You are referring to vehicles that had OBD1 emissions. Your Focus has OBDII.
In days of old you could put a paper clip between upper right and lower left connections on the Comm plug, switch the engine on and the `Service Engine Light' would flash `1' then `2' (ie, 12) three times and then the fault code, then 12 three times. Not any more. With OBD II you need a code reader, try the paper clip trick on your Focus and you will have serious problems
Sorry | 
