98 Jimmy 4x4 4.3 liter trans. problem

HI everyone, My 98 jimmy 4x4 4.3 liter v-8 has a problem,it does not start out in first, I pulled the codes(did not erase them)(P0740,P0785,P1860),took it to the trans. shop and it did not show any codes(ran fine also) he looked up the codes that I had and his scanner told him that most likely was an ignition switch gone bad(no other problems), I drove it home,ran fine for about 5-10 miles then it locked out fourth and first gear, and SES light came on. My question before I install the new switch is, is it likely to be the switch causing my problems? I know the 97's had alot of problems but havent heard too much about the 98's. Thanks everyone Dave (this is also posted on the "problem diagnosis" page which I think might be the wrong one? sorry)

Yup, it's the ignition switch.

I'm surprised the administrators have not made a sticky of the GM tech serv. bulletin for the s-series.

I had mine replaced 2 years ago. It just bailed on me again...

Failing causes the tranny to go into limp mode - third gear only. Fluid pressure skyrockets, and the tranny will detonate after a short while in this mode.