Hey guys and gals, slight issue that's very confusing to me. I have an 06 LT and I had my alternator go out on me this weekend, complete cluster leading up to it but that's on another alternator relAted thread. So I replaced my alternator tonight, which contrary to what a couple YouTube videos say, it is not necessary to remove the engine mount. Anyways, it started right up and held a solid charge with everything I could think of that pulled juice on with no issue. When I jumped in to take it for a test drive, I went from Park to Drive and the tranny made a nasty thump sound and jerked. I drove it around for a bit and the rough shifting seemed to get better the more I drove. I got home, put it in Park, went back to Drive and the thumping and jerking happened again!could this just be the computer rebooting and getting all the vacuum sensors back in tune or am I looking at a serious issue here? Never had issue with the tranny before replacing the alternator and can't say I touched anything regarding the tranny while replacing the alternator! I'm banging my head against the wall here folks! Any thoughts, ideas, opinions, words of wisdom will br greatly appreciated! Thanks in advance for your help

 

Are there any warning lights on? Traction control? Check engine Light?

 

Nothing. Everything is running great according to the dash

 

Sounds an awful lot like a transmission and/or motor mount.

 

This car will be the end of me!!!! So I get in this morning to go to work, really hesitant on even driving it because of how bad it thumped last night, got in turned the key, started right up and when I shifted from Park to Drive..................................SMOOTH AS BUTTER! Running great and shifting beaurifully!!! Unbelievable and laughable! Thanks guys!

 

That is crazy!!! Well, if it comes back, throw an OBDII code reader on it and see if any codes are sitting there, even if the CEL does not light up.

Maybe do a double check on all electrical connections in the area you were working in, in case something got bumped etc..

Crossing our fingers for you.

 

A lot of the relevant codes do not illuminate the CEL until 2 consecutive instances, until then it will be "pending".

 

Check the Trans. Control Harness at the top of the tranny case to see if it's fully engaged.. See if it didn't get bumped during the repair or an oil change.
It's on the left side of the engine by the oil filter cavity and can cause a lot of problems like you described, but you never know.

Clare