98 Jimmy transmission 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

When the tranny goe sin third and stays there, its in limp mode. If your tranny is shifting gears properly when theres no SES light, then chances are its not your tranny thats the problem. This could be a ignition switch problem. It could be a security system problem. There have been issues with aftermarket security systems that do exactly what your deescribing. The secuity system inturupts power to the transmission and causes the tranny to go into limp mode. Either way, it sounds like the tranny is losing power and you have to trace where its losing it from.

Good Luck!