PTO not engaging

[PTmowerMech]

13WQ93KP011 Super bronco

Running at full throttle, battery is charging over 13v. Getting about 14v in and out of the PTO with the switch pulled/on. (almost nothing when switch is off)
But it's not engaging. The ohms are 0.00 on the tractor. So I'm thinking it's just a bad PTO.
Is there anything else that needs to be checked before I make that call?

Also, can you check the ohms with the PTO on the tractor? Or does it being grounded to the crankshaft affect that reading?

 

[StarTech]

Hmmm. Are sure you engaging the clutch or just pulling the switch? To me engaging means it is clicking and trying to latch up.

But yes the PTO clutch field can check on the mower as it is normally an isolated winding. Across the field windings you need to have at least 1.7 ohms [with something like 3.5 ohms being closer to normal]. Anything below this indicates either a shorted or partially shorted field. Also check from either one the field terminals and frame ground should be an open circuit if not then there is a short to ground. If you indeed getting 12V in and out then the grounding relay is fried or you have bad wiring or bad ground.

See schematic below.

 

[PTmowerMech]

Hmmm. Are sure you engaging the clutch or just pulling the switch? To me engaging means it is clicking and trying to latch up.

But yes the PTO clutch field can check on the mower as it is normally an isolated winding. Across the field windings you need to have at least 1.7 ohms [with something like 3.5 ohms being closer to normal]. Anything below this indicates either a shorted or partially shorted field. Also check from either one the field terminals and frame ground should be an open circuit if not then there is a short to ground. If you indeed getting 12V in and out then the grounding relay is fried or you have bad wiring or bad ground.

See schematic below.

View attachment 60658

When I pull the switch, the voltage through the PTO harness jumps up to about 14v. I get that on both wires with the multimeter grounded to the engine.
The PTO doesn't click.

 

[StarTech]

Please what I posted as it likely you have two problems

• Shorted PTO clutch windings if you indeed reading zero ohms across the windings.
• And a burn out grounding relay.
• Still can be also bad wiring cause by the shorted clutch.

 

[PTmowerMech]

Please what I posted as it likely you have two problems

• Shorted PTO clutch windings if you indeed reading zero ohms across the windings.
• And a burn out grounding relay.
• Still can be also bad wiring cause by the shorted clutch.

Thanks man, this ones for you.

 

[sgkent]

someone posted a while back that the connector on theirs rotted internally. Make sure the PTO is actually getting voltage and that the ground connection is good too.

 

[StarTech]

someone posted a while back that the connector on theirs rotted internally. Make sure the PTO is actually getting voltage and that the ground connection is good too.

Yes F56 [Packard, GM, Aptiv] terminals do break along the spring hinge causing loose connections. And many mowers uses these terminals. I just keep a good supply of them on hand here.

 

[PTmowerMech]

Ok, I'm completely lost now.

Installed the new clutch and still nothing. I pulled the flat plate out of the seat safety connection and the started working.
Here's the kicker(s)

With the seat safety switch connection plate pulled out, if the PTO is on, and I get up off the seat, the engine dies.

With the old PTO on it, I was getting 14v to the PTO with the switch on. No juice with switch off.
Was getting no ohms. (and still not getting any, after I took it off and tested it again)
Also, I connected my jumper battery to the PTO, now it's clicking like it's supposed to.
Why wouldn't the PTO come on, while it was on the mower, with juice going to it?

 

[StarTech]

You can juice going to it all day but if the juice don't flow out it will not work. But the relay circled isn't working the clutch will not work. Do this temporary. Connect the clutch and probe the connector and find which wire has 12v on it the PTO switch is on. [Just in they change the wire color code]. Now connect a long jumper to the other terminal. Reconnect the clutch. Take that long jumper and ground to the frame. This should allow the PTO clutch to operate and prove that you have a grounding issue related to the relay. It might be burned relay contacts as this disengages the PTO in reverse unless the RMC button is pushed for mow in reverse.

 

[PTmowerMech]

You can juice going to it all day but if the juice don't flow out it will not work. But the relay circled isn't working the clutch will not work. Do this temporary. Connect the clutch and probe the connector and find which wire has 12v on it the PTO switch is on. [Just in they change the wire color code]. Now connect a long jumper to the other terminal. Reconnect the clutch. Take that long jumper and ground to the frame. This should allow the PTO clutch to operate and prove that you have a grounding issue related to the relay. It might be burned relay contacts as this disengages the PTO in reverse unless the RMC button is pushed for mow in reverse.

View attachment 60773

Ok, I'll see what that does.

If the relay is bad, why does the PTO now kick on turns the blades fine (since I removed the connector plate from the seat switch)?