I just unloaded my 2004 PC78 and it will not throttle up. The guy who sold it to me said it just started doing that when he went to load it. He had used it a couple days earlier and it worked fine. He has been a standup guy and I do not doubt him. He said it blew the fuse for the motor that adjusts the throttle, he thought it had some water in the line that might have froze as it sat outside. I see on the monitor in front of the right hand controls that it shows an icon that looks like a slow speed picture. Not the two speed travel icon, and different one. I see there is a similar (if not the same) picture on the button on top of the left hand joystick. This button does not do anything and feels like it might need to be replaced. Am I on the right track here or is there something else that I should look at? Thanks!
Jake, Stupid suggestion, maybe, but try it anyway... Do you have the auto-idle button pushed in on top of the l/s joystick? If so, this will prevent the engine from revving up. A bad switch can cause the same thing. I work for a Komatsu dealer and have seen this happen before. Try starting the machine and clicking the thumb switch on top of the joystick (same tyoe of switch as the horn switch) and see if that works. I'd be curious to see how you make out. Regards, Tony
Problem was in the low idle button on the left joystick. The rubber handle needs some adjusting as it was not allowing enough give in the rubber to actuate the switch. I took it apart and the switch is in great shape.