My 2003 cadillac cts drive shaft is makin a knocking noise how do i replace the drive shaft

Try cranking the engine with the belt removed.
You may have another pulley that is locked up.

Too big a job for an answer here. Best to buy a service manual if you want to try to do the job yourself

unblot it , unplug it and replace . then take it to the dealer so they can remarry all the other modules to the pcm .

Try the drive shaft sensor. Had a similar problem and had the drive shaft sensor replaced. It worked.

during colder weather, the oil will be somewhat sluggish until it warms up, you may want to change to a thinner viscosity oil during the colder months of the year.

I had the same noise on my wife`s 03 cts. It was the the rubber bushing on the shifting arm from the shift lever to the trans. The arm was 250.00 plus I installed myself. Very easy to get to. Bad design should not have went bad.

you bent a rod get the motor from someone other than dealer they will soak you

THIS MAY SOUND STRANGE BUT DO YOU FEEL ANY VIBRATION IN THE SEAT WHEN YOU HEAR THE HUMMING IF SO I WOULD SUSPECT THE U/JOINTS IN YOUR DRIVE SHAFT ARE GOING BAD

Try having your braking system checked, it may be a vacuum problem. I had the same problem and it was a vacuum problem...it's easy to fix.

My 2003 CTS had the same noise problem while on vacation one day. When I returned from the vacation and dropped it off at the Caddy dealership it was revealed that several of the "U" joint nuts had worked themselves loose. A quick fix was to tighten up the "U" Joint bolts and the problem was solved!