Kev i was soaking in what you posted last, i would check to see if some brilliant mechanic has removed the vent fitting on top of the lift cylinder and plugged it off. this could be reason the lift is pulling high amps.
The control side of traction speed, 12v goes throught door switch, brake switch, sas or belly switch, fwd or rev switch,back down to terminal bd in the middle up to contractors, any resistance in that circuit , doesn't allow enough voltage to operate coils of contractors, low bat volts, bad switches, bottom of mast switch, or bad switch above b contactor, not supplying -ve to c. All have a bearing on 3rd speed.
All lift pump motors are serviceable, and should be checked every service.brushes are replaceable.
LOL Kev i feel ya pain man. Got one them at a customers and its something every month or so. Recent repairs included new drive motor (commutator bars blown out), new batteries, new low speed forward contactor (broken) , replaced all speed switches in handle (weak internal switch springs........pull the tiller handle down and lift takes off forks trailing) and tiller harness repair (broken wires). Can't wait to see what next month has in store for me.
Update on Pump Motor blowing fuses: unhooked all power cables and ran pump from a 12V battery pack motor was drawing 110 Amps......took motor off of pump and retested motor and only drawing 45 amps at full speed......new hydraulic pump coming.
OK so I have installed new batteries and cleaned all connections and cables and have found ANOTHER issue with this anchor.....the pump motor is drawing 160 AMPS when lifting WITHOUT a load(keeps blowing the fuse)......has a NEW solenoid on it and cable connections are clean and tight.......is this motor rebuildable/serviceable? It is a sealed motor much like a starter motor......the fuse is only a 80 Amp fuse and is the correct one for the truck(LKN80).. a new motor from crown is $500+ that's WITHOUT the pump......motor only has two cables that feed to it it looks about the size of a diesel starter motor....
Yes, the 3rd speed switches the batteries from 12 to 24 volts. It takes both the B and C contactors to do that, and that is why the switch on B turns on C also. The A contactor bypasses the resistor. So 1st speed is 12 volts, and going through the resistor. 2nd speed is 12 volts, no resistor. And 3rd speed is 24 volts.
Since the batteries are being switched from parallel to series, it can cause high speed problems. If one of the batteries or connections is bad, it will run ok in 1st and 2nd because there is 2 sets of 12 volt batteries. But, when in 3rd speed, all the batteries are connected in series and if one is bad, or a cable is bad, you get nothing. There is also a fuse that if blown won't let the batteries connect in series for 3rd speed.
All the switching of the contactors is done with switches in the control handle. The turtle/rabbit just shuts off the 3rd speed and the machine stays in 12 volt mode.
It has been a while but I think that is how you go from 12 to 24v. I have some pictures of wiring but have to scan them. I will try and dig them up tonight and send them to you.
YES....I did notice this harness and it does looked to be rubbed thru some, is my next point of inspection when I get back to the truck....was just curious on the voltage going to the motor changing from 12V then to 24V when high speed does kick in...also curious about the other two Contactors B and C...B has an interlock switch on top that activates the coil for C Contactor the way it looks
Kevin,
I just had the same problem recently and it ended up being the wiring that goes from the handle to the control panel. the way the door swings open is a good spot to check all the wires.