I think there is some link to the heater fan... my second board was modified after failure (simply the diodes for the back emf being under spec as standard) and then started to misbehave in an alarming fashion... rev counter not working along with some other gauges, but in an intermittent way. That board had some blown tracks so I have modded my second board with new diodes but intact tracks and I just get the rev counter hang on switch off. Leaving the full ecu cycle makes no difference on mine
