Electrical System Totally Quits When Cranking Ignition and Won't Come Back On Without Resetting System

[ImprezaUgh]

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.

 

[bmart]

No good ideas other than you may have more than one issue going on.

Part it out and get something else fun!

 

[Raymond3006]

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.

#1) From your Description(s) , it sounds like you have all the Skills necessary to Work as a Repair (Re-Manufacturing -!) Technician at the nearest SUBARU Dealership . at least you'd get a discount ( ??? ) for "burning" thru PARTS !!!

#2) Given The-Age of your vehicle, the mileage , and (likely) previous and on-going Work .... I'd say yours is a TYPICAL example of a Ground System Gone (and getting WORSE !) BAD ! The BEST way to deal with this ... is to become An EXPERT ( !!! ) on your Vehicles Maintenance Electrical Diagrams , especially the ENTIRE GROUNDING SYSTEM !

THEN , take each System (as delineated in the MAINTENANCE DOCUMENTS ( not trouble reporrts , but the 5,000-to-8,000-PAGE (entire !) Maintenance BOOK , and check each for ON/BUT-NOT-RUNNING-VOLTAGES , using a DIGITAL VOLT METER for : (a) Resistance Measurements , (b) Voltages.

Be advised , that there are TWO VOLTAGE SYSTEMS in all modern (ECM) Vehicles : there is the Bulk-Power 12-Volt-System ; and there is an Electronic 5-Volt-System (mostly used for Sensors , from Front to Back : and mostly they EACH use the Same Ground System , which used to be Welded Frames, &/or Mig Welded Sheet-Metal (SM) Panels. Today, many Vehicles are assembled by Jigging loose pieces onto a Manufacturing Frame, applying ONLY a couple Spot Welds , and they Hydraulically apply what is ESSENTIALLY HOT JB-WELD EPOXY on all the Seams ..... ! Not the best plan for long term RELIABLE GROUNDS that do not use "moderate" thickness copper wire for the Actual Functioning Ground System !!!!!

Good Luck finding the cause of a problem that has all the indications of a multi-headed-Medusa trying to bite you at every turn ... ! BTW , I have TOTAL WRATH against the "modern" training of REMANUFACTURING MECHANICS that burn-out more Good-Stuff, than Trouble-Shooting Mechanics that actually find out what IS WRONG FIRST , then fix it with a Single Piece of New-Stuff ... !!!

 

[ImprezaUgh]

#1) From your Description(s) , it sounds like you have all the Skills necessary to Work as a Repair (Re-Manufacturing -!) Technician at the nearest SUBARU Dealership . at least you'd get a discount ( ??? ) for "burning" thru PARTS !!!

#2) Given The-Age of your vehicle, the mileage , and (likely) previous and on-going Work .... I'd say yours is a TYPICAL example of a Ground System Gone (and getting WORSE !) BAD ! The BEST way to deal with this ... is to become An EXPERT ( !!! ) on your Vehicles Maintenance Electrical Diagrams , especially the ENTIRE GROUNDING SYSTEM !

THEN , take each System (as delineated in the MAINTENANCE DOCUMENTS ( not trouble reporrts , but the 5,000-to-8,000-PAGE (entire !) Maintenance BOOK , and check each for ON/BUT-NOT-RUNNING-VOLTAGES , using a DIGITAL VOLT METER for : (a) Resistance Measurements , (b) Voltages.

Be advised , that there are TWO VOLTAGE SYSTEMS in all modern (ECM) Vehicles : there is the Bulk-Power 12-Volt-System ; and there is an Electronic 5-Volt-System (mostly used for Sensors , from Front to Back : and mostly they EACH use the Same Ground System , which used to be Welded Frames, &/or Mig Welded Sheet-Metal (SM) Panels. Today, many Vehicles are assembled by Jigging loose pieces onto a Manufacturing Frame, applying ONLY a couple Spot Welds , and they Hydraulically apply what is ESSENTIALLY HOT JB-WELD EPOXY on all the Seams ..... ! Not the best plan for long term RELIABLE GROUNDS that do not use "moderate" thickness copper wire for the Actual Functioning Ground System !!!!!

Good Luck finding the cause of a problem that has all the indications of a multi-headed-Medusa trying to bite you at every turn ... ! BTW , I have TOTAL WRATH against the "modern" training of REMANUFACTURING MECHANICS that burn-out more Good-Stuff, than Trouble-Shooting Mechanics that actually find out what IS WRONG FIRST , then fix it with a Single Piece of New-Stuff ... !!!

Thanks for your reply, Raymond. It's definitely easier to throw parts at it rather than spend the painstaking time to figure out the root issue. I suspect my Impreza does have a major issue with the ground system. I'll have to download the full service manual and do my homework on the voltage systems before proceeding. Let the good times roll.