99 5.3L Z71 Transmission Woes

[JJLL]

A few months back I experienced an oddity with my transmission. One morning i shifted from Park to D and gave the truck some gas and it seemed like it was stuck in 3rd. I stopped and checked the fluid and it was full and clear and smelled normal. I then restarted and slipped it in gear and off I went without a problem.

 

Over the next few weeks, I noticed that when stopping at a light, it would not shift to 1st until I hit the gas to go and in the mornings, if it started in 3 again, I could just stop and restart to fix the shifting issue.

 

More recently, when in D the transmission is in 3rd. If I manually shift it to 2nd, it goes, but it will not go into 1st anymore. It acts like 2nd. When driving on the highway, I can shift to 3 from D and feel a shift, same when going to 2, but it no longer shifts automatically at all.

 

I had it checked out months ago and was told my transmission was going out and my clutches were burning up and cause it to slip soon. It doesn't slip and I have driven another 10K miles since then.

 

I find it difficult to replace something that is not completely useless.

 

Is this a programming issue or is this mechanical?

 

99 Z71 4x4 5.3L 155K

[GM-Tech]

It's not a programming issue. Programming doesn't suddenly go bad. Could be mechanical, could be electrical. Hard to say without some diagnosis.