An 85 K30 should have a voltmeter, not an amp gauge. Disassemble and burnish the ground connections to shiny bare metal. Concentrate on the I/P harness connections to the instrument cluster PC board, the ground connections to the park brake frame under the dash at the left kick panel, the braided jumper between the firewall sheet metal and the back of the passenger side cylinder head, and the battery to engine ground cable. Check the PC board for cracked or peeling foils. Make sure that none of the I/P harness black ground wires are severed.