ECM problems

[Jlarwood]

I have a 95 legacy with a 2.2. It started dying intermittently and then starting right back up again no check engine lights. My first thought was the fuel pump was bad so I replaced it and the fuel pump relay. It didn't fix a thing. I then proceeded to check the resistance on all the sensors and they all checked out good. I finally admitted defeat and sent it to a local repair shop something I really hate doing. When I got it back they claimed that it was the ecm + bad cam and crank sensors. They said they could install new ones for $1200 I was shocked and appalled I know they just plug in, so I paid for the diagnostics and got my car the hell out of there. I ordered an ecm off ebay from a salvage yard same exact numbers and same year and new cam and crank sensors. Put the new stuff in and now it won't crank at all I can put the old ecm back in and it still won't start no check engine light when it turn the key on I hooked a scanner up to it and it said it could not communicate with the ecm. Do I need to flash it? Can they go blank when you switch them out? Any insite into this would be greatly appreciated. I just don't know what to do with it.

[Fairtax4me]

Did you disconnect the battery before unplugging the ECU?

 

Is it plugged in all the way and the lock latch flipped to the lock position?

 

Have you checked all of the fuses?

 

 

Original stalling problem is probably the MAF sensor. Pretty common on the mid 90s years.

Edited April 18, 2016 by Fairtax4me

[Bushwick]

Check your fusible link in the engine compartment fuse box. It's a short " U " section that jumps a connection with spade lugs. Mine originally cracked on the bend and the silicone split, allowing moisture in. Over time, it built up corrosion and broke the connection. It scorched the underside of the cover slightly. 

 

In an emergency, you can jump it with a heavier gauge wire and it'll start. Engine won't crank if the connection is broken, and I think some dash lights will fail to light. When turning the key, half the car won't respond. 

 

I replaced mine with a generic fusible link from AZ, but had to go one step thicker as the replacement got too warm on engine idle. If you have a pick set and needle nose pliers, you can reuse the factory spade lugs as those are very high quality stainless. Do NOT use cheap speaker wire lugs as the metal is inferior.

 

Also, this jumper can cause intermittent start/no start issues if enough of the wire is touching at the break, but it WILL arc and burn the wire out.

[Jlarwood]

I diconnected the battery when I switched them out.No fuses are blown. I will take a look at the fusible link. If it was shorting out wouldn't all of the dash lights not come on as well?

Edited April 18, 2016 by Jlarwood

[wtdash]

Hi,

Did you verify that the ECU connector is latched?

 

There is NO flashing of the ECU / ECM needed....in fact, I've never heard/read that the '96-'99 years could even be flashed.

 

I'd return everything back the way you had it (ensure your battery is charged), and try it.

 

As noted above, Most likely it's the MAF causing your original issue. '92-'98 Subaru Impreza, Legacy (non-turbo), Forester EJ22 and EJ25 all used a green label MAF: 22680AA160 or 22680AA160F 

 

i'd try another used one...due to their cost new.  $300+ from dealer.

Edited April 18, 2016 by wtdash

[Jlarwood]

Yes the ecu connector is latched. I just find it strange that it was running before I switched them then it would turn over but never start even when I put the old one back in I followed all of the procedures when I switched them and now a scanner can't even detect the ecm.

[Fairtax4me]

Make sure none of the pins in the ECU are bent.

Also make sure none of the pins have pushed out of the harness connector.

 

Beyond that, you may want to check to make sure the ECU is getting power. You'll want a service manual for 95 for the pinout and wire diagram to check that.

[mikaleda]

Check you grounds and power to the ecu.

[Jlarwood]

I will take a closer look at the pins. Does anyone have the pinout diagram for the 95 legacy. I have tried seaching the internet but came up with a bunch of useless stuff. My Haynes manuel doesn't even have it.

[wtdash]

See attached. It has most Subaru's.

 

The USA '95 Legacy models all used the same engine, so don't get hung-up on the 'Legacy Outback' listing.

Edited April 20, 2016 by wtdash

[Jlarwood]

For some reason when I opened the attachment it was blank.Do you have to use a pc to view it?

Edited April 20, 2016 by Jlarwood

[wtdash]

For some reason when I opened the attachment it was blank.Do you have to use a pc to view it?

No idea...but I was able to view it on my iphone. Try this: jdmfsm.info/Auto/Japan/Subaru/

Edited April 20, 2016 by wtdash

[Jlarwood]

that one worked I am hoping to take a look at the grounds soon been real busy lately I'll post what I find. Thanks for the help.

Edited April 26, 2016 by Jlarwood

[Cougar]

I don't think you have a ground problem. From what you stated about the issue you seem to have a problem on the power side of the circuit (like Fairtax4me stated also). It appears power isn't getting to the ECU and data connector which fuse SBF-2 provides power to. Fuse SBF-2 is in the panel under the hood and is tied to a two pin connector with red and blk/wht wires. Verify the connector is making good connection to the fuse panel and that the red wire has 12 volts on it while the ignition is ON. If that is okay then you will have to follow that wire to the next connection and check for power after it until you find the bad connection. Once power is restored the ECU light and other things should work ok. If you want to prove a connection to ground is okay you can run a temporary ground jumper between the suspected bad point and a good known ground point. If things then work then the working ground connection is bad and needs to be fixed. You can also check for a voltage drop on the suspected ground. If there is a connection problem you will see voltage on the ground when using a good ground point as your meter reference point.

[idosubaru]

I would also verify all the work you've done - get it back to original ECU and sensors and make sure they're all connected/nothing damaged. 

 

SUbaru ECU's don't typically fail outside of some significant cause - so that's likely an incorrect diagnosis. 

 

any time a shop says to replace three separate items you have to wonder: 
1.  three things all decided to fail at the same time, a probability of probably 1 in BILLIONS.  bad luck on you. 

2.  the diagnosis was incorrect. 

 

normally it's #2. 

 

i'd start over, go back to the original stuff and verify every single connection you've worked on since it last started to make sure something isn't disconnected, wrong, or damaged. 

 

when somethign worked - was worked on - and then doesn't - there's always a strong possibility that something was compromised in the work rather than some unknown.