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- STRONGLY recommended: BY399 throughole (or STPS340U SMB) diode between injector shared +12V BMW88/87 (anode) and BMW88/26 VBATT (Cathode)
- even an 1n4007 is better than nothing (this diode is shorted by the DME relay anyway, but during relay switching, it does not hurt).
Alternatively, it might make sense to connect EC36/23 flyback rail to BMW88/26 (VBATT=node30) rather than BMW88/87
- if there is a 18V transient diode to GND, or a diode from BMW88/87 to BMW88/26 (inside ECU or in harness) it makes little difference, otherwise it might be safer
BMW88/69 Fuel pump relay solenoid pulled down to 0.2V by EC36/15 p259/ch5 output
- this should safely activate the relay
- you can try to disable fuel pump, and configure misc2 output as test (or even try all other p259 channels, just in case).
- Can you measure at the ECU output pin (from 12V as a base ?)