PTO question- Cub Cadet 2135

[tall.guy88]

After some initial mowing this spring my PTO stopped engaging.

Questions about the PTO-

1. It has 2 male spade clips (terminals) on it. What voltage should be applied to them to engage the PTO? 12 VDC? And is one side common/ground and the other side 12VDC?
2. Any idea what fuse size a 2135 should take? Mines got a 25A fuse in it. Im sure that is too big.
3. My PTO ohms out to 7.8 ohms across the two male spade clips (terminals). Does that mean it is bad?

Any help is appreciated. Thx fellas.

[R Bedell]

It has 2 male spade clips (terminals) on it. What voltage should be applied to them to engage the PTO? 12 VDC? And is one side common/ground and the other side 12VDC?

YUP

Any idea what fuse size a 2135 should take? Mines got a 25A fuse in it. Im sure that is too big.

Are you talking the whole system or just the PTO ??

My PTO ohms out to 7.8 ohms across the two male spade clips (terminals). Does that mean it is bad?

Can't say for sure on that one, but generally speaking, they run from 3.5 to 4.0 ohms.
AS A TEST, hook up 12VDC directly to those two terminals and see if it "pulls in".

[tall.guy88]

OK so I learned the PTO actually works. If I run wire from the postive battery terminial and one from the ground to the PTO- bap it energizes and engages the PTO.

The red wire to the PTO is wired hot 24/7. It goes directly to the positive battery terminal. So what the wiring does is it drops out the second leg (blue) I assume to ground.

But thats where I get lost. I downloaded the wiring diagram and cant figure out how this thing is supposed to work.

See attached file.


In the PTO switch terminals 6+7 connect when the PTO switch is ON.
The relay then opens brown to green when the PTO switch is ON. So the solenoid which gets about 0.9VDC from the Rev Switch goes back to the Blue wire all the way to the PRO clutch. Thats is working correctly. At the PTO cluthc I get 0.9VDC. But if I read across the red/blue wires at the PTO clutch I get 0 VDC. But red to ground 13.0VDC and blue to ground 0.9VDC.

Any idea how this is supposed to work in theory? Im missing something.

[tall.guy88]

The file didnt attach.

Heres the link


https://www.cubcadetpartsnmore.com/c...ing-schematics

Cub Cadet 2135 Series (1996-1998) Wiring Schematic

[tall.guy88]

Heres a video of the situation

https://youtu.be/60eoZ22x4kI

[R Bedell]

Since the 2135 has three different wiring diagrams depending chassis serial range, what is your Chassis Serial Number ??



BTW, the video link does not work.

[Oak]

Yes, 12vdc on the red wire if the key is in the run position.

Blue has to go back to ground, so.

If the PTO switch is on then 6 & 7 are closed on the switch. Then the ground goes to the reverse switch.

If the reverse switch is good and the tractor is not in reverse then the reverse switch relay (part # 725-1648) should close the contacts for the brown & green wire. This should be a direct path to ground and the PTO should pull in.

[tall.guy88]

That was it! The reversing switch was stuck open. I jumped it out and the circuit proved. Thank you for the input. Im in HVAC and i have never seent he common or ground broken to turn a component off.

Thank you for your input.

Originally Posted by Oak

Yes, 12vdc on the red wire if the key is in the run position.

Blue has to go back to ground, so.

If the PTO switch is on then 6 & 7 are closed on the switch. Then the ground goes to the reverse switch.

If the reverse switch is good and the tractor is not in reverse then the reverse switch relay (part # 725-1648) should close the contacts for the brown & green wire. This should be a direct path to ground and the PTO should pull in.

[tall.guy88]

PTO problem solved. Video attached.

https://youtu.be/KPMLQ4eQwA0

[Cubwheeler]

A very simple explanation of the Cub 2135 reverse safety circuit of the PTO is that:

1. When the operator is sitting in the seat with the key turned on, and the Travel Pedal is in neutral or forward, the PTO clutch will turn on because the Reverse Relay coil is energized via voltage through the Reverse Switch. This causes a normally open (NO) contact inside the relay, to close, which completes the grounded side of the circuit back to the battery negative.

2. As soon as the travel pedal goes into reverse, the voltage supply to the Reverse Switch is cut off, which causes the Reverse Relay coil to lose voltage and the Reverse Relay reverts to its normally closed (NC) position and the ground to the battery negative is cut off. Since the PTO has no path back to ground, it cannot run.

For those who would like a more in-depth answer, see below, and please correct me if I missed something. I will explain, in detail, how to troubleshoot the safety system in simple terms and how it works.

Although this explanation specifically applies to some Cub Cadet models, the basics can apply to many other manufacturer's models.

Ground Circuit including Magneto Grounding

Many problems are caused by poor grounding caused by corrosion or loose connections. It is the first circuit to check.

The Cub 2135 has a fuse in the ground circuit; check that first. Then check the tightness of the ground wire to the battery. It should be tight and free of corrosion.

Using an ohms meter, with one lead on the battery ground:

In all the tests below, Ohms readings should be close to zero, less than 1 ohm.

If there are any unusual readings, remove the switch and check the socket only. Sockets are viewed from the side where the wire enters from the harness. As an example, if you were looking for the wire entering position #4 of the PTO female socket, it would be viewed from the back side and would be on the right edge.

#8illustrated pto socket.jpg
#5ground circuit illustrated.jpg

1. Check on both sides of the fuse holder with the fuse in place. Remove
the fuse, which can have corrosion on its terminals or it can be bad even
though it "looks good". Schematic location A and B

2. Check at the ground terminal of the PTO Reverse safety switch relay.
Schematic location C

#1illustrated relay3.jpg
#7illustrated back view reverse relay female socket.jpg
#16relay model.jpg

3. Check both yellow wires attached to the Seat Safety switch. Brake pedal
UP, Key Switch turned OFF. Schematic location D and E

To check the continuity of ground of the Seat Switch, which is NC, normally closed (nobody is sitting on the seat), you could check for a 0 ohms reading between position #3 of the PTO switch socket and the M terminal of the Key Switch.

#8illustrated pto socket.jpg
#6illustrated back view key switch.jpg


With someone sitting on the seat, the ground would be lost and your reading should be OL. If you suspect problems with the seat switch, this test doesn't prove that the switch will always work, but it shows that it works this one time.

4. Check the Magneto ground wire, which connects to the Key Switch as
yellow.
5. Check the Key Switch green wire.

#6illustrated back view key switch.jpg

6. Check between terminals M and G of the Key Switch with the key OFF.
7. Check the socket female terminal #5 of the PTO switch which has a green
wire feeding it. Schematic F

#8illustrated pto socket.jpg

To check the Brake switch ground circuit with the brake UP, not engaged, you can check for continuity (0 ohms) between #3 terminal of the PTO female socket and the battery ground. Depressing the brake will show a reading of OL, showing the switch is open. These results will show that the switch is working properly.

#8illustrated pto socket.jpg

Checking the PTO switch

#15pto switch illustrated.jpg

With the switch removed from its socket and turned OFF:

Using an ohms meter, there should be a 0 ohms reading between terminals 5 and 7. There should be no continuity between terminals 3 and 4, a reading
of OL. There should be a 0 ohms reading between terminals 1 and 2.

With the switch removed from its socket and turned ON:

Using an ohms meter, there should be a 0 ohms reading between terminals 6 and 7.
There should be a 0 ohms reading between terminals 3 and 4.
There should be no continuity between terminals 1 and 2, a reading of OL.

Checking the Reverse Switch

Any time the Key Switch is turned on, and the Travel Pedal is in the Forward or Neutral position, there will be a reading of 12VDC at the white wire of the PTO Reverse Relay (Hella 4RD 931 524-02).

#1illustrated relay3.jpg
#16relay model.jpg

Place the red multimeter lead on the white wire and the black lead on the relay's green wire. If there is no voltage at the white wire:

1. The fuse on the battery red wire could be blown
2. The connection between B and R of the Key Switch could be bad.
3. The Reverse Switch could be bad.
4. The ground side of the Relay Switch may not exist due to a blown fuse on
the green (ground) wire or other broken connection.

#7illustrated back view reverse relay female socket.jpg

Use the ohms function of your multimeter and put the red lead of the meter on the relay's green wire and the black lead on the battery ground post. If the reading is not near zero ohms, there is a problem.

If the Key Switch is ON and you have power at the R terminal but none at the white wire of the relay, the Reverse switch is probably bad. If you have no power at terminal B of the Key Switch, the fuse is probably blown. If you have power at terminal B of the Key Switch and none at terminal R, the Key Switch is probably bad.

#11power to reverse switch.jpg

With the key turned on, and the Forward/Reverse pedal moves to the Reverse position, the Reverse Switch contacts will open up and there will be no voltage at the white wire of the relay. The PTO will shut off because it has no path back to ground.

#15relay closed.jpg
#18relay open.jpg

If the Key Switch is ON, and you move the Travel Pedal to reverse, you should be able to hear the relay click.

The PTO safety circuit, Relay and Reverse Switch action

This riding mower is designed to shut off the PTO driving the mower deck blades when the foot pedal goes into reverse. I'm going to explain this as battery power flowing from positive to negative, as there are two views.

There is 12VDC supplied to the PTO and Reverse Switch any time the Key Switch is in the Run position. The power is supplied through the red wire, terminal R, of the Key Switch. On this particular Cub model, there may be a short extension of the harness wiring near the PTO clutch. The red wire may be extended as a blue wire and the blue wire may be extended as a red wire.
If you unplug the PTO connector, check for, and expect, 12VDC at the female terminal coming through the main wiring harness red wire, possibly extended a few inches by a blue wire. You should also measure 12VDC on the blue wire at the PTO switch female plug at position #6.

#8illustrated pto socket.jpg

This will show that the coil winding of the PTO clutch is intact, but only an ohms test will confirm a good winding. The reading through the coil is about 7 ohms.

On this Cub model, 12VDC will be measured at the PTO switch female plug at position #6. When the PTO switch is turned ON, the return circuit to the battery ground will continue through the brown wires at terminal #7 to the Reverse Relay coil, and then through a switched contact to the green wire and then back to the battery ground. Any time the Key Switch is ON and the Travel Pedal is neutral or forward, the contact will be switched and there will be continuity from brown to green.

#15relay closed.jpg

A quick test of the Reverse Relay and Reverse Switch

A functioning Reverse Relay will be energized as soon as the Key Switch is turned to Run and the Travel Pedal is in the Neutral or Forward position. Moving the pedal from Forward to Reverse will cause the relay to click as the contact inside opens up. Each time the pedal is moved, there should be a click. This test will show that the Reverse Relay and Reverse Switch are good.

You can also remove the relay and test with a battery. Apply 12VDC to terminal F and the ground to terminal H. You will hear the contact click. Using an Ohms meter, you should have zero ohms between terminals D and E.

#1illustrated relay3.jpg

The Reverse Relay

An explanation of the role of the Reverse Relay when the PTO is turned on is that after the power has gone through a resistance, which is the PTO clutch, it is less positive and behaves as the negative (ground) side of the circuit.

#10illustrated small coil pic.jpg

This acts as a negative (-) to one side of the relay coil through the brown wire. Meanwhile, a positive 12VDC is going to the Reverse Switch, which is normally closed (NC), and on to the positive (+) side of the relay coil. Since there is a positive and a negative force, the coil is energized. Once the coil is energized, the electrical path will be completed through the relay's contacts and the PTO clutch circuit will be complete back to the battery ground and it will turn ON.

The purpose of the Reverse Relay is twofold. It creates a path to the battery ground from the PTO clutch which causes it to engage AND it breaks the path to the battery ground from the PTO clutch which causes it to disengage, all depending upon the position of the travel pedal.