Flash reprogramming PCMs is NOT for the feint of heart. First, you have to have a scan tool or J2534 device that can reprogram your vehicle's computer. Then you have to go to the vehicle manufacturer's service information website, pay an access fee and find the correct update for your vehicle. Then you have to download their interface software for your laptop so it can handle the vehicle download,. Once that has been installed on your laptop, you can download and transfer the new PCM or other module programming to the J2534 interface tool or scan tool. from there, the software is transferred into the vehicle via the DLC connector to update the PCM or other modules. PCM flash reprogramming has become common as vehicle modules get smarter and more complex. General Motors estimates that they have released flash updates for as many as 70% of 1995 and newer GM vehicles. Basic steps of flash reprogramming a vehicle computer. PCM Programming is Nothing New Flash reprogrammable PCMs have been ussed in vehicles since the 1990s. The first such application was the 1990 Geo Storm. Previously, Program Read Only Memory (PROM) chips held all of the PCMs vital calibration information and operating instructions. GM pioneered the replaceable PROM chip as a way of programming PCMs to fit a wide range of GM makes and models. A replaceable PROM chip also meant the PCM could be "retuned" if necessary to correct certain kinds of emissions or driveability problems. It also meant that if a bug was later discovered in the original factory programming, it could be corrected in the field by simply replacing the original PROM with an updated corrected PROM (a tactic GM has successfully used over the years to fix many factory flaws). Performance enthusiasts also liked replaceable PROMs because the chip could be replaced with one that provided more spark advance, fuel enrichment, a higher rev limit, etc., to squeeze more power out of the engine. But replaceable PROMS had a serious drawback: there were too many of them! Every model year and every running change meant another PROM had to be created. Every field fix or recall for an emissions or driveability problem created more part numbers to keep track of. We are talking thousands of different PROMS. The General Motors PROM Identification manual that OTC used to provide with their Monitor scan tool and Pathfinder software contained more than 362 pages of GM PROM numbers! Enter the flash reprogrammable EEPROM (Electronically Erasable Program Read Only Memory) chip. PCMs built with EEPROM chips can be reprogrammed in a matter of minutes without having to remove the PCM or replace a single chip. It is all done digitally with the proper access codes and input data. Following the Geo Storm, GM began phasing in PCMs with flash reprogrammable chips in a variety of cars and trucks. By 1995, most GM models had the flash reprogrammable PCMs. Ford and Chrysler were also doing the same thing as OBD II arrived on all cars and light trucks in model year 1996. Today, virtually all PCMs have reprogramming capabilities as do many other onboard control modules (ABS, air bags, climate control, body controller, etc.). This allows changes and upgrades to be made as needed. Why Reprogram PCM? PCMs may need to be reprogrammed for several reasons. One is to fix factory bugs. Every time Bill Gates rushes yet another version of Windows to market to perpetuate the Microsoft revenue stream, it always turns out to have bugs and security holes that were somehow missed but must be fixed by downloading and installing the latest Windows "service pack." It's a never-ending cycle of upgrades and patches. Fortunately, it is not that bad yet with automotive PCMs, but it has become a crutch for automakers who rush products to market that aren't quite ready. This philosophy of "build it now and fix it later" creates a lot of unnecessary recalls, but at least it gives technicians a way to fix factory mistakes without having to replace any parts. A reflash may also be required if the factory settings for the OBD II self-diagnostics turn out to be overly sensitive – especially after a few years of operation. The same goes for driveability. What works fine in a brand new car many not work so great after 50,000 or 100,000 chilometri of real-world driving. Changing the fuel enrichment curve, spark timing or some emissions control function slightly may be necessary to eliminate a hesitation, spark knock or other condition that develops over time. For example, on certain GM vehicles the Check Engine light comes on and sets a code P1406 that indicates a fault in the position of the exhaust gas recirculation (EGR) valve. Cleaning or replacing the EGR valve and clearing the code does not fix the vehicle because the code usually returns. The real problem is the OBD II programming in the PCM. When the PCM commands the EGR valve to open to check its operation, it isn't allowing enough time for the valve to respond. A brand new valve takes only about 50 milliseconds to open but an older valve may take up to 350 milliseconds or longer – which is not long enough to cause a real NOx emissions failure but is long enough to trip a fault code. The fix in this instance is to reflash the PCM with new instructions that allow more time for the EGR valve to respond. Another example are rich codes that may appear on some late-model GM vehicles. The problem here is that the original OBD II self-diagnostic programming does not allow enough leeway for changes in intake vacuum that occur as the engine ages. After 60,000 chilometri, intake vacuum isn't as high as in a new engine, which can create a rich fuel condition. The cure is to flash reprogram the PCM to compensate for the drop in vacuum. When vehicle manufacturers calibrate the onboard diagnostics to meet federal emissions standards, they have to draw the line somewhere as to what operating conditions might cause emissions to exceed federal limits 1.5 times. That is the threshold where a fault code must be set and the Check Engine light must come on. It doesn't mean emissions really are over the limit, but it is possible based on laboratory dyno testing and field experience. Depending on the application, the vehicle manufacturer may even set the limit a little lower just to be safe because the last thing any OEM wants is an expensive emissions recall. The best advice when confronted with a troublesome code that keeps coming back or seems to set for no apparent reason is to check for any technical service bulletins that may have been published. Chances are it might be a programming issue that requires a reflash to fix. Something else to keep in mind with respect to many late-model flash reprogrammable PCMs: if you replace the PCM for any reason, the replacement unit may have to be reflashed before it will start the engine! Some modules are plug-and-play, and are preprogrammed by the dealer or aftermarket parts supplier so they can be installed ready-to-go. But many need vehicle specific calibration information to run properly. This may require downloading old calibration information from the original PCM (if possible) and reloading it into the replacement PCM, or getting updated calibration information from the vehicle manufacturer to install in the new module. If you are buying a reman PCM from an aftermarket supplier, they may be able to program it for you. The information they need to do this includes your year, make and model of vehicle, engine size, vehicle identification number (VIN), the type of transmission (manual or automatic), the emissions type (federal certification or California), and other options that may affect the calibration of the PCM. Your other option is to have a car dealer or repair shop reflash the computer, or attempt it yourself. Who Can Do PCM Reflashes Historically, car dealers have been the only ones who had access to the tools and software needed to reflash PCMs. Thanks to the passing of Senate Bill 1146 in September 2000, vehicle manufacturers must now make this technology available to independent repair shops and individuals at reasonable cost. Starting in 2004, flash reprogramming procedures also had to conform to SAE J2534 standards that allow the use of aftermarket scan tools or similar pass-through devices. Starting with the 2020 Corvette C8, flash reprogramming is transitioning to "over-the-air" updates, similar to what Tesla has been doing for a number of years on its vehicles. Ford said the 2024 Mustang will also be their first to use over-the-air reprogramming. What's more, the auto makers will be encrypting their computer code to make it harder for people to hack into the factory calibrations to make performance modifications. So everything we cover in this article will eventually be obsolete! PCM Reflashing Requirements Reflashing PCMs requires three things: a scan tool or J2534 pass-through device that is flash capable, a Windows laptop computer (Most require Windows 7 but some older applications may require Windows XP) with an internet connection for downloading the flash software from the vehicle manufacturer website (Click Here for a list of OEM Service Websites & Access Fees), and a subscription to the manufacturer's database so you can access the software for the laptop and the vehicle. Other items that are needed include a cable to connect the laptop to the scan tool or J2534 pass-through device, and a cable to connect the scan tool or J2534 pass-through device to the OBD II connector on the vehicle. You will also need a battery power supply source or charger that can maintain a steady constant voltage to the vehicle during the reflash procedure. You do NOT want any voltage drops for fluctuations during the reflash because it may screw up the programming of the PCM. For older GM applications, you can use a Tech 2 scan tool or Vetronix scan tool or other aftermarket J2534 pass thru tool. For older Ford applications, you can use a Ford New Generation Star (NGS) scan…

Fonte: AA1Car.com