There are a lot of misconceptions going around about what Automotive diagnostics really are. I hope this article will help you understand what happens during a diagnosis of any computer or electrical related component.
When a light comes on in your dash no matter what it is you should have it checked by a professional that is ASE certified for electronics, engine performance, and L1 advanced level specialist. This will assure you that this person has taken the time to prove themselves through testing.
Once you get your vehicle to the repair facility or have me come to you, Your vehicle gets hooked up to what is called a scan tool or a code reader to see what code is set. This "code" tells the technician what system or what part of a system is experiencing a problem. Then they should study the recorded data stored in the cars computer to see when it happened and what you were doing when it happened.( ie... vehicle speed, engine load, fuel trims, etc...) Then take that code and look it up in an information data base. They should be looking for what is called a Technical Service Bulletin. If there is a TSB found they must follow it step by step before doing anything else. A lot of times the TSB is for software updates for the particular computer that is running the system. You MUST update the software before doing any other repairs. Sometimes a vehicle not working properly is because of a software glitch and once reprogrammed it works like new again. After the update is finished they must clear the code and drive the vehicle the way the recorded data said it happened the first time. If the light comes back on or there was no TSB for the vehicle in the first place. They look in the data base for the diagnostic chart made for the particular code set. The chart is information on what circuits, computers, or components to test and exactly how to do the tests. Once the chart has been completed and the problem fixed. You must clear the code again and the vehicle must be driven the way it was to set the code the first time. This will verify the repair was successful. Some times these charts take hours to get through because of the location of some of the parts needing to be tested. This is one of the reasons diagnostics can be so expensive.
Here is a breakdown of expenses your garage or myself have to properly diagnose and fix your car.
- Diagnostic scan tools run from hundreds to thousands of dollars. I own Factory scan tools which means one for each manufacturer. They run from $2000.00 to $8000.00 each. Most independent repair facilities own a universal scan tool which run from $2000.00 to $8000.00 this type of tool works for all vehicle manufacturers but is limited to what it can do, unlike the factory tools.
- Technical data bases can run $100 to upwards of $300 a month. These too come universal or Factory. I will say for TSB look ups I always use the factory data base because they update this info quicker than universal data bases, but for diagnostic charts I use universal data bases because they buy the information from the factory.
- Yearly updates for the scan tools run about $300.00 to $1000.00 each.
- Technicians yearly salary that can run all this stuff $50,000.00 plus.
So the next time you ask for a diagnostic for free or you see someone offering free diagnostics beware of what you actually get for free!!!