Cadillac Repair: 94 sts 32v northstar cadillac, auto button, word history

Question
How do I retrieve trouble codes without scaner

Answer
1. Turn ignition key ON. Do NOT start the engine.

2. On the CLIMATE CONTROL PANEL, Simultaneously push and hold the OFF and FAN UP (^) buttons inward for 3 seconds and release them.

3. On the FUEL DATA DISPLAY you will see a combination of LETTERS & NUMBERS appear followed by the word HISTORY or CURRENT.

4. Write these down and tell me which codes are HISTORY and which are CURRENT.

5. The display will stop at PCM?

6. Push and release the AUTO button and turn OFF the ignition key.