Tool Q&A: Should you get involved with reflashing?

Q: What should I look for when shopping for J2534 equipment?

A: First, you need the J-Box itself. They all cost around the same, so what you should be interested in is whether the piece of equipment is approved by the OEM. You can look this up at by looking at the “Reprogramming Information” section on the left side of the page. The National Automotive Service Task Force (NASTF) makes all this information on every OEM readily available in one place.

Second, you’ll need a battery maintainer. You need a good, low-AC ripple flow of high amperage during a reflash, and only a battery maintainer can provide this. Third, you need a laptop with Windows 7. The reason is that in the real world, you are going to need to be mobile when it comes to reflash, and the more wires you have hanging all over the place, the greater risk you take of killing a module. Furthermore, most J2534 applications are transitioning from Windows XP to Windows 7. Windows 7 has an XP emulator that allows you to use applications that only work in XP. However, an XP emulator is very slow, so if you can get the reflash software running in Windows 7 itself, it’s best to stick with it. (See Fig. 1 and Fig. 2)

Q: Can I reflash all modules on all vehicles?

A: No, not really. Most manufacturers allow you to reflash PCMs and TCMs at most, so that you can solve an emissions issue. Now, reflashing a BCM has nothing to do with emissions, so they won’t support it.

There are some notable exceptions. Toyota and GM are two examples of manufacturers with a two-day, $55 subscription that allows you to reflash anything you want with the J-Box. (Fig. 3) Volvo and BMW are the same, but they are difficult to use and costly for some (Volvo is $225 for a few days).

Q: I have heard a lot of horror stories about frying PCMs.How do I avoid doing that?

A: Nissan recommends turning off your cell phone and putting a large piece of paper on the car that says, “This vehicle is being reprogrammed. Stay away!”

Now, you might not actually need to do this, but in the real world there are a few precautions you do need to take. In no particular order, here are a few. You should not be working with any tangled wires. Keep everything neat, because anything that might interrupt a reflash, like a lack of communication to a piece of hardware, can cost you the module, and you know you don’t want to have to pay for that. Always double check that your DLC, USB ports and power cables are fully connected and not jiggling.

Another precaution you should take is making sure your battery maintainer is hooked up properly to the vehicle’s battery or to the jump-starting posts. Make sure you plug it in where no one else in the shop might walk by and kick out the wire by mistake. (See Fig. 4)

Also, make sure that your laptop has its Windows, Flash and Adobe updates all completed before you reflash. If any of these begin in the middle of a reflash and reset your computer, this can cause problems with on-board modules.

Lastly, make sure that anti-virus software is disabled. If the program automatically opens up when you are in the middle of reflashing, obviously that’s not good. It’s best to have a laptop that you use exclusively for automotive use, so that you don’t need to worry about virus protection or programs that can cause conflicts with one another. (See Fig. 5)

Q: Where do I learn more about J2534 reprogramming?

A: There’s no shame in knowing that there’s always more to learn. Oftentimes it’s best to learn it by real-world experience, being taught by someone who knows how to actually do it on a real car. However, if no one is willing to make you their J2534 disciple, do not fear!

You can get some training from instructors at training events, whether they be regional associations (i.e., Technicians Service Training in the Northeast) or national events (i.e., VISION). There might even be a hands-on trainer in your area. Training DVDs from a few providers (such as Technicians Service Training and AVI) also cover the topic.

A few free resources exist online. DrewTech’s website ( and the “OTC Tool Guy” YouTube channel (See Fig. 6) are very good and cover car-line specific reflashing. OTC Tool Guy’s videos, for example, in about six minutes cover exactly how you register on an OEM website and subsequently carry on your reflash. They have a lot of essential, real-world tips. In their video on reflashing Nissans, they warn you that after a successful reflash, the software uses the word “failure,” and cautions the technician not to be afraid. That tip comes in handy when you reflash your first Nissan so you don’t freak out and think you fried the module.


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