ECU-Frequent Failures

I have a 1996 SVX with a little over 61000 miles, very-well cared for. Starting with a check-engine-light failure after 3-1/2 years, the Subaru dealer has replaced the ECU 8 times and has the 9th replacement on order (the most recent unit endured for 17 miles, a new record)! In every instance, they have been unable to pull the trouble code from the computer. I am told that they and all levels of Subaru (including those at Fuji) have tried or considered everything and have no idea what is causing the problem. They believe that something is shorting-out the ECUs. Almost 3 years ago, they replaced all 3 wiring harnesses and the alternator (which was spiking, apparently). All to no avail. Except for the alternator and a new battery, all this has been at no expense to me, thankfully.

The car's operation has not been affected, at least not until recently: I have some skipping during idle, especially until the car has run for quite a while, after which it smooths-out (relatively speaking). They claim that is related to the computer failure; however, I am not sure about that because it has never happened before and continued during recent brief stretches when the check-engine-light extinguished for a couple of days. All the plugs were replaced by them a little over 1000 miles ago.

By the way, the light has gone off 5 different times during the 2 months since the last failure, always at start-up, and remains off for varying lengths of time and mileage - none very long.

The dealer says that Subaru has never experienced this kind of failure and is now apparently content to continue to replace the ECUs. I have periodically searched SVX chat sites and although there are many check-engine-light stories and solutions (usually involving the oxygen sensor), I have never found one such as mine.

[Mr. Pockets]

Nor will you, I would wager. That's completely bizarre. Replacing all the wiring looms must have been quite the tedious job for them.

When you say that Subaru is content to continue to replace ECUs, do you know how long they're willing to do this?

If you've replaced 8 of them, then I guess you're going through about one a year, huh? What the heck could cause such an intermittent problem, I wonder...

Is there a chance you could talk to another dealer and have them look at it? I know my local dealer is so bad at reading wiring diagrams that they thought they blew $700 of components on my wife's car (and were planning on charging me for the pleasure) before they figured out that they had simply blown another fuse.

[svx_commuter]

Wow This is quite a story you have. :|
Since they replaced the wiring harnesses it still blows out. Well that says it's not a short in the wiring. I am thinking it may be a short in a sensor, coolant, tps, MAF, O2 has my bet. That has a voltage supply to the sensor.

The next time you get a new ECU you might try disconnecting the sensors and pluging them in one at a time or checking the resistance and ground condition of all the sensors before it gets plugged.

I think we are all interested to know how this turns out and what the cause is. I know I am.

Any recourse with the Lemon Law?

Are you also saying that your SVX runs with a failed ECU?

If you want to send me your name I would happy to fire off a letter to SOA, on your behalf, as a fellow SVX owner, and tell them to fix your problem. It really appears that SOA does not care.

Thanks for the quick responses. Actually, the ECUs didn't begin to fail until the car was about 3-1/2 years old, so the failure frequency is even higher than 1/yr; also, some of the longer elapsed times between failures are due to long delays in obtaining replacements.

Yes, the car has continued to run without problems (except for the possibly related recent skipping at idle I mentioned).

As for my experimenting with sensors or the like, although I am reasonably skilled with many manual tasks, I am essentially incompetent relative to automotive repairs! And I don't want to give the dealer an excuse to not honor the warranty.

I hesitate to go to another dealer. These folks have treated me very well (we have a Legacy wagon, too) and have charged me for nothing except as I mentioned. it appears they will replace ECUs without argument or charge until the 80,000/8 year fed emissions warranty expires May 31. I am looking for ideas that I might "suggest" to them. I think I will mention the sensor testing idea when they finally replace the current ECU.

[CDG]

May I suggest you take this aprticular SVX to the dealer and trade it in on a new WRX or whatever turns you on.
Please post the serial number for us so one of us doesn't get stuck with it.

I'm sure you love the car as much as we do, but you need to be realistic.
If SOA has not resolved the problem before warrantee runs out, then they are still responsible. But they will put up a fight, so get a respectable $$$ for it as a trade in and move on. Then take your tax refund $$$ and buy another used one with some good history.

There will always be those vehicles with anomolies that cannot be found. Perhaps some-one may find the issue, but if your deadline is this may, don't get your hopes up.

my 2 cents worth.

As Commuter says, perhaps SOA will provide you with an Option, but work with your dealer on that. Your relationship with your dealer sounds precious.

[Ron Mummert]

First of all, welcome to the flock.
I'm probably the last person here you'd want to offer up a cure, but you say for 3 plus years the ECU DIDN'T fail, then began to regularly perplex Suby's best & brightest. Was any other work done to the car around the time of the first failure? If a short's involved, something's doing the shorting that wasn't installed at the factory.
Even the best surgeon occasionally leaves a sponge inside the patient.

Ron (perfecting the SWAG method).

Here is the latest:

The dealer replaced the ECU and the check engine light went out - but only for a few miles! Those few miles straddled several weeks of inactivity while I was away.

After the light reappeared, I checked this site again to see if there is anything new on the subject, in general. Someone said that pulling the #14 fuse would reset the ECU. So, I checked the fuse boxes and found that the 10 amp fuse (in the engine compartment box) for the "FWD" is missing as is the spare 10 amp fuse. How long this has existed, I have no idea, and the only people who have been under the hood doing work have been the dealer's mechanics.

I am ignorant about modern auto mechanics/electronics but the implications of this to me are:
• the FWD circuit has a fault; the mechanic found the blown fuse, replaced it and then pulled it without replacement after the spare also failed.
• I have been without FWD, unknowingly, for who knows how long!
• Might there be a relationship between the apparently faulty FWD circuit and the failed ECUs?

As for the #14 fuse, pulling it had no affect on the check engine light. when I did so, the ignition was off. Should I have the ignition on when pulling the fuse to trigger the reset? Again, please forgive my ignorance.

Of course, I intend to return to the dealer (they have already obtained the replacement ECU) but before I confront them about the fuse, I want to get as much info as I can.

Thanks for any help you guys/gals can provide.

[svx_commuter]

If the CE light stays then there is a problem. I suggest you take your car to an AutoZone and have them read the ECU. They do this for free and can tell you why the light is on. The 1996 is OBDII right? You have a computer connector in the dash to the right of the steering column?

Yes, I believe it is OBDII and yes, the connector is where you say; however, as for trying Autozone, the dealer has said that they have been unable to pull the codes from the ECUs. This has been true, they say, for EVERY time the check engine light has appeared. I doubt that they would lie about this - it would have been easier for them to identify the problem a long time ago, I assume.

[Aredubjay]

First, let me add my welcome, as well as my puzzlement for your anomoly.

There should be NO fuse in the FWD position, UNLESS you want to put your car into FWD (FRONT WHEEL DRIVE) mode. Putting a fuse IN, disengages the rear drive and makes your car FWD, so, that's not your problem.

Whew - thanks!

[Aredubjay]

Originally posted by subavexed
Yes, I believe it is OBDII and yes, the connector is where you say; however, as for trying Autozone, the dealer has said that they have been unable to pull the codes from the ECUs. This has been true, they say, for EVERY time the check engine light has appeared. I doubt that they would lie about this - it would have been easier for them to identify the problem a long time ago, I assume.

If Autozone does it for free, then, what have you got to lose? Granted, they would want to find the problem ASAP through use of their equipment, but, I find it EXTREMELY disconcerting that, if EVERY time they hook up your car they cannot pull the codes (with a KNOWN GOOD ECU in place), then, there is A) A problem in the test circuit, B) A problem with their equipment. Go to A/Z for sh!ts and giggles. You may (or may not) be surprised, but, for "Free" you can't beat the price and you "may" get confirmation of a fault in the test circuit. It's different equipment, so, it would, at least give you (or, would me anyway) peace of mind that the dealer's equipment isn't faulty.

Thanks again - I will try them, after all (just for ****s and giggles)!

[Aredubjay]

Originally posted by subavexed
Thanks again - I will try them, after all (just for ****s and giggles)!

THAT'S the spirit!

Huzzah (I hope)! I have just returned from AutoZone where they successfully accessed the ECU and pulled the code P0302 - "cylinder 2 misfire detected." They also cleared the CE light but advised that it might return. They said it is probably the sparkplug coil or boot.

Next step - back to the dealer (they replaced the plugs about 1600 miles ago).

Thank you, thank you, thank you!