I am working on cutting out all the BS on my harness for my race truck. The engine compartment fuse box has a diode for the PCM. 1st off, what is a diode? MY buddy told me it was to direct current in one direction. 2nd, do I really need it? I'm sure Ford put it there for a reason, but I just want to make sure if it is completley neccessary because I would like to get rid of as much as possible. Thanx.