Chrysler Diagnostic Tool Drb' title='Chrysler Diagnostic Tool Drb' />PCM Flash Reprogramming Procedures Home. Auto Repair Library, Auto Parts, Accessories, Tools, Manuals Books, Car BLOG, Links, Index. Copyright AA1. Car Adapted from an article written by Larry Carley for Underhood Service magazine Flash reprogramming PCMs is NOT for the feint of heart. First, you have to have a scan tool or J2. Then you have to go to the vehicle manufacturers service information website, pay an access fee and find the correct update for your vehicle. Then you have to follow the exact procedure to download and install the update into your vehicles computer. PCM flash reprogramming is becoming more and more necessary as vehicle modules get smarter and more complex. General Motors estimates that they have released flash updates for as many as 7. GM vehicles. PCM Programming is Nothing New. HTB1PKF6IpXXXXbMXpXXq6xXFXXXt/Professional-diagnostic-tool-for-Chrysler-Diagnostic-Tool.jpg' alt='Chrysler Diagnostic Tool Drb' title='Chrysler Diagnostic Tool Drb' />Once you eliminate the impossible, whatever remains, no matter how improbable, must be the truth. Sherlock Holmes. Flash reprogrammable PCMs have been ussed in vehicles since the 1. The first such application was the 1. 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. Vehicle to Diagnostic Tool Reference Chart Year Body Name Scan Tool Year Body Name Scan Tool 2014 ALL ALL wiTECH 2006 HB Durango wiTECH 2013 ALL ALL wiTECH. 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 3. 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 1. 99. 5, 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 1. 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. Its 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 arent 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 5. 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. Free Physics Simulation Software more. For example, on certain GM vehicles the Check Engine light comes on and sets a code P1. 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 isnt allowing enough time for the valve to respond. A brand new valve takes only about 5. 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 6. 0,0. 00 miles, intake vacuum isnt 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. That is the threshold where a fault code must be set and the Check Engine light must come on. It doesnt 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.