What Can a Scan Tool Do?
Scan tools are designed to interface with a car’s onboard diagnostic system to facilitate the diagnostic process. In that way, they are similar to car code readers. They can be plugged into an OBD-I or OBD-II socket, read and clear codes, and view data readouts from various sensors. However, scan tools go beyond that basic functionality. In addition to reading and clearing codes, a scan tool may be able to:
Store and play back live dataGraph dataRead generic and manufacturer-specific trouble codesDisplay pending codesProvide trouble code definitionsProvide troubleshooting procedures or tips
Although the ability to read and clear codes is important, the additional functionality provided by a good scan tool can be helpful in diagnosing a problem. OBD-II vehicles, in particular, can provide an enormous amount of data from a variety of sensors, which is why many scanners can store and play back live data. This allows you to test drive the vehicle and then view a recording of specific sensor output readings during operation.
How to Use a Scan Tool
The exact procedure for using a scan tool varies depending on whether your vehicle has OBD-I or OBD-II. Some vehicles with OBD-I also have unique steps or procedures, and some aren’t designed to work with scan tools at all. Here are the basic steps involved in using a scan tool:
The Importance of Scan Tool Knowledge Bases
In addition to interfacing with the onboard diagnostic system of a vehicle, the other important thing a scan tool can do is provide you with some type of knowledge base. The specific information contained in the knowledge base varies from one manufacturer to another, but it’s almost impossible to overstate the importance of good troubleshooting information. Unless you have relevant prior experience with the specific problem that you’re dealing with, a good knowledge base can save you time. Scanners that include troubleshooting information and other tips typically provide you with the definition of a code, the potential faults that can lead to that code being sent, and the tests you can do to track down the cause of the problem.
Premium Scan Tool Features
The best scan tools essentially provide you with a one-stop-shop that includes code and data reading functionality, advanced knowledge bases and troubleshooting tips, and a built-in scope and other meters. Some of these tools, like the professional-grade Snap-On MODIS, are expensive, but they provide all of the tools you need to identify, test, and diagnose failed components.
Premium Scan Tool Alternatives
Although professional-grade scan tools can be prohibitively expensive, you can achieve much of the same functionality without breaking the bank. Some of the things you might want to have in your toolbox include:
A good consumer-grade scan tool or ELM327 scanner A multimeter and, if possible, scope Access to the internet
While resources on the internet don’t provide a direct 1:1 replacement for the type of troubleshooting information you get with a professional-grade scan tool, this is a more affordable way to go. A good consumer-grade scan tool (or an ELM327 scanner and the right software) will get you on the right track, and you can supplement the information that your tool provides with an online OBD-II code chart and troubleshooting information. After you’ve tracked down the likely culprit, tools like a multimeter and scope will help you determine whether or not specific components are bad.
