JLG 45HA - Problem with upper controls

[knares]

the wires 5 and 6 from any of the PQ controls have only about 3 volts, No7 has 0
at the same time No3 still has 12v

 

[willie59]

You won't see 12V on 5 and 6. Those two terminals are the function outputs of the controller. The output on those terminals is Pulse Width Modulation, or square wave, it happens so fast you can't see 12V checking it with a meter.

Terminal 7 of the controllers, if it's used, is a 12V input from an external/separate source. In the case with this machine, it would be a wire from the creep (snail) switch. When you flip the creep switch it sends 12V to terminal 7 of the controllers, this input reduces the control output of the controllers (creep mode) for nice slow operations when you have the basket close to things.

 

[knares]

The output on those terminals is Pulse Width Modulation, or square wave, it happens so fast you can't see 12V checking it with a meter.
O’ the plot thickens
If i am understanding the wiring diagram correctly, relay Ri, terminals No9 and 10 are common to both basket and ground controls for the Main Lift.
Bearing in mind what you said about not getting a proper reading,
As i only have a volt meter
In basket mode the terminals read about 3 volts and two of them try to work
In ground control mode they read about 6.5 volts and everything works

 

[willie59]

If you're new to reading JLG diagrams of this vintage I can assure you it's a learning experience. And I've even found errors on JLG diagrams, don't recall if there's any on the 45HA diagrams though.

JLG refers to R1, R2, and R3 relays as "Select" relays. They're used to select upper or lower controls for the main boom functions and opposite of that they "lock out" the control station that is not selected. In other words, when you select "ground" controls, R1 R2 and R3 connects the switches in the lower controls for main boom functions to their respective valves, at the same time they "disconnect" the upper control switches or controllers from said function valves. They prevent main boom functions from being operated from both platform and ground controls at the same time.

R1 controls main boom up/dwn and tower boom up/dwn.
R2 controls tower telescope in/out and boom swing left/right
R3 controls the dump valve for proportional valves and the dump valve (block valve) for the bang valve functions.

Platform level, platform rotate, and platform steer are not routed through the select relays R1 R2 R3, neither is the drive controller as it only has a control for drive at the platform.

I don't know what voltage one would see on the outputs of the PQ controllers, like I said, can't really test PWM with a volt meter. One could test outputs by measuring milliamps, but you'd have to know the desired value in milliamps, and it would require a jumper harness to connect the meter without cutting wires to tap the amp tester in the circuit.

As for the outputs at ground controls, the functions that are proportional controls at the platform, i.e., boom lift, tower lift, and boom swing, operate at a reduced voltage output via a resistor that feeds power to those toggles in the ground control box, you won't see a full 12V output at the lower controls for those respective functions because of that resistor. Other functions, platform rotate, platform tilt, etc, you would see nominal 12V output on the switches.

 

[knares]

hi, thanks willie, can you Identify these relays for me(R?),
If i disconnected the PQ from the harness and ran a wire from pin NO3 (12v positive) to pin No5 or 6, do you think it would do any damage (hot wire it)(give it a full 12v)

 

[willie59]

If that's the upper control box I have no idea what all those relays are doing, never seen that before on a 45HA and I don't see them on any diagrams.

I've never put a full 12V on the output wires that are connected to a PQ controller, pin 5 & 6, so I don't know what would happen. The result would most likely be movement so fast it would be uncontrollable, even the lower controls for proportional functions (boom, swing, etc) don't apply a full 12 volts with the toggles because the power is routed through a resistor to reduce the voltage going to the proportional control valves controlled by toggle switches.

 

[knares]

I haven’t tried a full hot wiring it, because my thoughts were the same as yours

 

[knares]

Those relays are in the parts book at the agents

 

[willie59]

If that's the upper control box, and you see those relays in some form of parts book, then I can only conclude there is a difference in North America machines and versions built for OZ because I don't see any relays in the upper box.

 

[knares]

well I have been busy doing other things and we have had to manage without it but i am going to have to have another go at it as it wont fix its self

 

[Charles Whiddon]

You won't see 12V on 5 and 6. Those two terminals are the function outputs of the controller. The output on those terminals is Pulse Width Modulation, or square wave, it happens so fast you can't see 12V checking it with a meter.

Terminal 7 of the controllers, if it's used, is a 12V input from an external/separate source. In the case with this machine, it would be a wire from the creep (snail) switch. When you flip the creep switch it sends 12V to terminal 7 of the controllers, this input reduces the control output of the controllers (creep mode) for nice slow operations when you have the basket close to things.

Willie I have a JLG 45 HA when in creep mode the main boom will not lower I have to put it in rabbit to lower the main boom the boom will raise in creep mode. I changed all the PQ controllers and adjusted them as per information found on this forum. Can you give me an idea of what to look for? I tried to start a conversation with you but I guess I haven't figured out how to do that yet.
Thanks

 

[Cameron Sinclair]

Does anyone have a clear readable wiring diagram for a JLG 45HA machine??