2004 C5 auto transmission not shifting into 3rd gear

by John Wayne
(Edisto Island, SC)

Car has only 40k miles, very nice condition, not hot rodded.

All has been fine, suddenly one morning when first started, it shifts from 2nd to like neutral. Also speedometer not working. Tach is working. Average speed and such indication 0 on DIC. Also related to speedometer not working. Will shift manually 1st and 2nd but 3rd is like neutral.

Trans has always been fine.speedometer and shifting are related?

SPEED Sensor in differential area is tight, harness seems fine. But still could be bad?

I figure a dealer will shaft me for a simple fix.

Thank you.

Wayne