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Fitting a Porter to a PDQ Power trike

The old PDQ wiring used a Scientific Generics controller, a lot of which are failing after many years service. The Porter 5 is a good replacement, here are some steps for fitting a Porter to a PDQ power trike.

You will need the following parts:

  • A Porter 5 or 10 modified with a vertical 5 way IDC connector instead of the horizontal one [we have a version available with this already done].
  • A Magura twistgrip throttle or other potentiometer arrangement [please note we have not yet managed to re-use the original PDQ hall throttle]
  • A DNO heatsink [or other aluminium plate].
  • 8mm x M4 pan head screws [4 off].
  • A 5 position “choc block” screw connector.
  • We also recommend having a voltmeter to hand! PDQs are getting quite old now and every one that we’ve had in the workshop has needed some level of diagnostics.


  1. Remove the existing control box and open it up, remove the old Scientific Generics controller.
  2. Modify a 4QD DNO heatsink so that it fits the box.
  3. Modify a Porter 5 by changing the horizontal 5 way IDC connector for a vertical one [we can do this for you].
  4. Mount the Porter onto the modified heatsink.
  5. Cut off the connectors inside the box for the throttle, and brake switch.
  6. Mount the Porter and heatsink inside the box as shown – we used 8mm x M4 screws with a couple of washers so that only half the thread of the brass insert is used.
  7. There are at least two versions of the box with different hole locations. When drilling the heatsink take care not to let metal swarf and dust contaminate the circuit board.
  8. Replace the old hall effect throttle with the Magura twist grip potentiometer.
  9. Use the “choc block” screw connector to wire up the throttle and brake as shown below. Be aware that some PDQs have a brake switch that is normally open, if yours is like that you will need to omit it from the circuit.

10. Close up the box, and mount to the frame using the other 8mm x M4 screws.

Notes: We have seen some PDQs that have the blue wire from the battery box as the positive [B+] line instead of the brown we’d expect – made us scratch our heads for a while!