Can I run a code test on a 1991 chevy s10 2.8l with a paper clip, if so how?

Jump A to B and turn the key to the run position.
Make note of the "ears" on the connector as view looking directly on.
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Attachment 27431
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Once the sequence begins, you will see first one flash, then two, three times, OK? Then the fault sequence will begin. If left alone, that code will also flash three times before moving on to the next code, if any, or it will flash one, flash two and repeat as long as the key is ON or the fault is no longer present.
Let us know what you get.