Cadillac Repair: 1993 Cadillac Deville diagnostics, pcm 5, digital speedometer

Question
I can't seem to find where the diagnostics hook up is on my 1993 Deville. Can someone please tell me where it is.

Answer
This vehicle has it's own built in diagnostic sytstem via the climate control panel.

1. Turn ignition switch to the ON position. Do NOT start the engine.

2. If you have a DIGITAL speedometer, Go to the climate control panel and simultaneously push and hold the OFF and WARMER (fan up) buttons for 3 seconds and then release them.

3. On the fuel data display you will see LETTERS & NUMBERS display together, These are your CODES, Followed by the word History or Current for EACH CODE that displays.

4. The display will stop at PCM ?.

5. Tell me what codes you get and which codes are History and which codes are Current.

6. push and release the AUTO button.

7. Turn ignition switch OFF.