I have a 3 wire MAF on my car. I have the wiring diagrams. There is a 12 volt battery , ground and a signal wire. I checked with a meter and the signal wire has a 4.75 volt signal. When I series the maf/map I bought the pot adjusts the voltage not going to the ECU but the voltage going to the MAF. I tried switching the the leads but got the same results. Any ideas?