Knowledgebase Contact Us


If you can’t get your motor controller to work, we’ve found that following these troubleshooting steps often helps to find the problem;

General problems:

Fully 50% of our support issues can be traced to one of these seven issues.

  • Have you got full battery voltage across the B+ / B- terminals on the controller? Check for crimp terminals gone bad.
  • Is the ignition circuit, potentiometer, and reverse wiring ok? See this video for details.
  • Is the “high pot lockout” feature activating? [not Porter or DNO].
  • Are the fuse tracks on the circuit board ok? Most of our controllers have these designed into the circuit board to protect it against external short circuits. See the relevant manual for details.
  • If you are getting P2 or P3 pot faults, or odd low speed behaviour, has the potentiometer been replaced? They do wear out, see this page for more details.
  • Are the control cable plugs in good condition? The example in this picture caused all sorts of intermittent problems as the internal pins shorted out

poor IDC connection

They’re cheap to replace, and can be ordered here. Make sure you are using the correct size of wire [7 x 0.2mm], anything larger can cause the pins to short internally.





  • Our 6 and 8 way multicore control cables can have either a white or black dummy “filler” that looks like a wire but doesn’t actually have any copper inside.

Model specific problems:

If you’ve checked those general points and are still having problems we’ve now divided this page up into sections for each of our product families, please click the link to the relevant one…

Pro-100, Pro-160, Pro-360.





4QD-200 / 300

If you need help with troubleshooting, we’re happy to talk, but before you phone us, please download and complete the fault-finding sheet from the relevant section. Without that information we’ll be flying blind, having it ready will help us to get you running again a lot faster.

We also have a controller test board, it works by temporarily taking the place of the normal control wiring, and helps to identify and isolate problems. These are available free of charge to all model engineering and locomotive clubs, are available for purchase here, and can be loaned if required. Here’s a list of all the clubs that have one.

One last point, the majority of mosfet failures are due to electrical noise from the motor brushes. We strongly advise fitting suppression components  and making sure your installation follows these guidelines.