LA140 Mower Engagement problem

[Etch]

I have a 2006 LA140. I have had no problems with the lawn tractor since I've had it and I really work it hard consiering it has to mow over 2 acres every week through thick bermuda grass on a pretty bumpy yard.

Last week I encountered my first problem. My wife was mowing and she said it started dying on her and would eventually stall. after a couple stalls it wouldn't start. We had a lot of rain recently and the lawn was pretty thick, so I thought maybe it was overheating. I let coold down and started it right up, but then it started to stall. I choked it up to full and ran fine for another 10 seconds and then died. We cleaned the gas tank vent hose and all was fine until about 30 minutes of mowing. The blades stop turning, but the mower ran fine.

Today I replaced the battery since it had a difficult time turning over the motor. Tractor starts fine now, but will not engage the mower. Then I noticed that if I hit the Rio button and go in reverse, the mower would engage, but as soon as I let off the reverse pedal it would disengage. I cleaned all the contacts on the brake switch, rio switch, seat switch, PTO switch, and relay connector. No change. No wires are frayed.

I then started looking at the seat switch. If I'm sitting on the seat and engage the PTO, the mower won't attempt to engage. If I get off the seat and engage the PTO, the blades try to engage and the mower stalls, like it would normally if you were to get off the seat with the blades engage. I bypassed the seat switch with two wires on the harness, and it did the same thing.. tried to engage and then stall.

Could it be the relay?

 

[Etch]

echo echo echo

 

[jinman]

We're all scratchin' our heads right along with you.

 

[Etch]

I'm going to try replacing the RIO switch. It's $7, easy to replace, and seems to be the leading suspect.

 

[jinman]

I'm going to try replacing the RIO switch. It's $7, easy to replace, and seems to be the leading suspect.

Why not bypass it? I pulled the plug going to mine and put a simple jumper with two spade connectors into the plug. My wife loves not having to punch the button to mow in reverse now. BTW: You do have an electric clutch PTO for your deck don't you? Don't you pull a switch on the dash to start the blades? I'd start there and work my way down to the electric clutch. Too bad you don't have a schematic.

 

[Etch]

I did pull the plug and bypassed it, but it didn't make any difference. I read somewhere during my search that bypassing might not actually work. Something about resistance built into the switch or something. I tried bypassing the seat switch and then pulled out the PTO switch and ran bypasses there as well. I even tried bypassed the brake switch. I tried everything..lol

BTW what year is your lawn tractor?

 

[jinman]

BTW what year is your lawn tractor?

My JD is a LA145, purchased in April of '08. I purchased it from the JD dealer, but it is identical to the ones sold at the box stores. On mine, anytime you pull the PTO switch, the clutch engages. If you get out of the seat, the engine dies, but the clutch stays engaged. (I'm pretty sure, not 100%) I do know that before I bypassed the RIO switch, if I started to mow in reverse, it would mow, even though the engine was dying, until the engine rpm came to a halt.

Earlier, you mentioned a relay. I haven't researched this, but I was not aware there were any relays on the mower. I thought everything was done with switch logic. I haven't had any electrical problems, so I've had no reason to do detailed electrical troubleshooting. I wish I knew more and could help, but about all I can do is tell you how mine works. If there is something you would like for me to check as a comparison, let me know. I'm old and slow, but I'll give it a go.

 

[jinman]

Hey Bill, this is not a schematic, but it may help. I've downloaded the wiring harness and parts diagrams for your LA140. They are attached below. There is one relay (Item 25 first illus - not sure of its function) that is a simple SPDT that is no more complex than a switch. My guess is that it is a high current relay controlled by a low current switch. . . not sure.

 

[Etch]

Wow! Thanks for the diagrams. They help alot. Number 25 is exactly what I was referring to and I can not figure out what that does either. I'm going to check a few other things today while I wait for the RIO switch to arrive. This shouldn't be so complicated, but I have yet to figure out what is wrong. Meanwhile, I'm mowing my back yard with my Mahindra and my front with a push mower. That needs to stop!

 

[jinman]

Well, now I'm confused. I saw the LA140 in your title and posted those diagrams. Now, I see your signature says "2007 LA145," so I'm concerned that I sent you the wrong thing. My LA145 is very close, but might be a tiny bit different.

 

[Etch]

No, it was I that was confused. It is an LA140. I'll have to correct my signature.

The good news is, I fixed the problem. It was the connector on the PTO Clutch. One of the black wires had broken off. I had looked at it before, but had never touched it. This time I touched it felt that the wire wasn't connected.

Thanks again for the diagrams!!

 

[jinman]

Bill, glad you found it, that's terrific. While you are checking the the PTO clutch, walk around to the left front side of the mower and look at the flat metal "strap" that holds the clutch secure. Just a few months ago, my strap broke and my clutch spun, ripping the wires apart. The strap is cheap and it has a plastic grommet inside the clutch for some padding, but everytime you bottom out the blades or hit a rock or other obstruction, the clutch delivers a blow to this strap. It's not very beefy, so it can easily break. Just keep an eye on it. The strap from JD is less than $4, so it's cheap insurance to replace it about every 4 years or so.:thumbsup:

EDIT: BTW, I'm adding this broken wire and the way it reacted to my "bag-o-tricks" for future reference.

 

[FHH]

My problem sounds similar but somewhat different now. I have a John Deere LA140 that is about four years old. I have recently had issues with the mower engaging then disengaging. After reading other forums, I determined it could be the battery (which was old) so I replaced that and the voltage regulator. After testing everything, that is not a problem. I'm getting proper voltage and the stator is putting out more than ample charge to keep everything going. I also had the issue with the wire breaking off the connector at the PTO clutch under the mower. At first I just crimped it back on but after the mower quit engaging at all I just purchased an all new wiring harness (included the new connector for the PTO clutch) and installed it. Still no dice. When I try to engage the electric PTO it makes no noise at all, no attempt to start the blades. It doesn't matter if I get off the seat or not, the blades do not attempt to engage. I tried to test the continuity of the PTO switch (new to me since I'm an accountant by trade) and I got tones when I touched opposite poles. Don't know if that makes it all okay with the swtich but it sounds okay. Does anyone else have a clue as to what this could be? In parts I've spent about $180 at this point. The service call to the local JD dealer will be $139 plus parts so I'm motivated to do this myself but can't keep guessing and spending. Thoughts? Thanks for your help!

 

[coveylane]

I wish I would have found this earlier. I searched and searched for a cause for my PTO not to engage and today I found one of the black wires was broken off inside the insulation like yours. I found those wires are too short for the change in direction under there by the clutch and puts quite a strain on them.