1997 JLG 600S Fast/Slow Drive Speed

[PMMC2012]

Hello all,

New to the boards here, but I see that there are a lot of helpful members out there so here is my particular dilema.......

I have a 600S that will idle the diesel motor up to go into fast drive speed (not for the boom, but for the drive gears) but will not engage. I had a tech come out and he said there is a solenoid that monitors the basket's weight load which is a "fail safe" measure and that it may have gone bad. He explained it as such if the lift thinks that the basket is overloaded, it wont engage the fast forward speed. Does anyone know if this is correct or where this sensor or solenoid is? Any help is appreciated!

Thanks,

Shawn

 

[barklee]

Hello all,

New to the boards here, but I see that there are a lot of helpful members out there so here is my particular dilema.......

I have a 600S that will idle the diesel motor up to go into fast drive speed (not for the boom, but for the drive gears) but will not engage. I had a tech come out and he said there is a solenoid that monitors the basket's weight load which is a "fail safe" measure and that it may have gone bad. He explained it as such if the lift thinks that the basket is overloaded, it wont engage the fast forward speed. Does anyone know if this is correct or where this sensor or solenoid is? Any help is appreciated!

Thanks,

Shawn

I have a 2004 600s with this problem. Does yours go in slowest creep mode? Mine turned out to be the roller switch on the bottom of the boom lift cylinder. That is what tells the machine the boom is low enough to engage fast drive speed. My will stick in the raised position once in a while and you have to crawl under the counter weight in the rear and look up and you will see the bottom of the boom lift cylinder. There is a little sheet metal shroud off to the side and behind that is two roller switches. I believe the top one is the culprit. You dont have to remove anything to access this, but you might need a flashlight to see it. That is just an option to try...... Beyond that it could get pretty technical.

 

[PMMC2012]

I have a 2004 600s with this problem. Does yours go in slowest creep mode? Mine turned out to be the roller switch on the bottom of the boom lift cylinder. That is what tells the machine the boom is low enough to engage fast drive speed. My will stick in the raised position once in a while and you have to crawl under the counter weight in the rear and look up and you will see the bottom of the boom lift cylinder. There is a little sheet metal shroud off to the side and behind that is two roller switches. I believe the top one is the culprit. You dont have to remove anything to access this, but you might need a flashlight to see it. That is just an option to try...... Beyond that it could get pretty technical.

Yes, It will run in slow mode without any issues. It used to run in fast mode most times, but and it did have an intermittent problem if the boom was either too high or too low to engage fast mode. It's possible that it could be one of the roller switches. I have the service manual for it so I will try and run it down.

Thanks for weighing in Barklee, and if anyone else has any other input or experience with these type of JLG lifts please feel free to chime in! :waving:waving