Cadillac Repair: 1996 Sedan deville, climate control, word history

Question
My sedan deville's service ignition light has een on for about a week when I saw the light come on I changed the spark plugs and wires hoping that that would be the source of the problem but the light is still on. Could you please give me some advice on what might be the problem?

Answer
Perfor this procedure using the buttons on your climate control panel and the FAULT CODES will appear on your fuel data display.

1. Ignition switch ON. Engine OFF.

2. Simultaneously push and hold the OFF and WARMER (^)(fan up) buttons on the climate control panel for 3 seconds and release them.

3. CODES will appear in the fuel data display in the form of LETTERS & NUMBERS and with each code that displays you will see the word HISTORY or CURRENT.

4. Tell me EXACTLY what displays in the EXACT order in which the codes display as if you were video taping the display.

5. The display will stop at PCM?

6. Turn OFF ignition switch.