My friend Alister who is an Electronics Engineer has now tested my working spare Turn Signal Module & he wanted to share his findings:
He is going to suggest a retro fit solution in due course as Voltage spikes sure seem to be the problem here.
From Alister:-
The fault seems to be caused by a failure of the integrated circuit CD4072.
I have not fully copied out the circuit diagram but am 75% there and this fault showed up.
Its input pins go to the loom directly so any voltage spikes will destroy the 4072. Internal diodes inside then conduct power from the hazards circuit to the main ignition 12V feed hence a motor will carry on running with the ignition key removed.
As per usual, you are welcome to let the others know.
