Thanks for the brief write up. I was wondering what was involved.

 

perfect...thanks, exactly what i was wanting to know....its forever irritating not having that button work, but for some reason ive never dug into it. as soon as i get my 4wd going again (UGH) ill be looking at a new button back there

 

This thread has now answered my original question as to whether these switches are a common problem. The first time I went in there I could see that there really wasn't much protection against water intrusion. GM could have put a rubber boot over the outside of the switch that would have also served as a gasket between the switch and the hole. If I can come up with a way to do that, I'll post it up.

 

I got into the switch today, opened it up to diagnose. I had thought to find corroded terminals, but everything was clean and bright. The problem turned out to be the contact spring. Within the body of the switch are two concentric coil springs, the outer one is purely for return pressure on the pushbutton, the inner one makes the electrical contact. This inner spring was just compacted enough that it didn't reach the two contacts about 20% of the time, but my experience with the original switch, which lasted from '03 up to '10 was that the failure rate gradually increased over time to 100%. The remedy is to stretch the inner spring slightly, not too much and not at an angle, so it is a little longer. If the spring is too long, it will make constant contact; of course, you just want momentary contact.

After stretching the spring and reassembling the switch, I tested it thru several dozen cycles with a continuity tester and it didn't miss once. I do have a new switch on the way, and it will be a spare. Of course, we all know that when you have a spare part on the shelf, the installed part will never fail. Think of it as insurance.

BTW, the part number for this beast is 15760719.