Electric PTO OK but not engaging

[LT46-XT1]

Edit: Solution is posted at the end of this thread.

Greetings, I am looking for some guidance with a CC lawn tractor electric PTO that won’t engage. I have documented the problem and my efforts below. At this point I suspect the reverse control module is faulty however I understand it is not a frequent failure point and it is about $200 to replace so I want to see if there are any other troubleshooting steps I should do. Unfortunately, I cannot find any information about the module and how to test it. I can’t even find a pin number or pin out description. Also, I did find wiring diagrams for similar CC lawn tractors but did not find a wiring diagram for this specific model, nor one that lists the matching wire color coding or even has the same number of connections to the module.

Lawn tractor is 2018 LT46 / XT1 EFI FAB model 13A9A1CN056
This model has a magnetic push button ignition switch combined with a reverse mow control module (2063-003BB Rev 3 10-30-15). The Cub Cadet part number is 925-06427A.

“Customer states:”

Last summer the PTO would not engage on a few occasions. It would almost always start after a few attempts and once started it never disengaged on its own. Owner suspected a flaky seat switch or PTO switch but now doubts that is the problem. Getting off the seat, going into reverse or turning off the PTO switch all would stop the blades in a normal fashion. Going into reverse without activating reverse mode also stopped the blades as expected.
This spring the PTO failed to engage at all. All other functions of the mower seem to be operating normally and battery is fully charged and in good condition.

Troubleshooting steps taken so far:

PTO clutch checked with connection to separate battery via the nearest connector. Works reliably.

PTO switch bench tested last summer and again now: Multiple switch engagements always showed continuity when switch was engaged (pulled out).

Seat switch bench tested OK. Also, engine will not start unless someone is on the seat, and it does stop as expected when operator gets off the seat.
Brake switch appears to be OK. Motor will not start and module display shows “Brake” when brake is NOT engaged and an attempt to start mower is made.

Reverse switch tested good and activated normally by putting transmission in reverse. Tested at nearest connector (under the battery).

Visual inspection of the wiring and wiring harness showed no signs of damage everywhere it was visible. No PTO relay was found.

With mower on, operator in seat and brake both on or off, there is no voltage at the PTO clutch connector (from the dash, located along the frame under the hood) when the PTO switch is activated. however, there is continuity between the connector and the PTO switch (the brown / black stripe wire) so the wiring from the PTO switch to the clutch appears to be OK.

Under the same conditions as above, there is no voltage at the PTO switch pole opposite the brown / black stripe wire. This pin on the switch has a red / black stripe wire.

Under the same conditions there is no voltage at the red / black stripe wire at the reverse mow control module. There is continuity between the Molex connector at the module and the PTO switch so I do think this is the same wire and that it is a direct connection from the module to the PTO switch. I suspect is it the positive power supply for the PTO and that it should show voltage (which would be suppling power to the PTO switch) when the safety switches are not activated.

Further Details:

PTO switch is a 3PDT used in 2PST configuration. When ON: Connects a Brown wire to a dual Green Wires (a ground) AND connects Red / Black strip wire to Brown / Black stripe wire which goes to the Positive connector to the clutch. Red/Blk has continuity to the same color wire at pin # 2 of the Molex connector at the module.

As mentioned, the combination reverse control module and ignition switch has no pin numbering so I have numbered the pins myself and identified the wire color codes as shown in the photo.

Referring to the module photo, the following pins show a connection to ground with the Molex connector, PTO clutch and battery removed. These readings provide some clues to the module functions by pin number:

3. Orange / Black stripe - ONLY when brake switch is activated (1.7 ohms) (Note: originally this post said reverse switch for Org/Blk wire but it is for brake switch).
5. Black / White stripe - ONLY when reverse switch is activated (2.7 ohms)
6. Green (1.6 ohms)
10 Orange / White strip (3.4 ohms)
12 Yellow / Black stripe (2.5 ohms). ALSO shows infinite resistance (no ground connection) when seat switch is activated.
13 Green (1.6 ohms)

I am not sure what the separate two pin connector is for. The red wire shows battery voltage but the other wire (grey) shows about 0.1 volts less). There is no continuity when the module is removed and push button switch push in. Still, I suspect its part of the ignition system and not a factor for the PTO problem.

Phew.. that’s long post. Thanks for reading. If you got this far and have any suggestions before I spend $200 for a control module please let me know.

[ironman]

I would like to try and help you but I too have searched and can find no wire schematics for any tractors using a 14 pin ignition module
Previous models called it a RMC (reverse mow control) and were 7 or 8 pin.

One thing I did notice, you said "no PTO relay was found" but I believe there may be one taped in your dash harness.

[LT46-XT1]

Thanks..
There is a relay but it seems to have nothing to do with the PTO so I said no PTO relay. At any rate the relay tested OK. I wrote further here:
https://www.reddit.com/r/lawnmowers/...9sw/?context=3
I rechecked the wiring as best I could and have run out of ideas unless I can get further documentation, so looks like a $200 part will be ordered.

[LT46-XT1]

The Cub Cadet part number is 925-06427A.
Cub Cadet website says "This part replaces:
725-06427
725-06427A
925-06427"

I found a 725-06427A for a lot less money.. do you think it would work OK?
EDIT: Sounds like its backward compatible, so its on order now. Hopefully thats the fix.

[LT46-XT1]

Posting the solution for posterity:

Apparently, Lawn Tractors with this 14 + 2 pin control module are rather rare. The new Cub Cadets I have seen use the turning key style. Perhaps it is related to the fact that this is fuel injection engine. So, if you have a similar problem but a different model, then the problem is probably more likely to be something other than the module. If you have this model then check the safety switches, and the continuity to ground from the 14 pin Molex connector (as I described above) before spending money.

For me, a replacement reverse mow control module solved the problem. Mower works perfectly now.

I used a 725-06427A that I found on eBay for less than half the price of a matching part number module.

The original 925-06427A module (2063-003BB Rev 3 10-30-15) works 100% except it will not activate the PTO cultch.

[CubDieselFan]

That is good that the part fixed it. Thank you for keeping us in the loop. If you have the extra $$$, you get a spare while you can. You never know when they will stop making them.

[LT46-XT1]

Originally Posted by CubDieselFan

...get a spare while you can. You never know when they will stop making them.

Good point but there was only the one at this low price, and this mower has already been replaced with a zero turn, so it is now for sale.

Funny thing is the replacement module includes the hour meter, and it is new.. so my mower now has zero hours! LOL

Of course I will inform the buyer and give him the old unit that shows 200 hours when powered up.

Hmm.. I just thought.. now I need a new username here also.

[CubDieselFan]

What Zero Turn did you get?

[LT46-XT1]

Cub Cadet ZT1-50