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Electrical Issue Bucket/MAn Lift

Mobeus

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Mobeus New Member

Mobeus

Posted
Posted

Hello,

 

I realize this may not be the proper forum but my issue only pertains to the truck Platform.

I have a 99 C3500 HD with 6.5L TD.

I have a bucket/man Lift attached.

My problem is the 12V motor that runs the pump for the hydraulic systems isnt working.

a couple of weeks ago I noticed the battery indicator would got all the way up into the red unless I turned the high beams on as well as the fan while driving.

So I replaced all 4 Batteries.

at this time the motor was working fine and also worked after replacing the batteries.

Now out of nowhere the motor no longer functions.

I tested the connections at the terminal on the motor and im getting 14.5 Volts with the engine running. However the motor does not work. I can hear the Solenoids for the different cylinders opening and closing when iactivate the controls.

So I had a buddy pull his truck next to mine and I connected jumper cables directly to the 12V motor with the other end of cables connected to his battery. Still the motor did not work.

SO I assumed the motor was bad and removed it.

On a whim, with the motor removed from the truck I hooked it up directly to a 12V engine starter and the thing started working.

Confused and thinking maybe it was just frozen or something and maybe the jostling from removing it from the truck unfroze it, so i put it back in the truck and tried again...and this time again it did not work...

So I removed it and tried again with the 12V charger and it worked.

Im very confused because I get 14V at the motor terminals and it just isnt working. and also because it wont work when its in the truck but will if I take it out and apply it to the charger or even jumped from another vehicle...

Can somoone please help me figure this out as this truck is how I feed my family and I must get it fixed soon.

Thanks so much in advance.

 

Green 1364 Enthusiast

Green 1364

Posted
Posted

Wondering if your ground is good to the motor....Also, in those bucket lifts there are safety's such as a weight limit that may stop the motor from working. For example an over weight condition usually stops it from working. Without seeing a print of what you have it's hard to say though.

 

Also, if you have a blocked hydraulic filter that can cause it. Very cold hydraulic fluid can also cause a pressure switch from making. If you can get the vehicle in a warm garage for a while might help.All depends how the system is wired.

Green 1364 Enthusiast

Green 1364

Posted
Posted

If you can find a print online of the hydraulic, electrical circuit I will look at it deeper and try to help more. Post it on here or email to me. It just seems something in the circuit is telling it not to turn on if it's wired that way. Also remember when you removed the pump it had no load on it because it wasn't connected to the pump. If it's very cold where your at it will make the hydraulic fluid thick and hard to pump.

Mobeus New Member

Mobeus

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I checked to see if it was seized..it spun when I took it out of the truck and hooked it to the charger.

I dont believe it is a safety switch because when I test the voltage where the + and the - attach to the motor I get 14 Volts but the thing doesnt spin...it doesnt even sound as if its trying to spin.

if it were a safety switch there would be no voltage at the motor posts.

I think it may be a bad ground but even that doesnt make sense to me because when I jump it directly from the motor posts to another vehicle it still doesnt work...it only works when I physically remove the motor from the truck and and hook to a 12 Volt source. I figured it would work by jumping to another vehicle but no luck. Even if its just sitting in the compartment with no wires from the truck connected just the wires from another vehicle it still doesnt work. I thought it would use the ground from the other vehicle.

IF I remove it from the truck and jump directly to another vehicle it works.

I thought maybe there was a short from hot to ground but the truck runs fine and electrically every thing else works fine in the truck.

Mobeus New Member

Mobeus

Posted
  • Author
Posted

If you can find a print online of the hydraulic, electrical circuit I will look at it deeper and try to help more. Post it on here or email to me. It just seems something in the circuit is telling it not to turn on if it's wired that way. Also remember when you removed the pump it had no load on it because it wasn't connected to the pump. If it's very cold where your at it will make the hydraulic fluid thick and hard to pump.

I thought the same about the temperature but this happened before we got the cold spell...also just 2 days ago I tested it with the charger outside and it worked. so I dont beleive it is temperature related.

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