FixaForklift.com

I have a older Mitsubishi NYK 48v Forklift
Model FB15P
Intermittent no drive, forward or reverse, contactor will close but no movement. The tips look fine. Batteries fully charged. Some days it works great other days won't drive at all.
Tilt, hoist and side shift all work as does steering.
It will close the contactor and run in high speed if holding the pedal to floor after 10 seconds.
Any ideas where to start looking?

Hello and welcome to fixaforklift.com

This sounds like a definate contactor issue, it is also possible that the coil is weak, it is best to check voltage going to the drive motor when trying to select it into forward.

You should lift up the drive tires,
with your meter stab a negative wire onto the negative side of the battery, then with the positive lead check voltage going into the drive motor, if 48 volts is going to the drive motor and it is not spinning, it sounds like you have an intermittent issue with the drive motor.
A bad wire going to the drive motor or even the tip of the wire going to the drive motor may be loosing contact as well, if you suspect you have a bad drive motor you can put your meter on ohms and put the negative lead on the drive motor and the positive lead on the other side, with both those wires disconnected, if it read resistance you have a short inside the motor if it read OFL thats normal.

It sounds like its an issue between the contactor and the drive motor.

You will have to remove the battery to perform the proper test and to physically look at the tips of the leads going to the drive motor.

Thank you for the advice.

I checked the for power through the contactors it has 51.1 volts through both forward and reverse. The motor reads 51.1 volts on all three connections with the meter grounded at the nag battery cable. I pulled the wires from the motor and checked for continuity it reads OL between the connections labeled AA - F and AA - FF. There was some reading between FF - F. All the wires appear to be in good shape and the connections are clean.
With the wheels blocked up and testing for voltage, holding the accelerator down with forward selected the forward contractor will close with no movement then the high speed will close after 5 - 10 seconds and wheels will spin at high speed. Maybe whatever controls the speed is bad?

Let me see if i can get a diagram, i will probably need the serial # please post one if you have one thanks

Thank you

The data plate reads:

Nippon Yusoki Co., LTD.
FB15P S/N 22110459
CASCADE 55D-SS-91A

I will work on it today, if you register as a user you can get email updates when i reply to this forum by the way thank you

I dont see a model number fb15p i am scrolling through my truck list from Mitsubishi , the closest i see is fbc15, fbc15k, and so on

Here is a picture of the data plate. No wonder I could never find any info on this machine : ) I have one photocopied page of a wire schematic that was in the truck when I got it.