Computer Diagnostic

ColchinStill006Vehicle Computer Diagnosis Simplified and Explained

“Computer Diagnosis” is sometimes misunderstood. It is my goal to put you at ease with this term and the whole diagnostic experience.

It’s no surprise that computers control and monitor just about every aspect of motor vehicles, so with that knowledge there are different reactions from different people, including auto repair professionals;

  • Some expect the computer to “tell” them what’s wrong with their car.
  • Some expect some sort of magic to happen when a scan tool is connected to their vehicle computer.
  • Some are absolutely scared to death of the whole process of diagnosing vehicle problems.
  • Some use “Computer Diagnosis” to make the diagnostic process look mystical.

Computer Diagnostics involves a device that is capable of communicating with your vehicle computers via a port called the Diagnostic Link Connector (DLC). This diagnostic device is commonly called a scan tool and as you might imagine there are many brands all with varying capabilities. The simplest of scan tools are nothing more than a code reader. When your car is experiencing problems or a Check Engine Light our first step is to scan your car’s computer memory for stored Diagnostic Trouble Codes (DTC).

The Myth About “Codes”

Many people have a misconception that Diagnostic Trouble Codes will tell you exactly what to fix or replace on your car. This is simply not the case. DTCs do however tell us the following;

  • A sensor or circuit is experiencing a fault.
  • What “area” or system is experiencing trouble.
  • Certain operating conditions have occurred that are not acceptable to the computer program and it can no longer control those conditions.

In English, when your car’s computer can no longer control its systems, codes set to help us begin our search for the root cause. Just imagine what it would be like to diagnose vehicle problems if there were no codes – We’d be searching for the proverbial “needle in the haystack”. Simply put codes narrow the search area significantly. By the way, there are cases where a vehicle will have issues with or without setting a check engine light and no codes will be set in the vehicle computer memory (see below).

Please understand that “getting” or “pulling” codes form a computer is just that – it’s numbered codes with a verbal description. Pulling codes is by no means a diagnosis. Once codes are obtained, pointed testing begins with the goal of Root Cause Analysis (RCA). RCA is another great description for “diagnostics”.

No-Code Diagnostics

It’s important for you to know there are cases where the check engine light will turn on and set no codes in its memory. We’ve also seen cases where there is a noticeable problem with vehicle performance and no codes will set. While it is rare to have no codes to assist with a diagnostic process, it’s possible you may be faced with this one day. This phenomenon of no codes is not isolated to only the engine computer, Anti-lock brakes, transmission computers and others can experience problems while setting no codes in memory.

This scenario is a game-changer for sure simply because there are so many possibilities for the root cause of the problem. That said this type of diagnostic is very manageable. At Colchin, decades of experience, our access to automotive data bases and our people will get the job done. As always you’ll be in the driver’s seat when it comes to spending your hard-earned money.

Multiple Code Diagnostics

Many vehicles come in with more than one code stored in its computer. Most of the time multiple stored codes are related to each other – this is helpful to us because it’s more information. However when there are multiple un-related stored codes this usually presents a whole different set of circumstances and the reason is that each code or “set” of un-related codes is its own separate problem requiring a separate diagnostic to smoke out the root cause.

Once we’ve completed testing and research we’ll call you with the diagnosis, appropriate repairs needed to fix the problem and the estimate associated with those repairs.


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