Cadillac Repair: clering old computer codes, auto button, code history


Question
QUESTION: how do you clear computer code history? i have codes pc 0340 0372 0603 1323 1350 1375 1377 1520 1599 i assumming these have been old problems from past i've have had the car 2 months

ANSWER: Without trying to be RUDE, Let me guess, You have a 1931 Cadillac Roadking with the flathead 6 cylinder engine in it.

Am I close ?.

---------- FOLLOW-UP ----------

QUESTION: sorry i have a 1996 cad sedan  deville  

Answer
 

1. Bring all the codes back up and when the display stops at PCM?.

2. Keep Pushing and releasing the HI (fan up) button until you see PCM CODES CLEAR.

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

4. Wait 15 seconds and recheck for codes.