[patrickt]

It does look like the other side of the ignition light eventually gets its 12v+ through the gauges, which is indeed that fuse #3. So, if the fuse is blowing, then there's a short somewhere on that line. What I would do is pull the fuse #3 entirely and set it on the work bench. Then cut the Y/R wire right before the "I" terminal of the voltage regulator and run a clean, fused, wire from the battery positive terminal to the "I" terminal. Then fire up your car and see if it charges properly. If it does, then work your way back on the Fuse #3 line, starting with the fuel gauge, then over to the tach, then back to the wiper switch and search for the short. On the other hand, if doing that blows the fuse on your test line, then the fault is on the voltage regulator side.