guys I hope you can help a desperate soul. I have a issue with the upper lift control on the 450a 1999 model jlg. everything seems to work from the platform except lift up on the joystick. I have not tried the speed control but all the other switches work. The lift function works fine on the ground panel and the lift down and swing left and right work fine, just no lift up. I can lift from the ground control and then climb in the bucket and move joystick down and the platform will level out and lower like it should. I switched out cards with swing control and it still has the same issue. I traced out 3-1 and 4-1 with schematic ( which is really tough for me to follow ). 3-1 is a brown wire and I believe ends up at ground panel connection number 6. I dont understand where is goes from there. right under the number 4 slot is the ground panel lift wiring 3-3 and a 3-2 ( I dont see 3-2 on the schematic anywhere) it goes in the lower slot 4. where do 3-1 and 3-3 connect together or how do they connect together or do they not combine and then go to the lift valve? thanks
3-1 is a Tan wire that runs from the Upper Lift Up/Down control card to Terminal 6 in the Ground Control Box. 4-1 is an Orange wire that runs from the Upper Lift Up/Down control card to Terminal 4 in the Ground Control Box. 3-2 is a Tan wire that runs from the Lower Control Box Upper Lift Up Switch. 4-2 is a Tan wire that runs from the Lower Control Box Upper Lift Down Switch. The fact that it works well from the Ground Controls, the assumption is that wires 3-2 and 3-3 are wired correctly. That would indicate that the issue would be with the 3-1 wire. 4-1 wire appears to be in working order so it is undoubtedly ok. A real fast test of the 3-1 wire would be to swap the Orange 4-1 wire and the Tan 3-1 wire. Put 4-1 where 3-1 is and the 3-1 wire where the 4-1 wire was. If the boom now goes up but not down from the upper control box then it is obvious that there is a break in the 3-1 circuit between the Upper Lift Up/Down Control Card and Terminal 6 in the Ground Control Box.
3-1. 3-2, and 3-3 join together at terminal 6.
ok went out today and per Mr. V's instructions swapped wires and the Lift Up function did work. Traced out 4-1 and it went to where it looks like a relay should be. 4-1 then turns into 4-4 and then runs to the ground control panel. I jumpered over the area slot for the relay and lift up and lift down work now. Thanks for the help on that. What relay is suppose to go in this pic. I dont see it in the schematic and do you remember what it is for. lift function is working without it so I am happy but just like to know what its for. one last question and I will leave you alone for awhile.. Ha Ha what is this valve for? Valve is located behind the ground panel box and runs behind the hydraulic tank and I believe it is attached to LL on the valve box
If the other end of the valve heads to the Lower Lift Cylinder, then it is the Lower Lift Cylinder descent adjustment: Where did the relay that was in the socket go to? It is for a lift cut-out circuit. Follow terminal 14 of the relay block (black wire) back to a proximity switch to verify the switch is working. Find the relay and re-install:
the relay was not there when I got the machine. I am going to buy one and install it and go from there. I cant get my head around how this lift down was working without that relay because 4-1 to 4-4 has no way to connect without a relay. I guessing during troubleshooting I swapped orange and brown in the ground panel and dont remember doing it. I was tracing out the 3-1 because up was not working and the whole time whoever had the machine had swapped the wires in the ground panel. I will post the results when I get the part. thank you for the help. Maybe these threads can help someone who also has similar problems with there lift.