Black Box

What is the Black Box on the Firewall on drivers side of my M37 and what is it's function?




Thank you,

David

On the firewall, I presume you mean on the engine bay side. That would be your voltage regulator. The M37 uses a generator and external regulator setup (old school, but reliable). Modern vehicles use a alternator that does it all in one component. If is is large and rounded top, it is the older, original type. If it is short and boxy looking with fins on the side, it is the newer solid state type.

Now, if you are looking at something inside the cab on the firewall, then I have no idea. Mine doesn't have anything but wiring harness on the firewall, driver's side.

Thanks Mike L, It's the Rectangle sort-of rounded type box with three coils inside, each having a set of points (two alike and one different)


David

David, it's the older electomechanical voltage regulator. You'll find descriptions in many manuals, the TM-8000 has pages on it. The "coils" are relays.