Almost every system on today’s vehicles requires the use of a scan tool for diagnostics or reprogramming. Which leads to a common question: “What scan tool should I buy?” The best answer usually isn’t what you might hope: All of them.
Since purchasing every OEM scan tool would be cost prohibitive for most, and return on investment would be poor for some tools in some markets, let’s explore some options. First, there are three general types of scan tools: generic (or global), aftermarket enhanced, and OEM (or factory.)
A generic scan tool meets the requirements spelled out in the SAE documents pertaining to OBD-II that were introduced for the model year 1996. These documents require manufacturers to use one of a small list of communication protocols and be able to read and clear DTCs, view live data, view freeze-frame information, and more.
This standard enabled some manufacturers to create some very inexpensive scan tools, such as a handheld device that may be less than $100, a PC-based software application that may run a few hundred dollars, or even a cell phone app that connects via Bluetooth to a $5 adapter, plugged into the data link connector (DLC).
The major disadvantage of a generic scan tool is that they only communicate with emissions-related controllers. This means access to vehicle information is usually only going to come from the PCM and TCM. None of the vehicle’s other modules will be able to communicate with the tool.
In addition, the information in the data stream is usually limited to the basics, which are spelled out in the SAE documents. More advanced diagnostics may require viewing a data PID that doesn’t show up on a generic tool.
Aftermarket enhanced scan tools are probably the units most technicians are familiar with. Aftermarket scan tool companies write software to access additional systems and perform additional tasks beyond the capabilities of generic tools. This software is often called “enhanced.” The companies, such as Snap-on, OTC, and others, try to get as close as they can to the manufacturer’s coverage.
Although some are relatively successful, there will always be holes in aftermarket tool coverage. Also, one particular tool may work quite well with an Asian vehicle and poorly on a domestic, while the situation may be reversed on another tool. These tools can be handheld or PC-based, often work on pre-OBD-II vehicles (with additional adapters), and usually incorporate generic scan tool options (figure 1).
The overall advantages usually outweigh the disadvantages for many of these tools. Better coverage and more functionality are the main pros, while high cost is often a con.
Additional disadvantages are the time lag in coverage for new vehicles, and you’ll need to purchase updates to stay current. For example, one of these tools, completely up to date, probably wouldn’t be able to pull off a radar cruise control calibration on a very late model vehicle. And most of them don’t perform any immobilizer functions.
The price of these aftermarket enhanced tools varies greatly. For example, the VCDS by Ross-Tech does an extremely good job on Volkswagen and Audi products, and is available for around $400.
On the other end of the spectrum, you could spend more than $10,000 for a tool like the Snap-on Verus, which has pretty good coverage on a wide variety of vehicles. Of course, there are many other tools with prices that fall everywhere in between.
When choosing one of these tools, consider the makes of vehicles you see most often, and determine which tool has the best coverage for those vehicles.
OEM, or Original Equipment Manufacturer scan tools are the best option when it comes to coverage. An OEM tool will be able to perform all of the functions on the vehicles it was designed for. These are the tools the dealerships use, which makes sense, but there are independent repair facilities that have them, too.
There are still a few handheld units available (figure 2), but the majority of OEM tools are now PC based (figure 3). This means you’ll need to purchase an interface, a subscription, and install software. Each manufacturer will require different software and interfaces.
A great place to start searching for this information is www.NASTF.org. You can find what you’re looking for by clicking any of these tabs: OEM Service Websites, OEM Reprogramming Info, OEM Subscription Prices, or OEM Scan Tool Center.
The advantages of OEM tools are that you’ll have complete scan tool coverage, all programming functions, and (in most cases) immobilizer functions. Some immobilizer functions may require an LSID, or Lock Smith Identification. The disadvantage of OEM equipment will usually be the price.
Beware of clones! Clones of some OEM scan tools are readily available on the internet. These devices aren’t original and will have no support. They usually have a much smaller price tag and ship from another country. They usually seem to function as a scan tool, as long as they don’t crash.
Never trust a clone scan tool for reprogramming functions. The right way… the legal way… is to buy a legitimate tool from a reputable supplier.
SAE J2534, and its subsequent revisions, identifies the requirements for programming modules that use an aftermarket interface. There are many disadvantages to J2534. First, the documents only require that manufacturers provide reprogramming for emissions-related controllers, starting with the 2004 model year. This means that PCMs and TCMs are about all that are required.
In addition, some manufacturers won’t allow J2534 programming on vehicles older than 2004. They can provide programming for earlier vehicles if they like. For example, General Motors allows programming for almost all modules as far back as the 1996 model year.
Another example is Chrysler, which allows reprogramming coverage back to the 1996 model year, but only on PCMs and TCMs. The point is that each manufacturer is different.
Second, some manufacturers have issues with their J2534 software, such as speed, reliability, and compatibility. For example, a 2007 Nissan Quest PCM reprogram will take seven hours to perform J2534 reprogramming, but is much quicker if you’re using the OEM tooling.
Also, any errors during reprogramming could damage the module and turn it into an expensive paperweight.
J2534 Scan Tool
Toyota was one of the first manufacturers to allow OEM-level scan tool functions using a J2534 interface. Other manufacturers have followed suit, which offers affordable access to OEM level tooling.
Basically, you use a J2534 interface with OEM software and a subscription. Some of these manufacturers include General Motors, Honda, Toyota, BMW, VW/Audi, and more. But there are manufacturers that don’t: Ford, Mazda and Chrysler.
Because of the speed of change in this area, you’ll need to check with each manufacturer to see if J2534 tooling is available, because the specifics could be different tomorrow.
Some PC-based scan tools don’t like to live together on the same computer. Sometimes they share files that can conflict with each other if installed on the same machine. For example, the Ford IDS won’t coexist on the same machine with the Mazda IDS. In this case, neither tool will work correctly.
The solution? You’ll need to acquire more PCs.
Scan Tool Summary
There are a few answers to the question, “What scan tool should I buy?” One choice would be to buy all the OEM scan tools and you will have everything you need. But this is expensive and out of the reach of most repair facilities.
Another possibility would be to purchase a good, enhanced scan tool, such as a Snap-on product or a similar one from another manufacturer.
Don’t be afraid to spend the money because it will probably be your workhorse.
In addition, buy another enhanced scan tool made by another manufacturer that has different coverage. Autel makes some tools that are relatively affordable and fill holes that other tools leave open.
After you have two tools in your box, start to analyze your market and determine if an OEM tool would be cost-effective for your shop. This step may include the purchase of a J2534-compliant device, which will allow you to accomplish some programming tasks and take advantage of manufacturers that allow you to use their service with the device.
Don’t buy a Mercedes Benz Xentry for over $25,000 if you only work on two Mercedes Benz vehicles a year. But ten Fords a week might justify the purchase of an IDS. The correct answer depends on your market situation.
Do you have any engine or electrical diagnostic issues you’d like to see addressed? Let Scott know. Send him an email at email@example.com and you just may have your question covered in an issue of GEARS Magazine.