[TLD89]

Dave the motor is not doing anything at all. The dash lite indicates power (square box with lightning bolt).
I installed New PTO switch still no power. Checked continuity on wires to safety switches, ignition, seat, travel switch PTO. Also, checked the switches on the seat, 3-travel lever, seat, PTO lever switch on panel below seat.
When the tractor had blowen the fuse from bad PTO switch and rear taillight wire grounding out it started fine.

[myerslawnandgarden]

Only a shot in the dark, but the most common area for these models to have a bad electrical connection is at the plug on the back of the key switch. You didn't mention if the headlights work, but if every circuit is dead that's where I would start. Btw. the indicator light with the lightening bolt that you mention being lit only indicates the battery state of charge observed by the voltage sensor.

Bob

[ssmewing]

Bob is right. The PTO switch is a switch exclusively designed to work safely to make sure nothing happens unless the PTO switch says it can.

He is also right about the common hot terminal that literally gets hot over time. That means a new ignition switch is needed. The heat does two things. It burns the coating off the terminal, preventing it from corroding. I do not reuse the terminal block. I do replace the terminal end with only brand name professional terminal ends and crimped with forged and shaped crimpers that have the crimper section on the cutter side of the crimpers. You should be able to pull on the crimped end as hard as you can and fail to pull it off.

The second thing that is important is that the terminal gets hot, and that loosens the rivet holding the terminal to the ignition switch.

This has nothing to do with the PTO switch, except they both just happen over time. They are both still the best solution to just buy them from the dealer and ensure that you will have the right parts.

[TLD89]

Found the problem the PTO micro switch had a faulty connection.
Thank you for all the input.

[Harry]

Found the problem the PTO micro switch had a faulty connection.
Thank you for all the input.

Sometimes it’s the simplest thing. Harry