how does one read the dtc codes?

All DTC codes prior to 1996 are OBD1 You would need a scanner that does both OBD1 and OBD11 The ford scanner connection is under the hood . I have one that does both after 1996 they became OBD11 universal to all vehicles Prior to 1996 each make of vehicle had a different connection. If you cant buy one at a parts store for ford OBD1 or one like mine that does both you might want to search e bay This is the one you need or the next link if you have an OBD11 scanner https://www.amazon.com/INNOVA-3145-Ford-Digital-Reader/dp/B000EW0KHW/ref=asc_df_B000EW0KHW/?tag=bingshoppinga-20&linkCode=df0&hvadid={creative}&hvpos={adposition}&hvnetw=o&hvrand={random}&hvpone=&hvptwo=&hvqmt=e&hvdev=c&hvdvcmdl={devicemodel}&hvlocint=&hvlocphy=&hvtargid=pla-4583795260709503&psc=1 https://www.amazon.com/Male-OBDII-Diagnostic-Adapter-Cable/dp/B01GNMKHU6/ref=pd_lpo_sbs_263_t_1?_encoding=UTF8&psc=1&refRID=530NWEJE2W3HB55377KX