Possible causes of -51 on NPR

Defective capacitor.
- Check capacitor bank per component checking section.
- Check for loose or open connections in capacitor circuit.
*Misadjusted / defective steer interlock switch.
- Check to insure that the steer interlock switch closes after
the line contactoh power tips close. Repair or replace. -Defective steer control.
- Disconnect the positive cable and 4PL plug from the steer control. If status code disappears, repair steer control.
-Open circuit in capacitor precharge circuit.
- Check for loose connection or broken wire (WHT) at #3 REC
heat sink or along the length of the wire.
- Check for loose or corroded connection at terminal PZ14.
- Check for loose connection or broken wire (BLACK) at 1FU
power fuse or along the length of the wire.
- Check for loose or corroded connection at terminal PBl.
*Unsuppressed voltage spikes.
- Check that any and all coils, including horns, that are
present on the truck have the proper voltage suppression. - Check that the static drag chain is present on the truck and
dragging on the floor so that it keeps static electricity from building up in the truck.