The Buick Rendezvous, being a GM product, uses one of the three GM passive antitheft systems. If the key is a plain metal key with no contacts on it and is not stamped "PK3" it is probably a Passlock system. In that case try the ten minute procedure in the Common Problems section of the first source, and if that allows it to start once use the thirty minute procedure to make it last. Be aware all ten minute intervals are *at least* ten minutes exactly.
If the key has a pair of contacts it is the old Passlock I/II and the contacts from the old lock cylinder are not connecting. If the key is stamped "PK3" it is the Passkey III system. You can try the procedure toward the end of the second source but I thnk it requires a working master key. Doesn't hurt to try, though.
You can buy a bypass unit that permanently houses the transponder from your key. But if you've already replaced the transmitter at the lock cylinder and the transponder in the key is good, then a bypass won't help.
You have a transponder in the key which needs coding to the car ..... changing the lock means you have lost the coding so the car will not start .... quitye a loty of mobile key locksmiths do this and it is not dear to do
No you can't there would be no point fitting it if it was easily bypassed.
i replaced the lock cylinder with a new one , now car wont start
