Low Air Light

Not a complicated system there. There are 2 low air switches in parallel (primary and secondary), wire 305 goes from the dash to the low air pressure switches. Wire 239 is on the other side of the switches to ground. To use a voltmeter to check grounds, put the red probe on battery positive and the negative at the ground that you want the check. Battery voltage manes a good ground. No, or low voltage means a bad ground.

1. Using a voltmeter, verify that wire 239 is a good ground at both switches. If the ground it bad find the bad spot and fix it.
2. Jump a switch, this will ground wire 305 as if the switch was closed (low air). Then to the same to the other switch. The light should come on.
3. With a switch jumped, check for a good ground at the light bulb socket. If there is a bad ground at the socket, but a good ground at the switches, check the wire and connections in wire 305.
4. Check voltage at the bulb socket. Low or no power, you have a problem at the light bar side of things.

 

They're in the manifold there behind the clutch & brake pedal. There should be little metal tags on the wires with stamped #'s.