how do I check the codes on a '93 GMC jimmy with the vortec v-6? I was told to jumpA & B in the OBD1 connecter under the steering wheel..... which one is a and which one is B? a pic would be greatly appreciated, Thanks in return, Eric

 

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look at this site for codes and how to get the code http://www.s10blazers.com/service_engine_soon.htmhope this helps this is pritty much what swartlkk said you'll see