865-243-666 Voltmeter Horizontal 0-20 Volt With Battery Test Alternator Test And Printed Circuit Board Assembly. This circuit board and meter have been calibrated to each other. No other adjustment is necessary. Replace both meter and circuit board to ensure proper operation. If your circuit board has 2 black wires and 1 blue wire, substitute as follows: Yellow wire for short black wire and red wire for blue wire. See 247-022-666 for meter only.