fuel pump posted by TJSB on February 23, 2015 at 06:30 PM
Message
controller is bolted to the car body and has a good ground. Without that it won't work. The fuel pump is controlled via a ground signal. It always has B+. The only way it can get its negative voltage is if the chassis of the FPC is grounded. It looks like the fuel pump is being sent a positive voltage from the FPC but that's only because the positive voltage to the FPC is on the same line as the voltage going to the FPC, not coming from it. The negative side of the voltage is what comes from the FPC and is controlled by it.