A 2002 Chevrolet Silverado has many diagnostic systems running at the same time, the most commonly accessed of which are the second-generation On-Board Diagnostic system and the antilock braking system (ABS). Accessing both requires the use of a handheld code reader and the Silverado's data link connector (DLC). The Silverado features other diagnostic arrays, such as those for SRS air bags, and while it can also connect through the DLC, handheld equipment is not readily available for the general consumer.
Open the Silverado's driver-side door. Put you key into the vehicle's ignition cylinder, but leave it unturned for the moment. Look into the driver's side leg space. There, beneath the dash and the steering column, you will locate the Silverado's DLC outlet. It's made either of black or gray plastic and features 16-pin receivers. It will not be concealed behind a trim panel, and it will be out in the open for easy access.2
Connect your diagnostic handheld device to the Silverado's DLC. Most types of scanner use a length of diagnostic cable. The end of this cable features a plug with 16 pins. It will fit the DLC without any problem or need to force it into place.3
Switch on your diagnostic handheld. Turn the key in the SIlverado's ignition. This, in turn, will activate the Silverado's electrical system and central computer. Depending on the brand and type of scanner you are using, you may need to crank the Silverado's engine before the device can sync with the central computer.4
Look at your handheld's screen. If the device has not pulled OBD-II or ABS codes, the manufacturer has not preset your device for code auto retrieval. Consult your device's user's manual for instructions on how to enter a scanning command. Both OBD-II and ABS scanners function differently by brand, and operational procedures differ by device.5
Scroll through the codes once you device has retrieved them from their respective diagnostic systems. You can partially decipher OBD-II codes before looking them up. Each alphanumeric code begins with a letter designating the part of the Silverado affected. "P" stands for "power train," "B" stands for "body," "U" stands for "network connection" and "C" stands for "chassis." Some "B" codes will cover brake functionality, but not those covered by the ABS system. ABS codes are only numerical.6
Look up the meaning of each code that appears on your handheld device. Your device's manual may contain a list of coding definitions. For OBD-II scanners, this list entails the generic codes standard to all post-1996 vehicles. General Motors also has a supplemental list (see the link in the Resources section for these codes). Generally, most vehicle owner's manuals do not contain diagnostic coding references.7
Make a list of every problem currently afflicting your Chevrolet Silverado. If you choose not to fix the problems yourself, this list will save you money at the repair shop, as you will have performed the diagnostics for the mechanic; most garages charge diagnostic fees.