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Code Reader

Electronics: The Rx For Your Late-Model Corvette

Andrew Bolig Sep 1, 2000

Step By Step

The over-the-counter code readers are typically paired with a book listing each numerical code and what they stand for. There are code readers for every price range and ability. They all hook up using the Diagnostic Link.

It’s found under the dash by the driver’s right knee, and should have a little black cover with the words “Diagnostic Link” on the front. Once the cover is removed you can see the contacts inside the connector. Receiving information from the computer can be as easy as crossing two of these contacts together with a paper clip, or an open-ended connector or a specially designed “Key” as shown.

If you feel a certain amount of hesitation about just crossing wires in the connector and would like something a little more foolproof, you can get a diagnostic grounding plug.

It will install only one way, and there are different grounding plugs to initiate different tests. These will all show codes by flashing the Service Engine Soon light a certain number of times for each particular code.

Always remember to turn the key on first, and then insert the diagnostic tool. Remove the tool before turning off the key.

When using a code reader that just shorts the terminals together, you are limited as to the information that’s available. They will give you an idea of where the problem is, but you’ve just touched the surface of what’s available to you. The next step up in code readers is a device like the AutoXray. These types of readers provide you with any errant codes, along with actual data from the various sensors. This can narrow down a trouble area. With this type of code reader, the problem code is mentioned in English instead of a numerical code. The AutoXray scanner will run a couple hundred dollars—money well spent if it saves you a trip or two to the shop. Even if your Corvette does go to the shop, knowing where the problem lies provides you some form of insurance against the size of the bill.

Scanners such as the AutoXray will benefit the home mechanic by shortening the time it takes to find the problem. If you feel a little more adventurous and don’t mind adding another zero to the price of the AutoXray, the Vetronix Tech 1A may be the code reader you need.

This is the code reader that GM used until 1994. You can access computer areas that other code readers can’t, and you can get readings at real time, as they occur. Another benefit of the Vetronix Tech 1A is that it will do a diagnostic circuit test, scanning the entire system including the circuitry. With this code reader you can also make checks and changes to identify that systems are operating properly. This reader definitely gives the home mechanic all of the information he needs, and more.

The electronic systems in today’s Corvettes are simply staggering. Computers regulate the engine systems, handle chassis functions, and just about everything else your Corvette does. It’s easy to see why electronic systems have baffled backyard mechanics for so long. Before electronics, if there was a problem it was obvious to one of the senses. You could hear, feel, see, or smell the problem area. With an electronic system, a faulty part could be overlooked because there’s no difference in appearance or obvious proof of an improperly working part. Without some form of input, a faulty part could result in playing a game of remove-and-replace until the bad piece could be located.

Thankfully for us, GM has made the diagnosis process quite simple. The key to unlocking the once-obscure realm of engine analysis is a code reader. If there is a problem with a part or operating system, the computer will show that there’s a problem by lighting up the “Service Engine Soon” light on the dash. It will also identify the problem by giving it a numerical identification.

We wanted to learn more about using these code readers, so we went to Chris Petris of the Corvette Clinic to get the full scoop.

In an upcoming issue, Corvette Fever will use these various code readers to gather information about what’s going on under the hood of some of the Corvettes around the shop.

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