Ok, so you either have a dead short or weak amp meter. Most old trucks have a fuse built onto the side of the switch. Remove this fuse and try turning the headlamps on again. Do you get the same result? If so you may have a faulty switch if not install the fuse and goto the headlamp dimmer switch on the floor. on this switch you will have 3 wires, one gos to the headlamp switch the other 2 are for high and low beam. Before we test (just for grinns and giggles) mash the dimmer 1 time and try the headlamps again. Did the meter peg out? I am stoping here for a reply.

I didn't do it, no one saw me do it, you can't prove anything! "Bart Simpson"