GMC Troubleshooting Questions? Ask a Mechanic for Answers
First, check the power steering fluid level. Is it possible that it may have leaked out while the truck was sitting?
Second, if the fluid looks ok, start the engine and then remove the power steering cap to see if it looks like the fluid is circulating in the reservoir. I've seen these power steering pumps fracture the pump shaft off because of tarnish buildup in the pump if they sit for long enough.
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