2002 Silverado 1500 wont crank - turn over unless hold key in start position from 5 seconds to two minutes. after holding the key in start mode for a few seconds or a couple of minutes, it will start and run with no problem. if you turn it off and start it again quickly, it will usually crank and start right up. the time needed to hold the key in start position is totally random.

some of the things that I have tried already...
verified that all battery and starter cables are tight
verified main ground from battery and engine ground strap are tight
tapped on starter and tapped on steering column below key
left key in the on position for 15 minutes, then turned off and tried to start again. this re-sets the security system

the starter works great and the battery is less than a year old.

I am thinking that it could be the key switch assembly or the key alarm switch assembly. I just wanted to get some suggestions before I start replacing parts.

thanks in advance

 

ignition switch maybe

 

I replaced the electrical part of the key switch assembly and that did not solve the problem. A friend suggested the starter and when I whacked on it a little harder the truck would start. Replaced the starter, no more problems.