MS43 e30 no ign power after clearing codes

[Clay simon]

Howdy all
i have a m54 swapped e30 convertible, I hooked everything up and the ecu needed power on pin 7 of the X60001 connector. I took the power for the heater of the down stream o2 sensor and ran it to said pin (both are 12v 30a). Everything read fine and I could see codes and identify the ecu after. Once I went to clear codes, I lost connection to the ecu and went to test power, everything that once had ignition power no longer has voltage. As far as I could tell everything has continuity power and ground sides respectively. All fuses in the box and the 5 main fuses for the ms43 is all good, all relays are fine as well, what would be missing for me to not have ignition power anywhere in the car. Only thing that works is the dash lights. All ecu wiring has 0v

[Northern]

Ignoring the spam bot bump... is the O2 heater not switched by the ECU? I have no idea when it switches on/off, but unless I'm misunderstanding, it feels sketchy to apply flashing voltage to the ECU, from the ECU, from a power source that may switch itself off at an unknown time.

[TobyB]

MS43 has always hot supply, but switched ground for o2 heaters, so that 'should work'.

https://bmwteka.com/wds/en/e46/6837f0a2

That said, all 4 heaters run off the same fuse in the DME bin (#4) so doing so is kinda askin' for it, as the oxygen harnesses
have a real habit of getting up against the headers, melting inside the fiberglass jacket, and blowing the fuse.
(auto cars also use that fuse for the EGS, so the transmission stops shifting then, as well.)

Losing the DME when clearing codes sounds like OP used a Foxwell, he snarks...




t

[Clay simon]

Found issue, crack was found in fuse that powers it