Troubleshooting

If you can’t get your motor controller to work, then here are some troubleshooting steps that may help you find the problem;

  • Is the “high pot lockout” feature activating? [not Porter or DNO].
  • Do you have full battery voltage across the B- and B+ terminals on the controller whilst under load ? [we see a lot of problems that are caused by bad joints in the battery wiring, and also by batteries that have one dead cell].
  • Are the motor cables securely attached? Check that any crimp connections are still tight.
  • Most 4QD controllers are fitted with fuse tracks on the circuit board, check that none of these are blown [see your manual for details].
  • Tip; when we are fault finding we disconnect the motor and connect a bulb [of suitable voltage] across M- / M+ with flying leads
  • Are the control cable plugs in good condition? The damage shown in this picture can lead to all sorts of intermittent problems ….

poor IDC connection

DNO, Pro, and VTX models

Remove the controller cover, plug the control cable back in, then check the following voltages on the back of the grey 6 way connector close to the relays. Note: for the DNO take care not to press the PCB so that it shorts on the metal heatsink.

Wire colour Voltage [with respect to B-] If it’s not….
Green 0 Wiring fault
Blue 0 – 7V [Pro-150=5V] changes with pot position Wiring or pot fault
Red Approx 7V [Pro-150=5V] Wiring or controller fault
Black 0 or B+, changes with reverse switch Wiring or switch fault
White 0 or B+, changes with ignition switch Wiring or switch fault
Yellow B+ Wiring fault or blown fuse track

We’ve made up some printable check lists to help you with this on these links…. DNO, Pro-150, Pro-120

We have some videos showing how to do this on these links…… Pro-120

4QD-200 / 300 models

Remove the controller cover and check the following voltages on the pins of the grey 6 way connector on the top board [you should do this from above the board]

Pin letter Voltage [with respect to B-] If it’s not….
A Approx 11V [0V if inhibit switch active] Wiring fault
B 0V with ignition off,             11V with ignition on Wiring or controller fault
C 0 or B+*, changes with reverse switch [* can be 11V if alternative wiring used] Wiring or reverse switch fault
D Approx 11V Wiring or controller fault
E 0 – 11V, changes with pot position Wiring or pot fault
F  0V

Also check the following voltages on the back of the grey 4 way connector on the bottom board

Pin letter Voltage [with respect to B-] If it’s not….
A
B
C 0 or B+, changes with ignition switch Wiring or switch fault
D B+ Wiring fault

We also have some general fault finding tips for the 4QD series here, and some instructions on how to test the base board and MOSFETs here.

Porter 5 / 10

Remove the controller cover, plug the control cable back in, then check the following voltages on the pins of the grey 5 way connector on the board.

Pin letter Voltage [with respect to B-] If it’s not….
A 0 – 0.5V Wiring or controller fault
B 0 – 0.5V Wiring or controller fault
C 1-4V, changes with pot position Wiring or pot fault
D 5V Wiring or controller fault
E 5V Wiring or controller fault

There is a printable check list for the Porter on this link.

There are also some model specific fault finding tips in the manual for each controller.