Program new key fob for Cadillac cts 2003

There are several methods of doing this - but your 2003 requires that you either go to the dealer for them to add a FOB with special equipment (ask if they'll do it for free - can't hurt). If you have time to kill, you can do it yourself with Method 3 as described and found at:

Key Fob Reprogramming General Cadillac Forums

Method 3 - Key Fob Auto Learn


This procedure will first erase all known key fobs. The procedure will then program a single or multiple key fobs. Method 3 is a series of three 10-minute key cycles, for a total of 30 minutes. This procedure requires that you have a replacement key fob and the vehicle mechanical key.

Important: All previously programmed key fobs will be erased upon completion of the 30-minute programming procedure. The order in which the key fobs are programmed will determine its numbering position within the RCDLR memory. The first key fob programmed will be key fob #1, and the second key fob programmed will be key fob #2. The number stamped on the key fob case is for reference only: #2 can be programmed as #1.
Do not place any known good key fobs in the vicinity of the vehicle when programming with Method 3. If the RCDLR recognizes a known good key fob during Method 3 programming, the programming mode will resort to Method 1.


The vehicle must be OFF.
Place the replacement key fob in the console pocket with the buttons facing forward.
Insert the vehicle key in the driver door lock cylinder located in the driver door handle and cycle the key 5 times within 5 seconds.
The DIC will display a message: OFF/ACC TO LEARN.
Press the OFF/ACC portion of the ignition button.
The DIC will display a message: WAIT 10 MINUTES, then it will count down from 10 to 0, one minute at a time.
When the counter reaches 0, DIC will display OFF/ACC TO LEARN.
Repeat steps 5-7 two more times, for a total of 30 minutes.
The DIC will display a message: OFF/ACC TO LEARN.
Press the OFF/ACC portion of the ignition button.
A beep will occur and the DIC will display: READY FOR FOB 1. At this time all previously known key fobs have been erased. When fob 1 is programmed a beep will be heard and the DIC will display a message: READY FOR FOB 2.
Additional key fobs can be programmed by taking fob 1 out of the pocket and inserting fob 2. If desired, up to 4 fobs can be programmed. Once 4 fobs have been learned, the DIC will display a message: MAX FOBS LEARNED, and automatically exit the program mode.
If learning less than 4 key fobs, press the OFF/ACC portion of the ignition button to exit the program mode.
Operate the active portion of each key fob in order to finalize the programming sequence and verify correct system operation.

Good luck!