MSefi.com read only forum (Jan.15,2018)

For installation of an MS, I need to reverse the fuel pump control signal that MS puts out. MS grounds a signal to command the fuel pump to run. My car's fuel pump circuit -- at the particular control wire that I want to use -- requires an open circuit to run the pump with a ground to shut the pump off.

I can do this with a mechanical relay but am looking for that little elegant circuit that will perform the same function. The circuit would take the MS fuel pump signal as input and operate on the OEM pump control wire -- open circuit run and grounding to shut off.

Does anyone have a schematic for a circuit to accomplish this?

Brian
Chester, VA

what is wrong with a relay? MS can't handle the current that a fuel pump draws directly. You may want to test and see how much current the fuel pump trigger wire draws. A relay would be your best bet.

A relay would work, for sure. But a circuit would be more elegant -- and sometimes that counts.

The OEM control wire I speak of comes from the fuel pump relay terminal 85. When you ground that terminal, it shuts the fuel pump off. So the circuit would not be handling fuel pump loads.

I hear tell that a triac might be just the trick. But I do not know how to make that work.