JLG 60HA Unable to use any controls from Platform plus engine dies

I have a JLG 60HA. I haven't used it in a while, approx. one year. It worked fine when I last used it. It is a 2WD with Ford industrial engine. PQ controllers. The lift operates just fine from the ground. When I move the switch to platform, the engine slows to idle, the blue light on the platform begins to flash and the engine continues to run smooth at idle as I climb into the basket. Once I'm in the basket, I depress the foot pedal, the engine continues to run at idle speed, the blue light stops flashing and none of the controls work. If I keep the pedal pressed down the engine will die after a short period of time; approx. 7 to 30 seconds, the amount of time varies but it always dies abruptly. If I hold the pedal down, and keep one of the controls in the stroked position it seems like the engine will die sooner than with just the foot pedal depressed but since the time varies I am not sure about that. Also, the alternator is not charging. I have continuous 12V on the "A" terminal but just 1.3V on the "I" terminal when the ignition is turned on. If I unplug the connector from the alternator the voltage goes up to 12v on the "I" terminal. I ran a jumper wire from the "I" terminal directly to the battery to force the voltage up to 12V (there was 1.5 amps flowing on that jumper wire to hold it at 12 volts so, it wasn't a dead short) I thought that maybe low voltage on the "I" terminal would cause the machine to not operate from the platform, that's why I put the jumper in the force the voltage higher. Doing that did not change anything, still no platform control and the engine dies. Since the alternator is not charging, the system voltage was at ~ 12.4V while the machine was running. ( I had a battery charger connected charging at just two amps to maintain the battery). I then went so far as to connect a running vehicle with jumper cable to the JLG to get the system voltage up to ~13.7V but even with the JLG system voltage at 13.7 volts there was still no change, no control from the platform and the engine will die if the foot pedal is held down for a period of time. If I quickly release the pedal as the engine is about to die, the blues light starts flashing again and the engine continues to run fine.

Have you ever checked the voltage in the basket? If it drops below 11 volts, things are going to stop working. The engine will die at about 10 volts.

Ok. That's good information. Thank you. I will check the voltage in the Basket in the next hour or so and reply. Thanks again!

I just checked the voltage in the basket. The voltage is 11.78 on the circuit breaker inside of the wiring box. There is approximately .6A of current flow on the wire delivering powering to the circuit breaker. When I push the pedal down the voltage immediately dropped to 1.6 volts and current flow to the circuit breaker drops to .25 amps. Also, like I stated in my original post, the blue flashing light on the basket stops flashing when I press the pedal and begins flashing again when I release the pedal.

There is a mistake on my previous post. Voltage reading on on the circuit breaker is accurate but the current is wrong. I was actually measuring current on one of the circuits that is fed by the circuit breaker and not the wire delivering power to the circuit breaker. Upon further investigation, I found High current draw, approximately 37 amps, on the orange wire leaving the circuit breaker when the foot pedal is pressed. There is no current flow on the orange wire when the pedal is not pressed. The orange wire goes to the foot pedal. I am going to continue troubleshooting now. I just wanted to correct my mistake so you had accurate information.

I found the problem. It was a faulty switch inside the foot pedal. I temporarily installed a regular household three-way switch and the controls are back working. The switch was routing battery voltage to ground hence the 39 amps of current flow in my earlier test causing the voltage to drop. I am surprised the circuit is not fused somewhere to protect against that amount of current. I know there is a circuit breaker in the basket wiring box that the current flowed through but it must have a higher tripping point than the 39 amps that I read. I have never seen any fuses on the machine so maybe it just has circuit breakers. Also, there must be some sort of a resistive load in the circuit to regulate the current to the 39 amps that I read because the faulty switch appeared to be routing the approximate 12 volts directly to the ground lug. I suspect corrosion inside of the faulty switch and that may have been limiting the current. One thing that I did notice that isn't quite right is that when I move the creep switch to the snail position the only functions that work in the creep mode are, main lift, up only and Tower telescope, down only. When I move the PQ controller for swing I can feel the basket starts to sort of jiggle but it never actually moves. So, only two of the four p q controllers work in the creep mode and each of them only work in One Direction. If you have any insight regarding that issue please let me know. It's nice to have the machine mobile again. Thank you for steering me to voltage checks in the basket.

Glad you found the problem. Did you see any diodes in that foot switch? I remember there being some, one of them could be cooked. Those creep switches/knobs never did work well even when new. Again, you're controlling voltage, so the problem with your creep could tie back to your charging system issues.

No, there were no diodes inside of the foot switch. Just a couple of single pole double throw switches that operate in unison. The normally closed contact on one of the switches had 12 volts on it from the common terminal. The switch was not opening when the foot switch was pressed so that 12-volt remained there. There was a jumper wire that ran from that normally closed contact over to the normally open contact on the other switch. When the foot pedal was pushed that normally open contact was closing and connecting to ground thereby sending 12 volts right to ground . That's interesting regarding the creep function. I will get that alternator replaced and see if it improves the operation of the creep function. I think it was working before but I'm not sure. I will post the status of creep when I get the alternator replaced. I suppose me standing in the basket holding the foot pedal down repeatedly for durations of time sending 40 amps to ground probably texting the alternator to capacity didn't do it any favors!

dmar JLG 60 HA said:

I found the problem. It was a faulty switch inside the foot pedal. I temporarily installed a regular household three-way switch and the controls are back working. The switch was routing battery voltage to ground hence the 39 amps of current flow in my earlier test causing the voltage to drop. I am surprised the circuit is not fused somewhere to protect against that amount of current. I know there is a circuit breaker in the basket wiring box that the current flowed through but it must have a higher tripping point than the 39 amps that I read. I have never seen any fuses on the machine so maybe it just has circuit breakers. Also, there must be some sort of a resistive load in the circuit to regulate the current to the 39 amps that I read because the faulty switch appeared to be routing the approximate 12 volts directly to the ground lug. I suspect corrosion inside of the faulty switch and that may have been limiting the current. One thing that I did notice that isn't quite right is that when I move the creep switch to the snail position the only functions that work in the creep mode are, main lift, up only and Tower telescope, down only. When I move the PQ controller for swing I can feel the basket starts to sort of jiggle but it never actually moves. So, only two of the four p q controllers work in the creep mode and each of them only work in One Direction. If you have any insight regarding that issue please let me know. It's nice to have the machine mobile again. Thank you for steering me to voltage checks in the basket.

Click to expand...

How did you wire a house 3 way switch to “test” or temporarily operate the lift? There are 4 wires in the foot switch.