I bought an obd1 scanner but that didn't work as instructed, and i can't find a definitive answer after a googling. It's a 1991 sedan deville gold key. This is my first cadillac and it's got a bunch off little problems. I know i can't get help without the codes!!! Help!!!

 

Very easy! Turn your key to run (engine not running). Press and hold the OFF and Warmer buttons on your A/C Heater Control. All the segments will light up. Look over at your FDC (Fuel Data Center). Codes will be ran starting with E, then EE, then F, then FF and ending with .7.0. The E codes are engine codes (current and history) and the F codes are body.

TS

 

You need to get factory service manual - Helm inc or search net .... many times are on ebay. Diagnosis is based on using the OBD built into car not a scanner. EE & FF current codes. E & F are history or intermittent codes. Lots of info in FAQ section