I’m retarded when it comes to electrons, so I figured I’d ask the electrical whizzes about a few things for wiring my car. (paging LUKE_L?!)
The fuel pump on my car (among a few other things) is trigged by a ground signal that comes from the OEM SPDT fuel pump relay. The GM PCM provides a handy fuel pump trigger signal, but it’s 12V+. I’d like to introduce a new SPDT relay into the system that converts the polarity of the signal provided by the GM PCM, and uses that new ground signal to energize the BMW SPDT relay, which then powers the fuel pump. I’m curious as to which spades on each relay need to be connected where.
Physically all the wiring is being done in the electrical box that houses the ECU under the hood, so ground and key “on” 12V+ are both readily available. Both relays will be neatly mounted in that box.
This whole exercise is actually being done twice (once to energize the stock fuel pump, and again separately to power up the DME relay which controls a shit ton of things).
