To check the switch, first check the power source, (fuse # 15,16 amp fuse.) Check switch with test light or voltmeter,#2 pin should have 12 volts at all times, switch in on position, #1 pin should have 12 volts applied. You can accomplish these voltage measurements by partially unplugging harness plug from switch and using your voltmeter or test light. Lighted knob for switch should also glow when system is on.

Turbo240