do I need a special scan tool for check engine light I have a 93

 

you need to put a jumper wire between terminals TE1 and E1 of the diagnostic terminal connector located in the engine compartment
then turn the key to the on position
codes are usually shown in 2 digits numbers like code 24 is 2 flashes, a pause and 4 flashes
a pause of 2.5 seconds will follow the next code, when all codes are transmitted the entire code will be flashed again after 4.5 seconds.