I changed my ps pump and repaired my vacuum pump last year and had no electrical voltage going through my body at any time. I did not unhook the positive or negative cables as I didnt feel it would be necessary (I wont say I shouldnt have unhooked them but didnt). Hopefully I am correct in assuming that you did not have the key on and as such there should not be power going through the map sensor with the key off so I would say fwiw that that is not normal. By chance could there by a direct battery connection to some added accessory that runs a wire through that area? There are several circuits on the truck, headlights for example, that are negative switched so there is positive voltage going to them all the time. All the lights on the truck may be negative switched but do not know however I think those wires are all within a large harness and unless some sort of exposed wire is there you still wouldnt get shocked by them. I am an electrical idiot though so perhaps I should just leave it at I didnt get shocked when I did my ps pump.