Rick is correct. The the 76 and 77 GMCs did not use a light to indicate when the compressor was running but if you look closely at the plastic covering to the lights in the tell-tale panel you can see a low air but there is no bulb behind it.
I ran a wire from my compressor and put in a bulb and found some push in terminals to connect the compressor to. Several years back I mailed an instruction sheet, a bulb and a terminal out to anyone that requested one from me. I probably sent out 75 or more. I found the bulbs in the dash panels of junkyard Volvos. You can just reach up under the dash and turn out the socket with the bulb. That socket will fill our tell-tale panel.
I got the terminal clips from some 15 or 20 conductor connectors in GM junkyard vehicles.
If I look around my workshop I might find some left over from the ones I mailed out.
Emery Stora
77 Kingsley
Frederick CO
>
> On Power Level system there should be a switch on the tank for the Low Air light. It has two terminals according to the schematic: a brown wire
> coming from the warning light, and a black one going to ground. A short to ground in the brown wire would of course turn on the light.
>
> Years ago it was suggested to connect the light to the compressor to indicate when it was running. Good idea, but not how GM did it, at least on my
> '75. ('76 Power Level should be same.) Assuming you have stock Power Level system, I would 1) disconnect the black wire at the switch. If light goes
> off, you probably have a shorted/stuck switch. 2)Next, disconnect the brown wire at the switch. Light should go out. If not, you probably have a
> short to ground in the wiring from the light.
>
> OTOH, if you have Electro Level system, this may not apply to you. According to the schematic, the '76 Electro Level doesn't even have a Low Air
> light, but I'm not familiar with that system, so I'll defer to Emery or others.
>
> HTH
> Rick Staples
>
> --
> Rick Staples, '75 Eleganza, Johnstown, CO
>
> "Advice is a dangerous gift, even from the Wise to the Wise, and all paths may run ill." -Tolkien
>
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