Throttle action becomes inoperable

[DStoen]

Hello, I have owned this LS XU5055 for ten years now and have had this same problem since it was new. After a few minutes of using the brush mower on the tractor the throttle returns to an idle and the hand throttle becomes unusable. I can continue using the foot throttle but it only lasts a few more minutes before it too becomes unusable. It will remain idling but that is all. Once it sits and cools for a time it will return to normal operations for a few minutes again. It also happens in the winter when I am pushing snow so it isn't due to heat. I sure could use some advice on how to correct this problem! I contacted the dealer when it first started but obviously he did nothing to correct it.

 

[CloverKnollFarms]

You've dealt with that for 10 YEARS?

 

[DStoen]

You've dealt with that for 10 YEARS?

It is erratic, with it sometimes going hours and other times only minutes before it reduces the throttle to an idle. I sure miss the mechanical linkage of the older tractors.

 

[alexpops]

Looking at the schematics & wiring diagram, I'd check the connections to the feed pump (24 in the second image).

Welcome!! LSMtron Web Parts Catalog

 

[GS650GL]

Normally there should be fault codes displayed on the dash when this happens. Check all the grounds and wire connectors. It is possible the hand or foot throttle sensor is defective, but sometimes a bad crank sensor can affect the throttle because they share the same 5 volt power supply from the ECU. A dealer with the laptop service tool can monitor the function of the hand and foot throttle and can also see a screenshot of engine parameters in the stored data log when the fault occurred. They can also see fault code history even if no codes are active now.

 

[CloverKnollFarms]

It is erratic, with it sometimes going hours and other times only minutes before it reduces the throttle to an idle. I sure miss the mechanical linkage of the older tractors.

Mine is a 2023 and it's still mechanical. But not an LS

 

[alexpops]

Something else to check is the main battery ground to frame & the connections for the main fuse off the positive post. I had all kinds of wonky electrical issues until I replaced both cables/posts/and the main fuse set-up.

 

[Avenger]

There should be an error code. Every time the tractor throttles itself down, it does it for a reason. Well, the tractor thinks it does it for a reason, if that reason is warranted or not. The point is, every time the tractor does something the operator does not expect, the tractor tells the operator what it is. They can only 'speak' to us in code: error codes.

Your tractor is going into limp mode for a reason. You might be correct with the cooling cycle. Check to make sure your radiator is completely clean and you have a full radiator. Also, check the coolant for protection. Too much straight antifreeze is not good. 50/50 mix.

The next thing to check is your chassis ground. As others have mentioned, a bad ground has been the cause of many issues with these tractors. Take it off, use a grinder and remove the paint, use dialectic grease (or even vasoline) to coat the connection, and use a new bolt to attach the ground back to the bare metal.

If the problem continues, check the sensors. The only real way I know to do this is with a dealers help. You'll need one of their laptops.

10 years is a long time to go with this issue. Intermittent or not. If my tractor ever throttled down without me telling it to, it would be a major issue for me. It has (knock on wood) only ever happened once for me. It flashed a code as the tractor throttled down and shut off. My treated diesel was gelling up on me in the extreme cold.

 

[DStoen]

Normally there should be fault codes displayed on the dash when this happens. Check all the grounds and wire connectors. It is possible the hand or foot throttle sensor is defective, but sometimes a bad crank sensor can affect the throttle because they share the same 5 volt power supply from the ECU. A dealer with the laptop service tool can monitor the function of the hand and foot throttle and can also see a screenshot of engine parameters in the stored data log when the fault occurred. They can also see fault code history even if no codes are active now.

Hello again, I am still attempting to figure out why the XU5055 goes into limp mode so often. I was off the chase for a while as I had some leg surgury and can't walk for another 4 weeks. I was able to run the tractor without it going into limp mode for about 2hrs after I changed the fuel filters and the tank fuel on the tractor. Then I was on my way home from getting new tires installed and it started the same old crap. I made it home and decided to again change the fuel filters and remove the fuel tank and check the fuel lines for any blockages. None noted. I replaced the tank and filled it with fresh fuel from a busy diesel station. Once started it ran without incident again for about 45 minutes. Then while useing the hand throttle it started to buck and acted like before. I pushed the hand throttle up and utilized the foot throttle and all the issues appeared to disapear. Now the only time it will quickly go into limp mode is if I attempt to use the hand throttle. How can I diagnose that the operation of the hand throttle components are responsible without replacing more parts only to be wrong again?

 

[GS650GL]

You never mention if there are any fault codes. As stated previously, the only way to accurately diagnose is with the dealer's service tool laptop computer. If it only does it when using the hand throttle and not the foot throttle, I think you answered your own question.