rookieatbest
Active Member
98 JLG 40e Problem
thanks for the recommendation, will call the start of the weekI don't thing those units used a creep mode on the drive motors, the drive joystick control simply sends input to the MOS90 motor controller for fwd/rev direction and proportional speed input. The MOS90 does everything from there. Have you checked the LED on the MOS90 to see if it's flashing any fault codes? Aside from that, if you suspect a problem with the MOS90, call Hindley Electronics and see if they can test the unit, or if they can't if they can recommend someone who can test it. It's been years since I've worked on one of those, but I do recall sending one off once to have it tested, just can't recall who I sent it to. Be sure and check all your contactors, look for evidence of one with burnt contacts or even one stuck.
I purchased a 1996 JLG 40E a few months ago. All functions seemed to work fine, all lift functions, rotation, etc. but the drive system was very slow and lethargic no matter how the potentiometer was set. When I checked the batteries that the previous owner had in place, they were a hodgepodge of different sizes with only 3 of the correct batteries, so I purchased a complete set of new, correct batteries. The drive was still lethargic and now the lower boom tries to lift but does not rise more than an inch no matter what the potentiometer is set at. Frustrated I left it alone for a week, when I went back to it now the lower boom works fine for a while, then while I was trying to use the unit, now the lower boom won't lift anymore and has not since. Yes, the drive is still lethargic and I actually had to tow the unit with my tractor at one point to get it to move. I tested the motor controller and the voltage from the #4 pin and B- is over 50 volts, both static and under drive. I jacked up the drive wheels and they both move in both forward and reverse, but had no real power. Are these two issues, failure of the lower boom to lift and lethargic drive connected? All other functions work fine. Can anyone help me figure this one out. Thanks in advance!