1993 GMC Sierra • 11,300 miles

Just finished replacing brake lines, all brakes and fuel lines except 1/4" vapor line. Put 5 gallons of premium gas and installed new Interstate battery. The 4.3 L turns over well, but only has power at the starter and electric internal fuel pump. No power at dash, horn, radio, lights and suspect no power at the coil.
It's a plain truck 4.3 L, auto trans, power steering & regular cab, 2 wheel drive with 8 ft box, no other accessories.
The truck sat for 3 years prior to the current work, I've had the truck since new.
Can you point me in the right direction?
May 29, 2012.

If there's a smaller positive battery cable bolted to the under-hood fuse box, check the connections to be sure they're clean and tight. Work your way along that wire with a test light to see where voltage is lost. Do that with the head light switch turned on so current is attempting to flow. That will make the bad connection show up.

Check for voltage on the fuses under the hood. If it is missing on some fuses that should always have it, you might suspect a corroded rivet on the brass strips under the box. Also look for a wire corroded off under the fuse box.

May 29, 2012.
Have you check all the fuses and fusible links?

May 29, 2012.