Pass-Key 3 Security Message ???

I just bought this 2004 Montana at an auction. Starts and runs good. But the Pass-Key Security Message stays on. What can I do? The dealer said they have to put it on there tester @ $69.00 /h to see what it might be. Could I reset it some how. Both keys work great. One has pk3 stamped on it. Any help would be appreciated.

I borrowed a trouble code reader that is also suppose to clear troubles. It gives me an err message. The brand name of the reader is CTOOLS . The Van is Canadain. Do I need something different or do I have bigger problems ?