on my 2002 trailblazer the cruz control stops working and the trany shifts hard first to second

harsh 1-2 upshift. cruise drops out or shuts off. is this also a late upshift?

You are not using criuse during a 1-2 upshift, they may be two problems or, they could share a speed sensor. What codes are stored? maintenance up to date ? 13 years old, how many miles? you can start with system prechecks inspecting sensors and harness to the trans, the fluid level, signs of anything to note. tell of warning light issues and transfercase gear its in?

Test the TPS and see if anything is outta normal with tuneup and sensors around there, prechecks for that too. But what results so far with codes. use a/c delco parts so you arent installing new problems.

There are no no codes stored I get up to 65 and then set the cruise control it ride good for a little while and then shuts off and all the maintenance is up to date on the car

The transmission works perfect until the cruise control shuts off then when I slow down and speed back up that's when it starts shifting hard

Yes it's just a little late also

These systems can have a component amp or synchronizer type buffer device malfunction or wiring damage, but knowing you do not have a speed sensor issue first is needed. unsure if this model uses same part. after inspections complete, the testing can be done to see mV signal is in range and verify how many speed sensors are in use. Googling Y.M.M. and symptoms might give some reading to you to be familiar, then see sites explaining sensor tests and buffer prechecks and more. the research will take some time. if you plan to go see Mr. Goodwrench anyway ?........or maybe you want to read and try some things.

Allright, no code, need prechecks, locate and number speed sensors, test mV signals for each, and TPS sweep check (basic tests of a potentiometer) It is noteworthy that internally, thats a pretty popular trans whenit comes to customers discussing its satisfaction index, I certainly hope you find the cause and refrain from letting it continue to act harsh. You can let them try and correlate the two problems, but the site I read about harsh 1-2 was discussing cruise on or off. Hope you demonstrate what it does to someone before leaving it with them. that ends up being effective...that it acts up. You could test those sensors with a good quality DVOM. and when inspecting harness? be sure the wires are not close to the exhaust or getting baked. TTFN.

After some reading about how trans and cruise speed signals were evolving, i must ask, did you run enhanced codes? The 2002 model is much newer and its TCM can have the data The same scan tool with some toggling can read other processors in the same vehicle.