Check Engine Codes

I have a 1992 GMC Safari V6 and the check engine light is on. Is there a way to check the codes without a code reader? I know on my 1997 Dodge Ram all I have to do is turn the key on off on off on and the check engine light will blink in sequences. Is there a similiar procedure for the safari?

If I remember correctly, with the igntion off you install a jumper between pins A+B at the diagnostic port, then turn the ignition on and count how many times the light flashes