JLG60H Engine stops when Foot Switch is pressed

[01RAMer]

You are exactly right.

The manuals I have are dated 1988 (3120629 & 312030). The P-Q Controls Supplement is updated to June 1994. My foot switch schematic is on the Power Distribution Wiring Schematic for Ford with Solenoid Operated Throttle which is what this was before it was upgraded to the EE301 Precision Governor. It appears we are on the same page which is wonderful!

I believe the terminal block was corroded beyond repair so the previous owner connected wires together with 3M connectors, which I am not a fan of, so I reconnected the wires together, soldered them for good contact and heat shrink them. (Only on the platform). Unfortunately that didn't resolve my problem which I had hoped it might.

I have already changed out the relay and am in the process of changing out the diode which is a 600v 6A. I tested it when I had it apart and it tested good, but it might be breaking down during use, so we'll see if that makes a difference.

I don't see any capacitor on my drawing nor do I remember one in the panel, but I think I see a cap on the full size 1991 drawing I have with a number 34 pointing at it and another strange thing at the Aux Power with the numbers 31,32 & 33. Are either of these what your talking about? I'll double check that panel tomorrow but I don't recall seeing any components in there.

 

[01RAMer]

Update

Rain let up for a while yesterday so I checked for a capacitor and there isn't one. I already replaced the foreign relay, and changed out the diode yesterday. Nothing changed to correct my issue.

I decided to recheck the wiring at the basket, the voltages and recheck the cable to the foot switch and the foot switch itself. With the engine off (so I could see voltage drop better) I checked the voltage at the Emergency Shutoff and I only had 10.17 volts. I disconnected the cable going to the foot switch and rechecked and got a good 12.4v. I reconnected the cable to the foot switch and took the top off the foot switch. I disconnected the black common and got 12.4v at the wire. Reconnecting that, I pulled off the Orange wire, that changes to blue and goes back to the main panel, and I got 11.4v coming in. I disconnected the white wire that goes to the new relay and got my 12.4v back. That makes sense due to the voltage drop caused by energizing the relay. Reconnecting everything back up, I get the 10.17 and when I press the switch, the voltage plummets to 4.9v. Just a note, with the engine running and the orange disconnected, I get 13+ volts everywhere.

With the testing finished on the basket I feel the basket is fine, so my next stop is the blue wire coming into the main panel. I can't figure out where that blue wire all goes to on the schematic, so I'll have to trace it to where ever it leads.

If you have any insights as to where the blue wire goes once it gets to the main panel, I would appreciate it.

 

[OFF]

According to the 60H drawings I have (good for serial #70237942 thru 70237949) the blue wire is left swing. You said the wire was orange before it turned blue? Orange is the starter button. Someone may have had a problem with the start wire and switched the two. You're going to have to see where that blue wire goes after it enters the main panel.

 

[01RAMer]

According to the 60H drawings I have (good for serial #70237942 thru 70237949) the blue wire is left swing. You said the wire was orange before it turned blue? Orange is the starter button. Someone may have had a problem with the start wire and switched the two. You're going to have to see where that blue wire goes after it enters the main panel.

On the schematic I sent you, by the foot switch wiring, it looks like the orange wire connects to the blue wire at #2 terminal, but then I have so many different schematics it's not funny. Serial numbers are confusing to me also as the ones you listed above only have 8 digits, while my serial is 0308509394. I assume this indicates mine machine is newer than your schematics. Oh well, I'll find out where it goes. Can you tell me if the power is suppose to be going to the main panel from the foot switch or coming from the main panel?

One more thing, do you know what a Bang-Bang Dump Relay is? I think the one schematic is showing the Horn switch going to a Proportional Dump Relay, then to a Bang-Bang Dump Relay and to a Engine Shutdown Relay, which takes you back through the Platform/Ground select switch to that blue wire coming from the basket. I'm getting too old for this. Thanks!

 

[John Henry 1951]

Hello everyone. New to the forum and I find it most informative. I have a 1992 JLG 40H with the Ford LSG 423 gas engine. I am also having problems with it not starting from the basket I can start from the ground, switch to platform and it will keep running but when the foot petal is depressed it kills the engine. I have a service manual but as many have pointed out it is almost impossible to read. The wiring under the console is a rats nest. Is the capacitor connected to the right terminals? It has an arow on it. is power flowing the right way? Is there anyone out there that has the same lift and could take a picture of the terminal block under the console? That would be a huge help. Thanks for reading.

 

[MtnMann]

I have a 1988 60h with the Ford LSG. I can take a pic under the platform panel tomorrow if that helps. You referenced a pic but I don't see any pic posted...

 

[OFF]

Hello everyone. New to the forum and I find it most informative. I have a 1992 JLG 40H with the Ford LSG 423 gas engine. I am also having problems with it not starting from the basket I can start from the ground, switch to platform and it will keep running but when the foot petal is depressed it kills the engine. I have a service manual but as many have pointed out it is almost impossible to read. The wiring under the console is a rats nest. Is the capacitor connected to the right terminals? It has an arow on it. is power flowing the right way? Is there anyone out there that has the same lift and could take a picture of the terminal block under the console? That would be a huge help. Thanks for reading.

I know I am late to the party, but are you still fighting this battle?
Normally when stepping on the pedal kills the engine on an older JLG product, it's a voltage drop situation. Do you have a volt meter? Test from the ignition switch in the basket to a good ground. You should be maintaining something over 12 volts with the engine running. If the voltage drops to zero or even below 9 volts when you step on the pedal, the engine will die.