Ecu problem?

[Tommio RS]

Hi there. I recently got myself another legacy turbo with a minor little problem.
The last owner of the car had an alternator installed by a "friend" and some how put the wires on backwards to the alternator and "Popped" the ecu when they turn the key...

I switched the wires at the alternator to the right way and still nothing....

I think the ecu is toasted.

Here is why i think it is toasted:

Turn the car to the "on" position on the key and some of the idiot lights dont light up. IE the engine light
Try to crack the car over and just like a dead battery everything just goes flat dead. So that is ok.
Everything else works great! Like electrical stuffs.


Things i have done:

Check all fuses.
Checked for melted wires
Pulled out "blown" ecu and inspect for shorted parts. That came up negative.
Made sure alternator wiring is correct.

I was thinking i could use the ecu out of my 93 ss, BUT incase there is something really dam wrong im not going to fry another ecu just for test purposes and have 2 dead legacy's.

Any ideas would be great.

[Redlined]

My kid just did something similar with his Zoom zoom Mazda save he shorted a wrench across the power leads to the starter with the key on in the ignition. with much the same results. I think as long as you have visually inspected the wiring, fuses, etc. you should be safe.

Have you checked the fuse panel under the dash AND the one in the Engine compartment? Does the engine turn over at all? if it doesn't the starter connections may be damaged/tac'd.

Just kinda brain storming. and tossing out ideas.

[Tommio RS]

The car will not crank,make a fuel pump sound nothing....

I check every fuse under the dash and the hood and they all seem fine. I could pull out all of them and check them manually.

Tho your post joggled my mind about something.
Could i have a burnt out ignition relay??

Because if the alternator was wired backwards it could have cooked the coils in the relay? Maybe??


So ya. Ill make a situation for ya people.

Sitting in the car with the key on the "ON" position
Radio, fans, door lock, lights, auto tranny shift lights and some dumby lights and the dash. NO check engine light.
Turn key to "Start" position
You know that brief moment when your car is starting up everything is off and not running when it really is?
Its does that for aslong as i hold down the key.


So im at a fork in the road.

[cj91legss]

Ok, so you're afraid to take the ECU out of your other SS and put it in this car you're having problems with... Totally understandable, BUT what about if you took the ecu out of your (Lets say) Problem car and put it in your Good Running SS????

Then you could determine if the ECU in your problem car is indefinately done...

[Tommio RS]

cj91legss! Yor my friend are a friggen genius!!!

Give me the dumb @$$ of the year award!
Im going to do that this morning!

Why did i not think of that!

Thanks cj91legss!!

[cj91legss]

I try

[Tommio RS]

Ok. So i tried out this "Blown" ecu out in my good legacy....

IT WORKS!!

So now this leads me into a new direction. I need to figure out why the ecu is not getting power anymore.

[Legacy777]

I'd strongly suggest pulling out each individual SBF and the fusible link in the engine compartment and test them with a multi-meter. One of those is likely fried.

[Tommio RS]

An update...

So ya i will give you a run down off what i have all done.


Changed the ignition relay.
Checked the fuses every where.
Checked the fuel pump relay
Checked the igniter. And there was not power there?
Checked the ecu.
Checked the tcu...kinda
Removed the MPI immobilizer for insurance.


The car doesnt have a engine light or a power mod light. That is when the key is on the "ON" position.
The car will crank and crank and crank, and get no fuel and not spark at the plugs.

So i saying that Legacy777 im going to do a full check of all dam fuses by pulling them out and manually checking them. Other than that... I really dunno what can be wrong.

Any ideas??

[Legacy777]

You said "Checked the fuses every where."

How did you check the fuses since you said later in the post that you are going to do a full check by pulling them?

If the Check Engine or Power light does not come on with the key in the ON position then the ECU/TCU are not turning on. Verify that the ECU & TCU grounds are good. MB-3 is what appears to be supplying power to the ECU through the ignition relay.

So from the battery, you've got SBF-2 to MB-3 to the ignition relay. So definitely check those and the wiring.

These diagrams may help.

http://www.surrealmirage.com/subaru/fil ... arting.jpg
http://www.surrealmirage.com/subaru/fil ... uting1.jpg
http://www.surrealmirage.com/subaru/fil ... uting2.jpg
http://www.surrealmirage.com/subaru/fil ... rical1.jpg

[Tommio RS]

Thanks Legacy777 your diagrams helped me out for sures!

Ok i found the problem!

Here is what i did to make this car run.

The MPI Immobilizer was right fired!
Aswell the fuse for the ecu and tcu was shorted.

So basicly the alternator wiring was backwards sending power into the fuse and immobilizer killing them both in one shot. I changed the fuse and the car still didnt start.... >Then i hurt and little ticking sound, like a relay on the way out. Thats when i figured out the immobilizer was toast.


So Your thinking now...

What the hell is an MPI Immobilizer? Well MPI= Manitoba Public insurance and its there immobilizer. Every Subaru under the years 2004 and down needs one in my province. It will cut power from the ignition relay,Fuel pump, ECU,TCU,etc. Basicly everything but the starter system.

Now after all the bull crap i have a cheapo leggy turbo to drive!!

[cj91legss]

Do you Absolutely have to have it? i'd rip that crap out!!!

[Falken-18c]

i think i seen that car on kijiji u bought it that way right

[Legacy777]

Glad you figured out the problem.

[Tommio RS]

Falken-18c. Yes i got from kijiji that way. I know that the ecu was not fried from the start. I have NEVER hurd of a blown ecu from that situation of problems.

cj91legss. Yes you "Have" to have it in your car...Its the only way you can have it insured in my province....Tho just insure it and rip it out. Aslong as there system of computers knows you got it once. They will not know that your "Dont" got in anymore. If you know what im saying.