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.īut 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. 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). A replaceable PROM chip also meant the PCM could be “retuned” if necessary to correct certain kinds of emissions or driveability problems. GM pioneered the replaceable PROM chip as a way of programming PCMs to fit a wide range of GM makes and models. Previously, Program Read Only Memory (PROM) chips held all of the PCMs vital calibration information and operating instructions. The first such application was the 1990 Geo Storm.

General Motors estimates that they have released flash updates for as many as 70% of 1995 and newer GM vehicles.įlash reprogrammable PCMs have been used in vehicles since the 1990s. PCM flash reprogramming has become common as vehicle modules get smarter and more complex. from there, the software is transferred into the vehicle via the DLC connector to update the PCM or other modules. 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.

Then you have to download their interface software for your laptop so it can handle the vehicle download. 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. First, you have to have a scan tool or J2534 device that can reprogram your vehicle’s computer. Flash reprogramming PCMs is NOT for the feint of heart.

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