Rear air problem

[AUHUMMER]

Originally Posted by working Hummer

But the pump does not run when the truck is off. So what's the point of pulling out the fuse?

That's the point---it IS running with the ignition off. I was worried about running down the battery and possibly burning up that damned expensive compressor.

Thanks Humtech---I hate to ask this but where is the relay and how do I check or is it just easier to go ahead and replace it and see if that works? Where might I find on of those animals?