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08 forester xt AT :(
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11 Posts
Discussion Starter · #1 ·
i have searched, threads and google. nothing conclusive.
here we go...

*CURRENTLY IMMOBILE* parked at the side of the road, down the street from my house, conveniently.... :icon_mad:

2008 Forester 2.5XT Sport
4EAT

Mods:
Fujita Short Ram Intake
K-Sport Coilovers
Upgraded Soundsystem:
rockford fosgate 400 watt + pioneer 500 watt mono sub amp (nothing crazy but will put strain on the battery at times :S)

Symptoms:
-started with funny shifting, very seldom. once every 3 days or so for the past 2 weeks
-currently sitting on the side of the road, not able to drive, will not start; turn the key, runs for a second then dies
-relays (unsure which relays at this point) are going flicking on and off (proper terminology lol) very rapidly with key in and "on"
- pull key out and relays still flicking on and off for 5-10 seconds

Codes: *was not able to scan first try; reader went all funky. pulled the (+) terminal off the battery for 15 minutes, reinstalled, turn key "on" (not start) was then able to read codes.
- P0725 Engine Speed Input Circuit Malfunction
- p1718 AT CAN Communication Circuit

friends tell me battery, owner of subaru tells me battery/alternator, my gut tells me otherwise.

there are tons of posts regarding this problem on many different forums but no solutions... lets find out what this problem is and get our beloved Fozzy's back on the road!!

thanks guy's!
 

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1999 Forester 5MT
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856 Posts
Battery sounds like it is dead. Could be a bad battery, or it could be a bad alternator not charging it. Your best friend right now is a multimeter. Charge the battery on a charger and start the vehicle. See what the voltage is. If it's ~14v, then the alternator is good. If it's lower, then the alternator is no good.

If the battery won't charge right, there's your problem. It's possible the audio system over time has done damage to the alternator, battery, or both.
 

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08 forester xt AT :(
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11 Posts
Discussion Starter · #3 ·
I replaced the battery last night, still nothing. Funny thing is now, when I put the key in and start it, it turns over but doesn't even try to start. Even worse, now the obd scanner won't read the ECM. I swapped out the crank sensor with one from an older wrx (identical) and it seemed to make things a little better, as in the relays weren't going crazy. I did manage to get it towed to my local Subaru dealer so hopefully we'll get to the bottom of this sooner than later!
 

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08 forester xt AT :(
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11 Posts
Discussion Starter · #4 ·
Oh and I did take a multimeter to every fuse, battery, alternator... Pretty much everything I could get a reading on. Everything was showing normal voltage, ~12v off the battery, ~14v off the alternator.
 

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Administrator
2004 Forester XT Premium 4EAT
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29,431 Posts
If I had to guess I'd say either your ECU or TCU (or both) are bad.
 

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08 forester xt AT :(
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11 Posts
Discussion Starter · #6 ·
Turns out it is the ECM. Somehow it fried.
GET THIS!
A service advisor at my friendly neighbourhood Subaru tried say it was my fault to try and get me to fork over the $1400 + tax... on top of the full bumper to bumper ~$3000 warranty I paid for when I bought car. "I hooked the battery up backwards." While I was driving.... Huh? And so you all know, according to this service advisor, an ECM is abbreviated for Emissions Control Module. Not Electronics Control Module, as we had all been taught.. HAHA! Although it will after all be covered under warranty, I will not be returning to said Subaru dealership for service to my vehicle. I've had nothing but problems the few times I have gone in for service.

So that aside, my worry is now WHY? Why did the ECM all of a sudden decide to croak? It's obviously not a very common problem with any car, just a coincidence? Or will it likely happen again once the ECM is swapped out?
 

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2006 Forester XT Limited 5 Speed Manual
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524 Posts
Was the old battery ever load tested? I could be that the when the battery was low or failed, as the car was started, the voltage dropped to a low enough point and the ECM tried to continue to opperate, forcing power consumption up (Ohm's law) and frying something internal.

Even if you swapped out the battery, I would still have it tested. Most auto parts stores will do the load test free of charge. I'm only guessing that you hadn't turned the old battery in for a core exchange on the new one.
 

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08 forester xt AT :(
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11 Posts
Discussion Starter · #8 ·
Well we did put a multimeter on the old battery while it was installed. Tested 12.4v then dropped to 9v while starting. I haven't done a proper load test on it but I do still have the battery so I will do that when I take it back for core. Also, when I picked my forester up last night I spoke to the service manager. He said his mechanic told him the reason the ECM fried was do to an unusually high resistance in one of the grounds. So I was told they traced that wire/ground, replaced it and the ECM and all should be fine now. I will update though once I have had the battery load tested. Thanks for your help guys!
 
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