Cadillac Repair: car codes, climate control, auto zone

Question
how can i find out if there are any erroe codes for a 99 CADDY STS IF IT WONT START? I CANR BRING IT IN TO AUTO ZONE OR ANY WHERELIKE THAT

Answer
1. Turn ignition switch ON. Do NOT try and start the engine.

2. On your climate control panel: Simultaneously push and hold the OFF and WARMER (^) buttons for 3 seconds and release them.

3. Immediately look at your fuel data display and tell me EVERYTHING, As if you were video taping it, That displays on the screen until it stops displaying.

4. Turn ignition switch off.