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- Mar 19, 2025
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I have 2008 Impreza 2.5i that has had an intermittent issue with all the dash warning lights coming on while driving. It wouldn't affect drivability and it would always go away for awhile if I reset the electrical system by briefly pulling off the negative battery terminal. However, recently all the dash lights came on while driving and the engine began to sputter if I wasn't easy on the throttle. Everything went back to normal once I pulled over and removed the negative battery terminal, but I figured it was probably time for an ECM replacement.
I sourced a used OEM unit from a local used parts dealer with the same Subaru part number that was tested as working. I decided to plug it into my car this afternoon without cloning the old ECM, simply to see if it would work. I knew that it probably wouldn't and that I'd simply have to plug back in the old ECM and go have it cloned by a local repair shop. After installing the replacement ECM and reconnecting the battery terminals, the electrical system turned on as normal during the first 2 clicks of the ignition, but when I attempted to actually start the engine, the car wouldn't crank and the electrical system completely died and remained dead until I reset the system by removing the negative battery terminal. I then reinstalled the old ECM to see if the engine would start. Once again, the electrical system worked on the first 2 clicks but died upon cranking the ignition and wouldn't come back on until I disconnected the battery again. There is no immobilization warning going on, the car is stone cold dead.
Any ideas on what is causing this electrical system issue? The battery has plenty of charge, the terminals are clean, no fuses under the hood appear to have blown, and I always removed the battery terminals before trading ECMs. I don't understand why it won't run with the original ECM installed again, as it never had a problem starting before. I'd hate to junk the car, but with 150k on the clock and having spent much of its life in the Northeast, this thing isn't worth fixing if it can't be done cheaply. Thanks for your help.
I sourced a used OEM unit from a local used parts dealer with the same Subaru part number that was tested as working. I decided to plug it into my car this afternoon without cloning the old ECM, simply to see if it would work. I knew that it probably wouldn't and that I'd simply have to plug back in the old ECM and go have it cloned by a local repair shop. After installing the replacement ECM and reconnecting the battery terminals, the electrical system turned on as normal during the first 2 clicks of the ignition, but when I attempted to actually start the engine, the car wouldn't crank and the electrical system completely died and remained dead until I reset the system by removing the negative battery terminal. I then reinstalled the old ECM to see if the engine would start. Once again, the electrical system worked on the first 2 clicks but died upon cranking the ignition and wouldn't come back on until I disconnected the battery again. There is no immobilization warning going on, the car is stone cold dead.
Any ideas on what is causing this electrical system issue? The battery has plenty of charge, the terminals are clean, no fuses under the hood appear to have blown, and I always removed the battery terminals before trading ECMs. I don't understand why it won't run with the original ECM installed again, as it never had a problem starting before. I'd hate to junk the car, but with 150k on the clock and having spent much of its life in the Northeast, this thing isn't worth fixing if it can't be done cheaply. Thanks for your help.
