Hi blackie,

Does the truck lurch then fails safe or just increase in speed?

If it lurches forward and the fails safe then you may have an earth fault on the power part of the traction and hydraulic circuit check for an earth fault on the main thyristor on the EV100 traction controller (the power terminal that goes from the main thyristor to the direction contactor and also the bypass contactor if it has one). You may have a problem on the insulator under the main thyristor.

If it speeds up you may have a problem with the foot pedal wiring, MAKE SURE THE TRUCK IS JACKED UP OFF THE GROUND then check if the voltage on the TB1 connection on the EV100 traction logic with the foot pedal micro switch just made the voltage at TB1 (accelerator pot voltage) should be about 3.5 Volts then operate the lift switch and see if it reduces if it does you may have a short on the wiring between the foot pedal micro switch and the lift switch
Regards Shane