Chevy silverado auto transmission problem?

[brandan h]

2003 Chev 1500, 100k miles. 2 days ago traveling 50mph I went to passing gear on the highway but after a few seconds the truck dropped to 2nd gear. Now I am unable to shift auto nor mannually into 3ed or 4th. P, R, N, 1-2 gears all fine. When I attempt to go over 35mph the engine will rev but not upshift to 3ed gear. 2ed to 1st and 1st to 2ed are fine. Could it just be the shift solnoids or PCM? No check engine light. I don't have the money for a rebuild. Please help!
Fluid dosn't look too bad. Changed 30k ago. I droped the pan and didn't find any chucks. Mag had some paste but no spikes

 

[pedro7of9]

1 is engine tuned? miss fire can confuse computer
2 get check at tranny shop
3 doubt computer is bad with no code
4 chevy trannys go early...my buddys 2000 silverado went at 110,000 it was a work truck] but my 99 s 10 4x4 went at 95K,,,the OD lockup jumped in and out....1500 dollars

 

[gary o]

check engine light may not come on if not air pollution related. May have to have some tests run on transmission at a transmission specialty shop. Get a written estimate to repair first then decide what to do. Have you checked fluid level; hot trans. on level ground with trans. in park and engine running?