1998 4dr 4x4 82,000 miles

I seem to have the same security no start issue as many other threads here with a few twists. It has been going on for a year or so. In the mornings I can start the Blazer with no issues, it runs well and I can drive to work. It sits outside and gets warm and if I try to start it at lunch or at the end of the day it starts for a couple of seconds and dies. The Security light then comes on and stays on (does not flash). Sometimes waiting 10 - 20 mins it resets and starts fine. I have had to leave it overnight on several occasions as it would not start after several hours.

It has been in the shop for the last 2 months with this issue. Last year I had to replace the fuel pump. This last stint in the shop we changed the ignition switch, BCM, and Passlock Sensor. We have also tried the Pro Bypass Module from NewRockies.com without any luck.

The Mechanic is not getting any useful codes when this happens. We did determine that sometimes when it fails to start if we leave the key in the on position and hit the bottom of the steering wheel a couple of times the security light in the dash will blink and we hear 2 or 3 clicks like a relay and then it will start. But this does not always work. I have also had a buddy put a code reader on it, he did not get any codes but he hit clear anyway and it started after that.

Any ideas where to hunt next are greatly appreciated.