Just bought an '83 mitshubishi 4x4 diesel pickup. Pretty good shape and am enjoying working out a few bugs. I am 63 and have been a shade tree truck mechanic most of my life, but just on my own stuff. To start with this truck occasionally makes a loud buzzing sound from a silver box on the passenger kick panel. Glow plug relay? It does this about one in three start ups and lasts way too long. Eventually goes off randomly. I have 3 other older diesel vehicles and I have installed manual glow relays with solenoids. Is this what the buzz box is?" Thanks in advance, GB