I have an '06 Megacab with a blower motor that has died, slowly, over time. Over a year ago it would start and stop occasionally, but a couple weeks ago it died entirely. A friend of mine thinks the brushes have gone bad (right at 95000 miles on the truck), but I have seen some people on here with ignition switch problems that seem to have similar problems. How do you diagnose the switch? All the wires from the control switch on the dash to the motor are tight and seem good.

 

I would test the wires at the blower motor first. A test light preferably...