Full size truck or the S-10 series? Full size would be OBD1, but 95 1/2 S-10 could be OBDII and requires a scan tool. OBD1 will flash codes and what you need to do is read the code by counting the flashes of the 'check engine' light. Look under the dash, drivers side for a 12 pin connector. Key on and engine off - jump A to B and pay close attention to the engine light...ie: 'flash'- short pause- 'flash' 'flash' means code 12(one flash and then 2 flashes) and it should flash that code 3 times. Code 12 just means no rpm and normal.
If any fault exists after the code 12 is flashed, that number can be used to determine the fault or at least lead you to what circuit failed. Google the code or post it here and someone or myself will assist you.