Hi Dave and
to the forum,
The Magic Pie 5 controller will only work with a Magic Pie 4 or 5 and will not work with earlier Magic Pies.
I gave up trying to upgrade an early MPIII using a pre-production MP4 vector controller as I could not get the motor to run properly:
I decided to test the wheel in the bench vice before refitting it to the bike, which turned out to be a wise decision.
I connected the controls and battery and tried the thumb throttle. As I gradually pressed it, the motor suddenly started at full speed and did not alter the speed until the lever was released.
It seems to work just like a simple On/Off switch with no variation in the motor speed whatsoever (either full speed or nothing).
If I pull either of the brake levers and then try to use the throttle it will not run (so the brake switches are both working) but if I pull either of the brake levers while the motor is running it does not cut the motor and does not disengage the cruise control when cruise is activated.
I also discovered that if I open the throttle and then pull a brake lever, I can release the throttle completely and the motor will continue to run at full speed for as long as I keep the brake lever held in. Releasing the brake lever then causes the motor to stop.
If I re-apply the throttle before the wheel has completely stopped it really jerks the motor and a couple of times it has even caused it to cut out completely and would then not restart until I disconnected the battery and reconnected it again.
GM had apparently modified the stator windings and hall sensor positions to suit the sine wave controller, but the changes to the windings meant that the sine wave controllers were not compatible with "non-vector" motors.
The MP5 controller will also work with a Magic Pie Edge or Smart Pie vector
if different firmware is installed
(but it will not work with an original non-vector Smart Pie).
Unfortunately, the MP5 controller is unlikely to work correctly with motors that were not specifically designed for use with Vector controllers.
However, if I've misinterpreted your description, and you are actually using a 16" MP5 with its original controller mounted externally, the problem you are experiencing must be down to the extended phase wires
(or possibly an incorrect hall sensor configuration?).
The 4 blinks indicate that the stall protection function has been activated because the motor has been stalled for too long.
Alan