Guest Blog: Diagnostic pre- and post-scan reports are solid gold for profitability

Dec. 5, 2023
Keith Wray from Snap-on shares how performing pre- and post-scans not only finds additional work needed but reduces comebacks as well.

To understand where we are, we must always understand where we have been. 

The first computer-controlled system on a vehicle had to perform only one function, to control the electronic fuel injection. This was back in the day when the 1968 Volkswagen Type 3 Fastback had a transistorized electronic module manufactured by Bosch and was the world’s first mass produced car to have electronic fuel injection.

In the mid-70s, citizen band radios (CBs) were cool.

I installed a CB radio under the dash of my 1974 bright yellow Mercury Monterey. I was all in, talking to truckers on their way to work every day and letting them know what was going on to keep their big rigs moving down the highway. 

As we conversed, I learned an insider secret I am quite sure was held for only those driving the rigs and maybe a few select individuals. I have kept this secret until this very moment.

I cannot divulge the CB channel, only because I cannot remember, but if a trucker passed a Volkswagen Fastback in those days, all they had to do was to “key the mic,” also known as holding the button down on that channel. The transistorized electronic module on the VW would freak out at the frequency signal and would cease to deliver any fuel at all through the injectors. Yes, it died as if you turned the key off in the ignition. The vehicle would sit on the shoulder of the highway, unable to restart, until the trucker would let go of the mic button or drive out of range of the radio frequency. Of course, a shielded wiring harness kit would correct the problem for the Volkswagen owner. What a great example of the early years of radio frequency interface (RFI).  

In the late 1970s, my time at a Datsun dealership taught me to check a few basic things before dragging out the cumbersome factory tools to check the computer system that controlled the electronic fuel injection system. Somewhat like a pre-scan, I’d look at things that would affect the computer system and/or the components. You’d want a good, clean battery connection, for one. There’s nothing like a poor ground or low voltage to the computer module to wreak havoc with the system. Dirty voltage due to alternator diode is another good example of what we might have pre-scanned. I always did a vacuum test to see the mechanical condition of the engine and an exhaust flow analysis. 

Through the ‘80s and ‘90s, it was always a great idea to check some basics prior to a scan test. If you didn’t, you could go down the wrong path and waste a lot of time.

As more and more modules were added, and technology grew by leaps and bounds, the systems began to be able to detect issues of those basic items. Then the original equipment manufacturers (OEM) began to network the modules together. That allowed our developers to run a scan test for codes of all modules, in a couple of minutes. 

Now, it’s called pre-scan or post-scan; pre-repair and after-repair. This feature came along in 2014.

I have always believed that comebacks happen because of something we missed, more often than a mistake we made. The most profitable technicians and shops out there perform a pre-scan on every vehicle that comes through the door and a post-scan is the last task before the keys are handed back over to the customer. This practice finds additional work needed and reduces comebacks and it is a big timesaver as well. 

Many insurance companies require a pre- and post-scan to cover the work. This better ensures that the work was done correctly and that nothing else should have been taken care of. 

The diagnostic health scan option on Snap-on scan tools is a great option to provide your customer with an easy-to-understand overview. This customer-friendly report can be printed out for the customer before the repair as well as after.

Performing a health check will give you and your customer peace of mind. Many of the systems scanned do not turn on a light or warn the driver, so this health scan will uncover these unseen issues.
The printout of the diagnostic health scan report creates a level of professionalism that greatly adds to the credibility of the shop and its technicians. It also goes a long way to justify the diagnostic charge. 

In fact, shop owners, when is the last time you adjusted that charge? That charge became an industry standard over the years to cover the investment of the information and equipment to properly diagnose today’s vehicles. 

Back to the printout, show your work – show your worth. 

Along with the ability to be printed, these reports can be emailed or texted to the vehicle owner. This is possible using Snap-on Cloud, found at Accounts are complimentary for diagnostic tool owners with current software.

The report goes to the cloud when the scan is complete and from there, it can be easily accessed by phone, laptop, or desktop. Once received, it can be added to the customer’s file, emailed, or texted to them.  

Another time-saving feature of the pre-scan is that if a code is detected, it will display a button with the word, “diagnose, " which will take you straight to the Fast-Track Intelligent Diagnostics landing page. In the images below, we're using an OBD-II scanner, the ZEUS+, also equipped with our exclusive Fast-Track Intelligent Diagnostics.

Touch the button and you now have access to a workflow to find the problem in the fastest manner, all on one page. Fast-Track Intelligent Diagnostics links problems with solutions. Instead of looking at hundreds of lines of data, TSBs, repair tips, and functional tests, everything is specific to the vehicle and the code, all from the touch of a button after the pre-scan.

 The overall workflow now using pre- and post-scan looks like this:

Other scan tool companies offer a similar feature to the Snap-on pre- and post-scan, and they label it as topology. 

Since the topology of other scan tool companies is a generic template, it is impossible to describe the vastly different layouts and designs, much less the completely different data bus configurations from one OEM to another. 

We decided that with the complexity of today’s vehicles and their systems, we would keep it simple, efficient and fast. The pre- and post-scan layouts are quick and precise with a button to get you to the problem fast. The diagnostic health scan is for customers to understand and appreciate.  

Snap-on pre- and post-scans are VIN specific. That means there won’t be any modules listed that are not present on the car. We only provide data that is relevant to the specific vehicle. 

Technology has made these days the good ‘ole days. We have come a long way since CBs and VW Fastbacks. 

Sponsored Recommendations

IA900WA Single System & Workflow: Wheel Alignment & ADAS Calibration

Sign in. Your browser can't play this video.. Learn more. 0:00 / 39:04. IA900WA Single System & Workflow: Wheel Alignment & ADAS Calibration | Autel. 50.6…

Voice Your Opinion!

To join the conversation, and become an exclusive member of Vehicle Service Pros, create an account today!