New vette owner here (89coupe). I'm not sure this is the right forum for this question but here goes anyway. What does throwing codes mean? My dash says to "service engine soon" so is there a way for my dash to "throw me a code" so I might have a clue as to wha t needs to be addressed? If so, what do I need to do and where can I find what the codes mean? Sorry to be such a luddite (sp?) but I can barely use this @%&* computor.

Thanks, Kim

 

Welcome! You are correct that the "SES" lamp is telling you there is a code or codes stored. Take the time to become comfortable using the Advanced Search function of the forum. With it, searching C4 Tech, General & Scan & Tune forums you can locate which ALDL pins to jump to retrieve those stored codes using only a paper clip.
A little more searching in the same forums will give you a list of what the codes indicate but without a Factory Service Manual (FSM) you will waste a lot of money replacing parts unnecessarily.
The codes are an indication of the circuit involved, they DO NOT indicate the sensor associated with that circuit is bad, the problem could be wiring, or a vacuum hose for example rather than the sensor itself. The FSM provides the step by step trouble shooting procedure required to find the root problem.
Patiently haunting E-bay can be rewarded by finding a bargain on the FSM but even if you must purchase them new, it will be money well spent and can save many times the initial cost of the books.
You have already found a valuable resource here to maintain your Vette, there are many good people willing to help, best of luck.

 

Try here, you have a 5.7 L VIN 8:

http://www.troublecodes.net/GM/

 

Understanding the ALDL
This document covers most GM (General Motors) vehicles including the following:

GMC Chevrolet Buick Pontiac & Oldsmobile vehicles including: Astro, Typhoon, Syclone, S-10 truck, Blazer, S-10 Blazer; Camaro, Monte Carlo, Fiero, Firebird, Grand Am and other passenger class vehicles typically from 1983 to 1992 using OBD1 ECM (Engine Control Module).
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The ALDL (Assembly Line Data Link) is located on the underside of the dash of your vehicle, just to the side of the steering column. It enables you to "pull codes" whenever your "CHECK ENGINE" light begins to flash.
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These codes alert you to certain engine components that are detecting a problem, such as, EST codes, low voltage to certain sensors, and high voltage to certain sensors (amongst many).
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To check codes and view data from the ALDL you can use a Scantool, Diacom, Datamaster, or other data viewing software, but all you really need is a paperclip. Pretty cheap, huh? Here's how to use the ALDL.
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A - Ground
B - Diagnostic Terminal
F - Torque Converter Clutch
G - Fuel Pump
H - Brake Sense Speed Input
M - Serial Data (Do Not Use)
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Now, with the Key off Engine off, take a paperclip (or code scanner) and jumper ports A & B. This will read the engine diagnostic codes. Turn the ignition on, but not the engine. The check engine light should begin showing some activity. Now, this is where you have to do some paying attention and writing. The check engine light will flash in numbered sequences to reveal the codes stored by the ECM. Here's how to decipher them:
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STEP 1 - The check engine light will flash a code 12 (1 flash....pause....2 flashes = 12) three times to let you know that you are in diagnostic testing.

STEP 2 - After the code 12 flashes three times, the check engine light will begin flashing engine codes three times if any are present. Pay close attention, so as not to miss the pauses.

STEP 3 - When all the codes have flashed, the code 12 will cycle three more times to let you know that it is through. You may then turn off the ignition and remove the paperclip.