Scan tool operation

Basic scan tool operation for pulling check engine light codes is a simple procedure on OBD two vehicles.

After reading this short page you will be ready to use a automotive scan tool to perform your own basic diagnostics and zero in on the problem that your vehicle is experiencing. But first, how do you know that you have a problem.

The malfunction indicator lamp, better known as the service engine soon light comes on normally for a few seconds when the key is turned on.

And also during engine cranking but this light should go off when the engine starts. The check engine light should not come back on unless the computer finds a problem.

This quick self diagnostic test will happen every time you turn the key to the on position. When the light stays illuminated this indicates a failure and you should have a trouble code stored in memory.

Scan tool operation a quick sidebar: If you have a constant engine light illuminated, and you do not find a trouble code stored or if you receive a message that says, no communication with the computer.

Then in most cases, this indicates a problem with either the power to the computer or a ground malfunction. The electronic control module has its own separate power and ground that are usually very reliable.

But if you do get this no communication message you do want to check the ECM fuse, and also the main system grounds for opens or corrosion.

Scan tool operation basics

1) Always follow the directions in the manual supplied with the car code reader or diagnostic tool.

2) Do not connect or disconnect any connectors or components with the ignition switch in the on position.

3) Is to never short across or ground any terminals in the electronic system unless a diagnostic chart or a repair diagram specifically recommends it.

4) If the computer system connectors are to be opened for testing make sure to turn off the ignition and disconnect your scanner before you carry out these operations to avoid voltage spike problems.

Most OBD scanners extract generic codes and interface with the vehicle's computer automatically. Some older testers will ask for you to input some data before it will scan the vehicle.

Scan tool snapshot testing

Many auto scan tools like the Actron 9180 have a snapshot mode so that do-it-yourself car mechanics can operate the vehicle and store a variety of information on the fly.

When a problem occurs, the auto mechanic can drive the vehicle back home and then review the captured sensor data and voltage readings in the testers memory.

During the playback of the scan tool data that technician watches closely for a momentary change in the sensors readings, which indicates a defective component or even the wiring to a sensor.

This action is similar to taking a series of snapshots with a camera and then reviewing the pictures later. Snapshots may be taken on most vehicles with a data line from the computer to the data Link connector.

And this certainly includes all vehicles from 1996 model year and up that have the OBD II diagnostics system.

Scan tool operation again is very simple and will supply you quickly with diagnostic trouble codes that point to a malfunction in a particular system.

This narrows down the diagnosis for the auto repair shop or even for people attempting to do their own repairs. In most cases, these codes are easily diagnosed with a good automotive scanner in conjunction with a quality car repair manual.

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