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i bought a 2007 forester, 2.5 liter, 5 speed,about a month and half ago, i love it, it drives great.
we needed a bigger car since my wife and i have a newborn baby girl, 4 months ago and my mustang was too small for a babyseat.
but just as i was going to get it inspected here in nyc, check engine light came on.
error code was for a fuel pressure solenoid low voltage input. so i bought the part replaced it,error code came back.
so after studying a downloaded wiring diagram of the whole car, figured out it was a bad connection from harness under back seat to the valve.
so i replaced it and checked connections to harness using the relay test mode (green plug under dash).
everything seemed ok, put everything back together but car wont start, obd reader doesn't read the car anymore, and car sometimes cranks with key but won't start.

this is driving me nuts, studied the diagram and swapped out starter interlock relay with horn relay nothing, still the same.
this was an act of desperation because sometimes starter cranks about 2 revolutions with key thus telling me starter interlock relay is good.
also since i put everything back together relay test mode doesn't work when you plug in both green plugs under dash.
i checked every fuse still wont start, but cranks every third try, and cant recognize obd 2 reader, but powers up my reader.

i hate electrical problems like this, i have tried everything i can think of and would appreciate any help on this.
i am in new york and staying home due to coronavirus scare here, but on call from work if needed for emergency, so far no need since my unit is shut down for a few weeks.
so i have time to work on this in the driveway.

thank you

Ron
 

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While wrestling under the dash, you may have knocked something loose. It could also be totally random. Stuff rots away in the North East. I know: I'm in CT about 40 miles from you.

I'd first make sure you are consistently getting power. When it doesn't start, does the dome light come on when you open the door?

Even if you're getting power, it doesn't mean the connections can actually do current:
I'd check the ground connection from the battery to the rest of the car. To verify this connection is good, get a booster cable. Do NOT use the RED lead - let it dangle. Tie the black lead to the NEGATIVE battery post. Tie the other end of the booster cable's BLACK lead to a bare beefy part of the engine, like the alternator bracket. See what happens. See if you have OBD2 connectivity and/or whether it starts. If it does something more, you likely have a bad ground from the battery to the frame.
The negative terminal, as long as you're careful and do what I just told you, is fairly benign.

I am not encouraging you to do something similar with the positive terminal, not knowing anything about your skill level yet: I'd be reluctant to tell you how to test it for fear of something going totally sideways.

You have an OBD2 reader - good. Do you have a multimeter?

Edit: and a belated congratulations on the birth of your daughter! That's great!
 

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Discussion Starter #3
Thank you for everything, my daughter is very happy, she is our first baby so the grandparents on both sides call all the time.

As for my skill level, I have been working on cars since I was 12, learned from my dad he had 5 old cars at one time we always had projects goong on. It was his hobby also he was a computer analyst, i work as an engineer for city but I love cars and automotive work but hate electrical problems like this.

The car works fine dome lights everything, fans, radio, ppwer locks, window all working fine.
Only thing is she won't start, every third crank starter cranks twice but car won't start. I tried putting it in relay test mode with green plugs but since that day I put it together relay test mode does nothing, car won't start and one reader doesn't recognize computer but gets power to reader from plug.

Thinking it might be something with one of the relays or ignition switch, or some security module people mention in forums. I am new to Subaru and don't know their quirks or tricks. I had jeep, vw/audi, Honda, ford, rrnault, also growing up dad had gm's (Cadillac chevy buick). But this is my first subaru. 2 friends of mine had them and loved them, i tuned up a friends outback years ago.

I will try the battery cable ground when i get home currently taking my mother to a doctors appt
 

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As for my skill level, I have been working on cars since I was 12..
Good to know.
Please don't take it the wrong way: I just didn't want to get into a dissertation that isn't understood or couldn't be executed. To some that might be too much, like drinking out of a firehydrant. It would be a waste of water and frustrating. Good - we're on the same page.

Regarding that OBD2 issue, it should just plug in and go. Even with security features enabled, OBD2 will work.
It may be worth pursuing. It runs CANBus with some protocol bolted on top. We don't care about the actual protocol. That's what the reader takes care of. That's not our problem.
The physical network is twisted pair, differentially driven and it should have 120 ohms resistors on each end -- so you should measure 60 Ohms on the bus. On long networks, not having proper termination will cause all sorts of issues (I've done a fair bit of CAN work and seen work badly or not at all).

Let me dig out some schematics on it.
 

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Discussion Starter #5
i dont have a repair manual, just subaru manual that came in glove compartment, very basic stuff, and a wiring diagram of whole car i downloaded a week and a half ago.
 

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Regarding WI-171, I was thinking it would help you troubleshoot as to why OBD2 isn't working:

Notice that the CAN bus runs parallel across the steering angle sensor, the TCM, ECM and the VDCCM. I'd imagine that the car would refuse to run if that bus isn't going to all those modules. There are interconnects (B246 amd B312) that could have an issue, for instance. The steering angle sensor has its own 'joint connector' B311. It clearly lifts it from ground, taking that subsystem off the bus. I don't know whether that would throw the ECM for a loop but worth looking at.
Those interconnecots are under the dash, where you have been poking around.

I'd measure resistance across that bus with the key off and see whether you see 60 ohms. If so, turn the meter to read DC volts and turn the car on. There is data flying back and forth on that bus but it is really fast so the meter won't be able to read those changes but will average it.. As such, your DC multimeter will likely read around 2.5V.

It is a bit weird that the test connector doesn't do anything.. You hooked those green connectors under the dash up and nothing happened, right? I'm not sure what sort of dependencies that connector has for it to turn on all the relays in the system - if it is truly a test connector, one would imagine it wouldn't care.

That test connector not doing its thing, it not starting and the OBD2 being silent points in the direction of the ECM.
I'm not suggesting it is dead but a major connection to it is likely missing: Maybe that CANBus, a power/ground connector, etc. I'd start there.

**** Edit
Not sure whether you looked in this direction and we may have dove into a rabbithole, totally ignoring what Occum's razor theory has taught us:
I'm wondering whether it could be something as stupid as the ignition switch..
It powers up the ECM when you turn the key on, it clearly starts the car.
If that switch is truly defective, you wouldn't get OBD2 communications, etc.
If you turn the key on, do the dash lights, radio, etc come on? If so, the ECM should have power at that point.

You mentioned the starter relay before, I believe. That just runs the starter. Important, yes, but the ECM is supposed to have power before anything will run.
Here's the starter circuit. Pretty simple:
531774


Here's the ignition switch and related stuff. I'd make sure that you have something on the pin that I've colored green. Notice there's an interconnect F46 - that could have been knocked off. I'd imagine it is near the steering column.
If you see a voltage there, check what happens to the connections colored red, while you have the key in the ACC position.

531775
 

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Discussion Starter #7
thanks rem, i just spent a few hours on the phone with a friend jim, who lives upstate, he is a mechanic and we checked a whole lot of relays and electrical connections with him on the phone and video messenger. we checked that circuit you sent me above also. jim is a mechanic and a car enthusiast like us, but he can read the wiring diagrams way better than i. we concluded from a bunch of tests and more than a few hours testing and cracking jokes on the phone that the ecm is fried, it kind of works but not sending power to main relay. he says he never worked on a subaru but their wiring is pretty straighforward from the diagrams, he is a big gm guy and says some of their duramax wiring is much more needlessly complicated. he mostly gets gm, toyotas, fords, vw cars and trucks up there. funny he never got subaru, he is in colombia county and it is really rural with harsher winters than we get here in nyc, but it is true i didn't see many subarus there, mostly ford and gm trucks

i never changed an ecm on any car before, luckily i don't get too many electrical problems i guess. closest ecm change i ever did was a chip that controlled bosch fuel injection in an 1983 audi 5000, that was ridiculously easy, just disconnected battery and installed it. it was a small chip half the size of a full palm.

my question now is if i get a used, or new ecm, and change it, is there any security programming, relearning procedure, or initiation sequence to get it to work on my car?

if you know about this or have done it before please let me know.
 

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i was lucky jim's business was slow today and he had time to help. coronavirus scare and the fact that he says things are usually slow at work this time of year.
 

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Blowing an ECM is pretty rare.
I've only heard of having to get one replaced a half dozen times or so in decades.
It happens but it is also a potentially expensive repair. What bothers me is that it is a 'black box'. One never has direct evidence that it broke directly - you eliminate all the stuff it is connected to, power ground, signals, etc first.
So I'd make absolutely sure that all connections are made to the ECM before you even consider replacing it.

Just follow my logic as I'm thinking out loud here:

So you're absolutely sure the key works?
Your key does have a chip in it that's interrogated by the computer. There's an antenna in the steering wheel's keylock assembly that wirelessly talks to your key to make sure it belongs to you car.
I'm not sure whether that debug connector test needs to have the ECM see the right key but it does need to see a key to turn the power on.
I am pretty sure OBD2 is supposed to operate without that key security passing. After all, that's how they program new keys into the unit.
So it likely isn't that key/chip. Again, thinking out loud here.

So if it has proper power, ground and ACC, that ECM is supposed to at least talk OBD2. With the key on (whether it needs to see the proper key's chip or not we don't know) should let you let the computer cycle through its debug test with those green connectors plugged together.
It does not do either so the ECM may very well be bad.

That leads me to a next quesion:
Did something happen to your car? Was it flooded with the sunroof open? Was the battery in backwards? (Eventho, that may not blow the ECM - my son in law did it all that did was blow the main fuse).
I'd make sure that whatever blew that ECM is not going to take out a new one. I'd want to know the mode of failure of that unit so it doesn't happen again.

Ok, now as to replacing that unit:
There are several used car parts places in the area. Shipping may be cheaper but who knows how long things take nowadays. I ordered a NAS server two days ago that won't get here until late April. My point is that shipping time is changing - so you may need to pick it up.
I've dealt with the following places many times and highly recommend them. They are very organized, professional and may very well have what you need. Their prices and quality is good. They don't jerk you around:
Chuck and Eddie's autoparts in Meriden, CT. They have a place in New Haven as well. They are fantastic.
Tom's Foreign Auto Parts in Waterbury CT. Great place.

I'm pretty sure the VIN, features and keys need to be programmed into the ECM. Dealers may tell you that they can't do it on a used unit. I think they don't want to because it precludes them from selling you a new ECM.
There are places that clone/reprogram ECMs for a price. I have a two way OBD2 tool but I don't think I can reprogram VIN and features on Subaru. I can program keys.
You're my area and there are subaru tuners out there (NY, CT, NJ). They can definitely do it. Let me look around..

Sorry for the longwindedness but that^ may be what you need to deal with.
 

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Discussion Starter #10
Rem thanks, this car has no chip in the key at all, just a metal key i have made copies of, and they all work fine,
i would like to know is there any programing or security learning process involved to get this to start and run in my car?
so i would have to clone a used/new ecm to my car?
what i mean is can i just install this ecm in place of my old ecm and start right up without anything else?
last night after i replied to you on this post i found some on ebay used 39-70 bucks, they asked for my vin #, does that mean they clone it or just verify if i could use it?.
this computer problem is all new to me.

thank you
Ron
 

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@Rongonza That's likely what they'll do, yes. I'd ask. The VIN tells them what options it is supposed to have. I'm sure it isn't a super sophisticated thing to do, this "programming", but you need a special tool for it. They may have that ability.
It could also be that they just want to verify it indeed works for your car. That's good diligence on their part but if they can program it, even better. So do ask.

If so, it likely is a plug and play situation. Once the car starts, it needs to learn its throttle position. It does that by it sitting in idle for about 10 minutes, without you doing anything but watch.

Hopefully that's it and you're well on your way after this..


... well, you're home with the rest of us, but you know what I meant. :)
 

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Rem thanks, just read this, i havent been online until late tonight, had family stuff going on past few days.
i emailed a company on saturday and a rep. called me today saying they were in chicago and due to corona virus they can't order or send any new orders until late april.
the guy was nice and explained to me that 90% of the time if subaru ecm has the same number on the outside sticker it is plug and play and needs no programming. only needs programming if it has been altered from dealer specs, which most haven't been.
he said from sticker on mine, the car is california emmisions and they sell it used for 290 bucks.
funny because according to car paperwork from last owner i found in my car, it was originally bought from a dealer in maine in 2007, but the computer is a california emmission ecm.

i found one on ebay used a little while ago for 41 bucks, with same numbers and stickers as on mine.
i asked seller if he knows if it will work and if there is a return policy, when he responds i think i will try that one out.
 

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by the way thanks for all your help. i wasn't on this site much lately, but the 41 buck computer i bought worked well without any programming. i spoke to a dealer service dept. they said it didnt need reprogramming and they were right. it was just plug and play, and car started right up.

also the dealer service guy said i was lucky, the older subarus like mine were better than the new ones they have.
 
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