v3.8 p259 protection diodes

[Kamuto]

hello, maybe someone knows way, what modification needs to be done (without removing diodes) that relays wont be triggered when ignition is off (relays have 12v feed when ignition is off) same with stepper outputs, anyone?

[lezsi]

I faced similar problems many times on racing cars where fans, pumps, etc. are feed from different voltage supplies. 
The easiest way to cure the problem is to cut the diode's common trace on the PCB -not an elegant one, I admit.

If you want to keep the diode-protection however, you'll need to reroute this trace to a not switched +12V, like the flyback in ideal situations

I'd vote for omitting these diodes as good quality automotive relays (like all OEM BMW) always have a protection diode inside.