Hey there. New to the site and need help from smarter minds. I have a jlg 40h that has blown the main fuse. 35 amp. If the machine is shut off the fuse can be reset but as soon as I turn the key on in ground or platform control it blows again. The only other contributing problem could be the loss of high gear a couple days prior but that seemed to be a faulty toggle for high engine. Any ideas where to start? The goal is to get it running and loaded to bring it in for service. Mobile mechanics while very good are very expensive. Thanks
Welcome to HEF siderman. :drinkup What engine does your 40H have?
Deutz diesel.not sure what model. I will be on site tomorrow and can check.
It should be the F3L1011 Deutz engine. If it trips the main 35 amp breaker immediately, you have a dead electrical short to ground. Ordinarily this wouldn't be too hard to find, but the problem is there is a number of circuits that can cause this. If you're going to a job site to troubleshoot this you definitely need the wiring diagrams with you. If you don't have them, you can download at the JLG website, both service and parts manuals. The parts manual has cleaner diagrams than the service manual. If you've never worked with JLG diagrams, I suggest you start looking at them and learning before you go out there because their diagrams can be complex to read. With all that out of the way, since it trips the breaker whether in ground or platform positions, we know it's not a problem with boom cable or platform controls so don't focus there, do your troubleshooting with selector switch on "ground controls". The first thing I'd do is disconnect the fuel run solenoid at the engine, this is a very likely cause of your problem. If it no longer trips the breaker with fuel solenoid disconnected, problem solved. But if it continues to trip breaker, life just got way more complicated. I doubt the short is in the yellow wire circuit at ignition switch as it's protected (at least should be) by a 10 amp CB. If the problem were in that circuit it should trip that 10 amp CB before it trips the 35 amp main CB. This seems to indicate the short is in the main power distribution on terminals 12 through 16 on main terminal strip. Disconnect the yellow 12 gauge wires from terminal 30 on relays R18 and R19, turn on ignition, I'm hoping at this point it no longer trips breaker. If it doesn't, leave ignition on, and touch either of the two yellow wires you disconnected back on their respective relay terminal. If breaker now trips, you know the short is in the main power circuit distributed by terminals 12 - 16 at the terminal strip. Remove the jumper strip secured to these terminals so 12 - 16 is no longer jumped together, this will make terminals 12 - 16 individual circuits. Reset breaker, turn on ignition, then connect a jumper test lead to terminal 30 of either R18 or R19 (the terminals you plucked the yellow wires from). With opposite end of test lead, touch terminal 12 of terminal strip, then touch 13, then 14, do this until you find the terminal circuit that trips the breaker giving you a path of which you should follow. This is about as far as I can walk you without more information. Hopefully you'll find your problem tomorrow.
Wow. I definitely came to the right place. Thanks. I will spend the day with the schematics and follow your advice tomorrow. I will let you know.
So I tried it today. Still blew breaker when I got there so I disconnected one wire from the fuel solenoid( I think) and it started right up. I reconnected to verify that was the cause and it continued to run.(don't really understand that) but it is loaded now and I can get it in to Levitt for repairs. Thanks for your help and knowledge.:notworthy