Cadillac Repair: 1994 Cadillac Sedan Deville 4.9 engine, cadillac sedan deville, dash panel

Question
The vehicle idles rough especially when cold I changed the air intake valve but it still idles rough. Where do I hook up the machine that reveals amd identifies the codes.  

Answer
Remove the big black plastic under the dash panel and you will see a small black square connector that the cable to the tester hooks up to.

OR

1. Turn ON the ignition. Engine OFF.

2. Simultaneously push and hold the OFF and WARMER (^) buttons on the climate control panel for 3 seconds and release them and CODES will start to appear.

3. let me know what the codes are.



What is the cars problem ?