what is vefs

Question

on 09 ford explorer 4.6 po642 what is the vref  is that the ecm or alt not doing its job I am showing 14 volts on tool what do you think

Answer 1

14 volt on the tool the alternator is doing its job, VREF are 5 volts, , if a component needed 12 volts it would come from the fuse/.relay box and it signal would be ground, The way the ECM is designed is to give ground as a signal, and if it was to give power it suppose to be VREF which are 5 volts this helps  prevents the ECM as being a flammable unit. and to begin with P0642 means it is under voltage, your wire are some how crossed into giving 12 volts. or power that is not suppose to be there is added to it.