How to Run a Diagnostic Test on a 1993 Chevy Truck

by Richard Ristow
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Chevrolet trucks manufactured before 1996 predate the current, standard On-Board Diagnostics (OBD)system, so owning an OBD-II scanner will not help you diagnose engine problems in a '93 Chevrolet truck. The scanner will not understand the coding and the cable will not fit into the assembly line diagnostic link connector. However, retrieving trouble codes and diagnosing a '93 Chevy truck engine is still easy. You can do the job with paper, a pen, and a paper clip.

Step 1

Locate the ASDL connector in your '93 Chevy truck. It should be on the driver's side, under the dash and near the steering column. It is made of plastic and has 12 pin-receiving slots.

Step 2

Bend a paper clip into a straight wire, then bend it into a tight "U" shape.

Step 3

Place both ends of the U-shaped paper clip into the ASDL. The paper clip has to connect the two slots on the top row of outlets. They will be on the end of the row to the far right, and the will be side by side.

Step 4

Place your key into the Chevy's ignition and turn it, but don't crank the engine.

Step 5

Watch the "check engine" light. It will start flashing. Chevy trouble codes are two digits. The first digit will be represented by a long flash. Secondary digits will be relayed through quicker flashes. For example, trouble code 16 will be relayed with one long flash and six short ones. Write the codes down as the "check engine" light sends them. You will need to find the code definitions, but you do not need to purchase a reference book. Certain websites archive older, non OBD-II trouble codes (see Resources).

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