Would you believe for over a decade flash reprogramming has been the way to reprogram your  ECM? The introductory application was the 1990 Geo Storm. Perhaps GM could have chosen a more luxurious or performance oriented vehicle like a Buick Roadmaster or Corvette to introduce the new technology. The choice probably had a lot to do with production scheduling and new model introductions than anything else. Until this point searching for an ECM for sale was not necessary for repairs or upgrades.

GM knew OBD II was on the way and a new generation of ECMs that were faster, with easier and larger capacities capable of efficient programing through  more  advanced computerization programming technology.

Until this point, 1995, Program Read Only Memory (PROM) chips were insertable and contained the information required to operate the portions of the car  that were controlled by the ECM.

GM pioneered the replaceable PROM chip as a way of programming a limited number of basic 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 emission or driveability problems. It also meant that if a virus or bug that was later discovered in the original factory programming it could be corrected in the shop by simply replacing the original PROM with an updated corrected PROM

But replaceable PROMS had a major flaw, there were too many of them! Every model year and every running change meant another PROM had to be made. Every fix or recall for an emissions or driveability problem added more part numbers to keep track of. We’re talking thousands of different PROMS.

Introducing the flash reprogrammable EEPROM (Electronically Erasable Program Read Only Memory) chips allowed the new breed of ECMs built with EEPROM chips to be reprogrammed in a matter of minutes without having to remove the ECM or replace a single chip. It’s all done by a computer with the proper access codes and input data.

GM began phasing in ECMs with flash reprogrammable chips in a variety of cars and trucks. By 1995, all GM cars and trucks had the flash reprogrammable ECMs. Ford and Chrysler were also dsigning similar setups as OBD II became the universal, global standard in 1996. Today, almost all ECMs have reprogramming capabilities so changes and upgrades can be made if needed. That’s over 100 million vehicles that have been built since 1996.

In certain events the ECM can have a solid state cicuitry failure, which can only be corrected by replacing the ECM. The important part about ECM replacement was making sure it was programmed to the most cuurent specifications for your particular car. Which at the time could only be done by the dealer with the specialty equipment released only to dealers at the time.

My advise should you need a replacement ECM would be to buy a good used ECM for sale. My experience has been that purchasing one from the dealer is highly expensive and, in most cases it costs extra to have the new ECM programmed, since they are not pre-programmed. We began to purchase good used ECMs from GotEngines.com. Why? Because they literally cost pennies on the dollar in an already programed ECM, which is taken off a car which matches your cars VIN in respect to ECM identification. More interesting is that you get the same warranty with a good used ECM as you would if you bought  a new one from the dealer.

We were very successful taking this avenue. Customers were thrilled to pay $100 to $200 for a guaranteed good used ECM as opposed to $500 and up to over $1000 for a new one. Well, hopefully this information will be of help to you someday. If you are interested in reading more about your car and ECM articles take your time to read more of our GotEngines.com Blog. Good luck with your repairs.