I'm about to start working on a 1984 model year JLG 60G. I can get the machine to operate everything like it should from the back of the machine, but from the platform, The machine will go in reverse not forward, can get the boom to go up but not down, can get the platform to rotate one direction but not the other, and the platform tilt will operate up but not tilt down. I'm leaning towards an electrical issue, but I really don't know where to start troubleshooting. Can anybody give me some advice? Thank you!
Let's start with basket voltage. Do you have at least 12 Volts available in the basket with the engine running? I'm imagining you have PQ controllers, that's all I've ever seen used on a G series. These controllers have a micro-switch that turns on power to the controller whenever the controller is moved from the center position. Make sure you have power to the micro switch and away from the micro switch in both handle movement directions.
Next, locate the two wires on each controller that are attached to the coils on the proportional valves. These are typically a solid and a stripe. For example, one will be orange, the other white with an orange stripe. I don't have a 60G print, so I can't give you actual terminal numbers. Locate the right wires, follow them to the terminal block inside the basket control box. With your voltmeter ACROSS these two terminals in the basket junction blocks - you should read nothing until a controller is moved from center. Off center, you should be reading approx. 6 volts. Stroking the controller one direction, will cause the voltage to rise towards 12 volts. Stroking the other direction will cause the voltage reading to drop towards zero. This will confirm whether your controllers are functioning properly.
Thank you for your replies, OFF! I do have an update since the issue occured. When we had trouble with the machine, it was about 100 degrees outside, and was operated(driven) about 3/4 mile towards the jobsite. The next morning, when everything was cooled off, there were no issues whatsoever. When we get the machine hauled back to the shop, I will follow what you have suggested I do. If nothing else, I'm gonna learn something new, and to me, thats what its all about. I'll keep you posted on what I find. Thank you!!
over heated hydraulics will do all sorts of funny things. What a perfect storm of symptoms! Some machines had a hydraulic rad and cooling fan, others didn't.