Kevin, before I got to this pallet jack, someone returned it to service. It came back a week later with C 57 and C66 ( both dealing with brake circuit). I finally determined the fault to be a bad 24 vdc battery. Below is the detailed info.
C 57
Fault code on Toyota pallet Jack
A bad or failing 24 vdc battery showing 40% or less on the display, may cause the following on the Toyota 8HBE30 long double jacks:
1. Ticking / rattling noise (due to electric brake not fully disengaging.)
2. Brake locking up and throwing operator from jack.
3. Fault code C 57 or C66 displayed
4. Pallet jack speed reduced to 1MPH.
- Diagnose by connecting a DC volt meter to read battery voltage with battery connected to pallet jack.
- Note the voltage ( probably about 23 vdc )
- In an area safe to accelerate, accelerate full throttle and watch the volt meter. If the voltage drops below 17.0 vdc and stays during travel, it is too low.
- When this happens the pallet jack computer recognizes the voltage is too low, the brake circuit opens, code C57 or C66 is set, the brake applies, the operator is thrown, and speed is reduced to 1 MPH to travel to the battery charging area.
Hope this helps our fellow technicians.

Kevin, Thanks for the reply I'll check down that road to see what I can find.
With my other duties and assignments it may be a few days before I can get back to the shop.
Ben

Brake Coil Driver Open or Shorted..........