removed accel unit from pedal. microswitch was misadjusted and did not interupt contact.readjusted it and now clicks at first touch of pedal and hum is gone in forward or reverse.
hum starts when pedal is first touched but then contactors drop out within 1/4 second so still no go.
doesn't look like accel unit was ever tempered with as white paint on screws still intact on circuit board and microswitch.

will put it back on blocks weather allowing tomorrow and run all the tests following service book.

yeap.and when truck runs,the motors do as they are supposed to..reversing or slowing down depending on steering angle.
also tried it while driving and you can feel it as well.
it did drop out a few times when hitting the first step on the steer cam.resetting the f/r lever got it going again.as usual these drop outs happen occasionally assuming the truck even runs.
went out to try to get it to move again and still no luck but tomorrow is another day?

One more thing..........did you block the lift up and check the rotation of of drive motors as i posted earlier?

sure did and they all check out good going from o to infinite upon closing and opening but will check them again along with accel unit( thought i heard the microswitch in it once but not too sure)

Did you ohm the switches out on the cam? To make sure they are closing and releasing?

yes,the steering pump is still not connected at the relay so it doesn't drain power while i'm testing things and makes it easier to track other noises.
the thing is that, it always hums whether it runs correctly or not so had no way of knowing if it was correct behavior seeing it's my first foray into the electric forklift world.
i'll test the accel unit for proper operation now that i have a service manual and report back.you mentioned a trick to adjusting this a while back?
you are correct in that checking main drive motors is a pain.had to remove the tilt cylinder and steering pump assembly to get to motor shrouds
did check the 4 steering cam microswitches a while back and all operated normally(closing and opening as cam pushes or releases them).
stay tuned.

It should not be humming when just simply selecting f or r. I would check my accel pedal adjustment external stops. This unit has an electric motor for steering so this rules out pump hum. The hum you hear is probably the scr that is cutting on when you are selecting travel direction and should not be heard unless you are depressing the accel pedal. Try and adjust the release stop for the accel pedal to get the scr hum out. The steer cam has several micro switches and these should be checked for proper operation.

finally an update.checked brushes for arcing and general shape.lenght is within tolerance with minor variations on different brushes(+/_ 1mm) and no arcing when running.powering truck with a decent battery now.voltage doesn't drop to below 24v when under drive load.
sometimes and as before when turning sharply left or right(when steering switches are activated by steering cam) the drive motors will drop out.resetting the f/r switch will get things going again.drove it 3 blocks and all was good then parked it.the next day contactors drop out again at slightest touch of pedal.25.7v on battery so not a charge issue.will be looking at contactor detecting unit for proper voltage tomorrow.
is this truck supposed to hum(fairly loudly) when f/r switch is engaged and the pedal is not depressed?
if only i could find a SCC-02C EVS analyzer:(

And i hope this is a 3 wheeler LOL

One other thought you might want to try and this involves jacking unit up and blocking unit to get drive tires off ground. Remove floor board and check if your motor brushes for drive tires ( 2 ) are good and not arching. they are a pain as the motors are stack one on top of other.Sometimes they will not make commutator contact and drop contactors out. Batteries are a problem also as you are not getting but only 5 minutes run time and will travel no faster than walking speed. Best to also get steer tire off ground and run lift while turning left and right. When turning right while sitting on lift, the right drive tire should slow down and at almost lock, it should turn backwards. Same is true when turning left.....left should slow and at lock turn backwards. As i said check yer brushes and let me know what you find out.

figured this would ruffle feathers:)i know mine are but i just bought it like that(batteries and all).
i'll get you exact numbers but the dash volt meter doesn't drop into the red zone as i barely touch the throttle since it"s just tests conducted in the driveway with the steering pump relay disconnected and no lift pump actuation.i strictly use the traction motors as this is where the problem lies.
i'm hoping you're correct in that the golfers can't keep up but???i fully charged them and it ran(all at walking speed) for perhaps 4minutes then started acting up.let it rest a few minutes and it would go again for a minute but sometimes less.steer a little hard left or right and it shuts down.got it back in the driveway by turning the key switch on,flooring accel then putting lever in forward.if i put lever in forward first then accelerate the contactors would drop out.
2 days later it ran fine for about 3 or 4 mn till i parked it.not pushing my luck :)
low voltage lock light has not come on and when traction shuts down,lift and steering still function without straining.
not much info to go on but i will do a more thorough test in the next couple of days.
the symptoms are random time wise,just like whether the steering is turned or not.sometimes all is ok then next seconds it's not.
kinda points at low volts or a loose connection but??
drives me nutssss.

Do what??????? 3 golf batteries? sensitive? yes as most electrical things are and especially cards and choppers. The unit should have a pump cut card located on it. Do this.......... back probe the positive and negative cables off the batteries with volt meter and when driving it under load ( hard accel) what do the volts drop to? The hydro pump will be the big energy user Approx 350 amp dead headed. I am not sure what AH rating those batteries have but it isnt helping the situation. It will be hard to diagnose problem without proper battery and amp hour rating. Never seen a set up with golf batteries before on a sitdown rider as such. I am suspecting unit is dropping contactors due to low voltage as the golfers cant keep up. The golfers are cannot maintain a constant and reliable voltage range due to capcity is what i am thinking. You do not want more than 3 to 4 volt drop when accelerating. The pump cut card works by kind of averaging the voltage and going into cut. Let me know what the voltage drops to. There sould be a switch on dash thats marked power /eco. Perform the test set on power.

i'll open the console and check it out.the loss of drive power is intermittent.sometimes it'll shut off when you back off throttle completely.reseting the f/r lever gets it going again but sometimes it doesn't.
you can always hear the hum of the controller and the contactors close but as soon as you touch the accel the contactors cut out and hum stops.reseting the f/r gets the hum back on and cycle repeatsthis happens in forward or reverse.are these trucks very sensitive to input voltage/amps?
it's currently running on 3 8volt golf cart batteries.i'd like to sort this out first before splurging for a $3k battery.
the forks and power steering always function.
thanks.

Sir this lift does have a cabin relay that is located in bezel with key switch. But if truck always comes on, cabin relay is good. Possibly you had a stuck or welded tip that freed up when you were wiggling wires. If truck acts again, check tips and as i mentioned before, remove the forward-n-reverse swith and take out the 4 phillip headed screws. Inside you will find leaf contacts. Check for cracks in leafs or metallic flake bridge on leafs. Also the throttle may be not returning all the way. These trucks have a throttle module that can be a real pain to set up if tinkered with and not familiar with it. I do not suggest adjusting anything in them unless you have set one up before.

truck always comes on,it's only forward and reverse that acted up.
moved the wiring around a bit and reconnected the control module a couple of times and all seems ok but for how long?
seat switch was bypassed and no cabin relay on this unit.
anyone with an electrical service book?
btw,unit was built july 1985.
i saw a service manual for a 1983 model.any similarities?

Check your seat switch and cabin relay for no power up. Relay is located underneath keyswitch bezel. Check battery voltage first. Should show atleast batt volts or more (count yer cells and double them...... 12 is 24v, 18 is 36v ).While bezel is off, be good time to check f-n-r switch and ign switch.