Hello Kamuto,
We support both bipolar stepper motors though stepper chip and unipolar motors through p259, these is some documentation about this on: http://vems.hu/vt/help/v3/v3_idle_stepper_hardware.html
Regarding your trigger it might be some noise issue, but when i take into account the other effects (dashlights dimming/tuning on) i would highly recommend you debug any wiring issues first.
Best regards, Dave
dashlight was p259 who controls main engine relay
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your new diodes somehow cause it
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moved it on injector channel ant it's fine. p259 channel is working, if I shut off car, dash not dimming, if I turn ignition on and off dash is off but you can see few ligths are getting supply from somewhere
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so that's not noise. got that issue with p259 before on 3.8 boards, if one relay end has +12 when ignition is switched off p259 will trigger it with no ignition, that sucks really, had to rework all wiring to relay supply from ignition switch.