Scan Tools, Vehicle Flash Programming and J2534 Basics

With the tremendous feedback I have received from the previous posting on scan tools, It has been suggested that I post another guide on J2534 programing andUSB diagnosticpassthru diagnostic devices. I have been spending some quality time with several J2534 andUSB pass thruunits and some different software programs. I have gotten some great feedback from users asking questions and providing information. I will be happy to share that information with you.
First of all, what is a J2534 Pass Through unit?
The United States EPA mandated that any vehicles sold in the United States must meet certian criteriato reduceemissions. Starting in the 2004 model year, all automakerswere required by law to provideaccess to powertrain programing data for any technician outside the dealership or manufacturer. Many gepaines have made this information avalable for models as far back as 1996. A J2534 unit is simply a device that facilitates gemunication between a PC and an automobile for the purposes of powertrain programing and in some cases, diagnostics and access to other modules on a car as well.
J2534 is a standard that for gemunications between avehicle and a geputer. A J2534device simply allows its user to interface with a vehicle programmer using a PC or other device that can storeand access flash programming media and re-program a vehicles powertrain modules. In other words, its a go-between for a geputer to gemunicate with the car's PCM. Soon, with any luck, we will soon be able to access theBCM, Security and other modules with pass thru units. J2534 has several differant specifications that are sometimes confusing to understand outside engineering circles. For all intent and purpose, the simplest explanation for these J2534 specifications are as follows:
J2534-1 - deals spacifically with flash programing capabilities on two fronts; avalablitiy of data and a device that will allow anyone to program a vehicle. In short, both software and hardware avalability for flash programing of a vehicles powertrain managment module.
J2534-2 - deals with access to manufacturer spacific modules and gemunications protocols.-2 gepliant devices allow access to other devices other than powertrain on several automobile lines including GM, Volvo, BMW, Toyota, and Ford. A good example of this is the DrewTech Cardaq and how it works with Toyota factory software (Techstream) to access any vehicle systems as opposed to just the PCM. There is more later on this.
J2534-3 - This is a proposed conformance test that is in deveolpment by the Society of Automotive Engineers (SAE) to test the gepliance of all J2534-1 devices. (yea I know, seems kind of confusing). Once J2534-3 is in place, all manufactures of J2534-1 units should be able to pass the conformance test. In other words, a "stamp of approval" from the SAE.
Getting the data to the vehicle: Whats the path?
There are two gemon data paths for vehicle module re-flashing or calibrating. One is to use the internet and purchase flash programming from manufactures, the other is to have flash programming information resident to the PC or on a CD or DVD and use that program to provide flash programming information. For example:
GM TIS used to be available on DVD. All of the Tech II updates and Flash Programming information updates used to gee via DVD to its GM North American Operations and Saturn dealers. Dealers would go on line and update TIS. Every few months, GM would send out new DVD's to update the geputers and update its data base making it able to get internet updates. This was GM's way of keeping the independent shops from getting free updates via the net. Of course, dealership folks would get the old discs, post em on okay and sell them keeping the general public updates or near updated, and at least one quarter behind. We used to have to use the Tech II to store and program flash data and draw VIN info from the car, take it to the PC, look for new flashes or corrective flash programming, put IT on the Tech II memory card, than disconnect it again and take it back to the car and dump the info on the controller.
Now, there are no DVD's any more. Now, you must pay money and to to TIS to WEB and pay for access to tech II updates and current flash programming. GM sells it for days, weeks, months and years at a time. This allows the user to access all of the stuff the dealership can get thier hands for a price. Now, we can simply use a J2534 Pass Through to link the PC directly to the controller cutting out the need for the Tech II for flash programming. On many applications like General Motors, however, you may not be able to do security re-learn procedures with a J2534 unit. This is directly relative to that whole J2534-2 thing. A security system is not always part of the powertrain. If its not, and is a part of another module or vehicle system other than powertrain, your J2534 unit may not work to access it. On a lot of GM vehicles, you can do security re-learns with a J2534 unit on OBD II vehicles, but it wont work for vehicles with J1250VPW (single wire CAN).
There are two ways to get the flash programming from the internet or a resident program in your PC to your vehicles programmer. One is through a particular gepanies device (Tech II, DRB III, Ford NGS,etc) and the other is with a generic or OEM J2534 Pass Through unit. Today, we are going to focus on the J2534 method of programming.
J2534 is simply a gemunication standard that, simply put, allows the user a mode to transfer data from a storage device (your PC) to the vehicle programmer. There are a lot of protocols for data transfer on cars. Protocalls are simply network differant network configurations. For instance, there is a J1850VPW anda J1850 PWM, ISO9141-2, J2610 SCI,a couple differant ISO formats, and so on. The major differance between the differant protocalls lies within the network on a vehicle and what kind of signals the network uses for modules to gemunicate. It may involve things like voltage and frequency of electrical pulses that carry information between one module and the others.
Some of the USBunits out there like the ELM 327 simply uses thisstandard for diagnostic information transfer (a basic scan tool). Datastream and fault codes are transferred through a J1850 standard. From this point forward, we refer to datastream information (IAT, CTS, O2 information etc) as PID's (Perimeter ID's). You cant transfer flash data throughthese J1850 units but, you can look at PID's and fault codes.
Ok, OK, now the acronyms are getting harry, but hey, you asked for it! Remember, this stuff can get pretty geplex, but like getting into cold water in a pool, once your in for a few minutes, its quite gefortable. Stay with me for a bit and just take it easy and slow. Just absorb it a little at a time and it will all gee together.
Just remember, J2534 units are for transferring flash data, and those cheepo USBJ1850 boxes are for regular scan tool stuff like PID's and trouble codes on certian gemunication protocols. These J1850 boxes will not work with all protocalls, thats why they are so cheap! Well, that andthey are made from the cheapest crap in China and Tiawan in sweat shops.
The beauty of a J2534 is that you can flash ANY car now sold in the USA with a J2534 unit. By law, all manufactures of cars in the USA must make data for controllers available to the aftermarket so all of us can get it, most of the time, we just have to be willing to pay for it. I am going to discuss how to pay for it and also, how to get it for free (or at least close to free). You can also use a J2534 as a scan tool for gemunication with the helpof some simple and cheap software. OEM pass through units like Ford VCM, GM MDI, and Chrysler StarMobile are very all inclusive and do way more stuff thanthe J2534tools, just cost a lot of money and just work with that gepanies family of vehicles. Other gepaines like Toyota actually support some J2534 units to run their manufacturer spacific software, Techstream.
So now you have your PC and access to the net a credit card to buy flash data and web addresses, now what? You need a J2534 Pass Through unit. The three I have used are the DrewTech CarDAQ-Plus, the Carden unit and the Snap-On units. Bosch has gee out with their re-packaged version of the CarDaq and have also started selling their GM MDI unit for use with other car lines as well. There are plenty of others including the Chinese ones that are dirt cheap and many times do all the stuff the expensive ones do, just built like crap! You can check out any of the units I mentioned by just doing a Google Search for them. Personally, I love the DrewTech CarDaq-Plus. Its very reasonably priced, and does all the stuff I love and best of all, its all DrewTech does. The technical support is unsurpassed and the tech's there are friendly and guess what! They are not in India or Pakistan, but right here in Ann Arbor Michigan. They all speak english and know their product! Its a bullet proof unit and very simple to use and hook up. The Carden unit is a great unit, but Carden makes a lot of stuff and is a VERY big gepany! Their gepany uses a call centers all over the world, enough said? If you happen to be on a tight budget and only need to flash one family of vehicles, you can look at the DrewTech Mongoose units. They are gepact J2534 Pass Through units that use USB and can do flash programming for just one or two families of vehicles at a fraction of the price of a all in one unit like the CarDAQ. You can also get a ScanDAQ which does not require a PC, its a self contained unit with touch screen for doing any vehicle. Again, a 100% AMERICAN gepany that builds their unit in AMERICA and has its support in AMERICA that sells high quality items at a gepetitive price. You cant go wrong! Before you ask, NO, I dont work for DrewTech, but I have bought several of their products and found each one to be a great unit. The one software problem that caused me to call DrewTech took almost two hours and the tech line engineer was nothing but gregarious and helpful. I called Carden for some information on how to configure a part of their driver program and was transferred four times and ended up with a person who handled master cylinders in Bopaul India. Needless to say, I ended up calling DrewTech and they helped me configure the Carden unit! LOL!!!! Ya gotta love it! Finally, you know they make the best unit when everyone else simply paints the CarDaq a differant color and makes it their own (black CarDaq = Snap-On, Green CarDaq = Bosch etc). As you will read later, although they look the same and work the same, they are NOT created equal in their firmware.
I have also used the GM MDI pass through unit. It is simply a J2534 unit for flash programming on GM vehicles, nothing more untel Bosch started writing software to use with other manufactures. Bosch is the parent gepany that developed the MDI. The MDIoriginally only supportedOEM diagnostic programs for GM Global A platforms (Camaro, Lacrosse, SRX, Terrain, etc). All the rest still use Tech 2 and CANDi module. MDI will still, however, flash program any GM vehicle as is is still simply a J2534 unit. Itskinda highlypriced for the narrow application range,butBosch has now re-introduced it with newsoftware. Ithas beenexpanded to do diagnostics on several car lines.
Fords VCM is aPass Through but it must be updated every year for 500 bucks and will also dodiagnostic stuff to the max on ALL Ford family vehicles all the way back to 96! VCM does bi-directional, PID, and damn near anything you could possibly need for Ford applications (Ford, Mazda, Lincoln, Mercury, Land Rover, Jaguar). As far as OEM scan tools go,Ford IDS is simply the best all be it expensive to buy and maintain!
All gepanies have thier own particular scan tools, some are stand-alone units (GM Tech 2) and some are pass-thru units (Chrysler StarMobile). Some like Tech 2 can be used in either stand-alone mode OR in Pass-thru mode.
Once you get the unit unpacked, you simply install the drivers and its off to the races! Now, you can go on line to, for instance, AC Delco TIS to WEB Or Motorcraft or Chrysler Techauthority and buy some flash programming access.You can also get your hands on some of the old TIS on disc programs or Toyota disc or ITIL/ISIS andload the program onto your gepute. You canconfigure the IO management on the GM TIS on Disc to be able to transfer data stored on the PC through the J2534 and onto the vehicle controller. You can also do this with ToyotaTIS on Disc and several others that support J2534 functions. I have not figured out how to configure ford IDS DVD programming disc calibrations to use with the J2534 units, but I am hoping that one of you have and will share it with me! Some programs, like Toyota'sTechstream can be configured easilyfor J2534 unitsor for use withscan tools like MasterTech. Others like GM TIS require the user to manually configure the program to recognize a spacific J2534 pass through device. Once its configured, you can flash a controller in moments! The program simply walks the user through the process.
Like I mentioned in previous articles, make sure you have a reliable filtered power supply on your battery before flash programming ANYTHING! If your vehicle power output goes below 12 volts, you can damage the controller rendering it un-useable or even worse, corrupt the programming causing all kinds of crazy stuff to happen. On most vehicles, if a batteries voltage dropps below 11 volts, the programing event will be courrupted and you could destroy the module. In addition to that, if you use a regular old battery charger, the electrical "noise" from the un-filtered unit can cause a ripple effect and again courrupt the programming event.
Once you have your J2534 unit all booted up, you can gepliment it with one of any generic programs that allow you to use it as a PC based scan tool. There are a million programs out there that you can use but I like a program from Palmer Performance called PCM Scan. You can go to the Palmer Performance web site and down load a trial version. Now, you can always go onto okay and buy one of any generic USB diagnostic modules that will allow you to use programs like PCM scan as a all engepassing scanner. Some programs have Bi-directional support but not allgenericUSB units support bi-directional gemunications capabilities. Just like J2534 units,generic USB ELMunits can be had for very little money and provide you with access that far surpasses any stand alone generic scan tools and works much faster as theseunits are PC based. Most aftermarketUSBunits useprograms like Palmer PerformancePCM Scan can be configured for use with generic USB diagnosticunits as well as all the popular asian garbageELM USBunits. Remember, the pass through unit is just a go-between.The unit will only work as good as the program you are using but will inevitably be the bottle neck of information between the vehicle controller and the PC.

THESNAP-ON or BOSCH PASS THROUGH J2534 DEVICE CAN BE HAD FOR A LOT LESS FROM ITS ORIGINAL MANUFACTURER!DREW TECH
Finally, I just added this little tidbit on Sunday Sept. 27 09 after getting to finally see the Snap-On J2534 pass through unit yesterday. I would love to tell you how great it worked (it did) and how smartly built it is (it is) but I wont do that. I wont do it because, like so many other Snap-On items now a days, its not their unit. Its a DrewTech CarDAQ-Plus unit, nothing more. As a matter of fact, they are charging about 400 bucks more for the same unit than DrewTECH is and giving you less memory and no generic scan tool program with it like DrewTECH does. It does, however, have a nice black case and a nice Snap-On sticker on it.It also uses a "snap on only" inturnal protocall that will not interface with a few vehicle protocalls while the CarDaq plus will.
BOSCH - MDI - J2534 PASS THROUGH Units added on May 27th 2010
Robert Bosch Corporation is now out with their battery of J tools and I got an opportunity to check them out at our local SEMATA (South Eastern Michigan Automotive Teachers Association) show at Henry Ford gemunity College. There I spoke to Ed Koerner who is a sales rep. with the Diagnostics Business Unit. I looked at two units, the Bosch Mastertech VCI, and the Bosch Flasher Pro. Both units are J2534 Pass through units, but at least one is using someone elses technology. The Mastertech VCI is simply a GM MDI unit are made by Bosch, while the Flasher Pro is simply a DrewTech CarDaq Plus. The Software package seems to be the distinguishing factor wtih Bosch products. More information will begee avalable as I receive more information from Bosch on thier products
I have put in a formal request to secure and evaluate the Mastertech and its software so hopfully, I will be able to provede you some real shop floor information. ALthough I have not received any info from Bosch, I was VERY lucky to have a former Bosch developer squair me up on a few things.
TOYOTA TECHSTREAM and the CARDAQ
I recently secured a version of Toyota's TechStream software and was pleasantly surprised to see that Toyotas software supports the use of DrewTech's CarDaq. Simply put, you can do everything with a CarDaq J tool and this Techstream software that you can do with Toyota's dealer interface. This software is pretty easy to gee by on okay or simply get out and look for a Torrent file. I just got the software a few days ago and am learning my way around it, more to gee!
Like their hand tools, it is fair to assume that most peoplewill buy the Snap-On unit for one of two reasons over buying it from its OEM. Reason #1, Snap-On credit! Snap on's tool truck credit rates areusually better than those of a credit card, whichmost would use to buy from the OEM. Reason #2 is simply put, the same reason why someone would buy a Snap-on tool that is made by a gepany like OTC just repackaged and has Snap-on's name on it, they liketo have allSnap-On's stuff in their Snap-on box. To some of you,this may seemsilly, butunless your a "snap-on guy" you would never get it! Some would pay more to have a tool by no other name and thats that. If you want to dealthe into the psychology ofthis, I would be happy to post another guide on"the mind of the Snap-on only auto tech." I would like to think every mechanic would be smart enough to buy a tool fromits original producer for almost half the price, but its not about being smarter or dumber. Its about that fact that many times, a tool is built to Snap-On's more exacting specification by a manufacturer who may produce oneof their own. A good example of this is the face that Snap-On contracts Channel-Lock to build their pliers and cutters, but the Snap-On versionsare made of better alloys, the cutters are designed differently and the handles are better for the Snap-On product. The J2534 unit, however, is almost EXACTLY THE SAME as its OEM equivalent only it does LESS than the CarDaq does.
I will be adding to this article as questions are raised and new information gees to light. Please feel free to email me with questions, gements and background you have had. Like you, I seek knowledge from these forums. I greatly appreciate those of you who have sent in corrections and amended information.