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Old 09-25-2017, 11:03 PM   #1
MaineHawkeye
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Member#: 475134
Join Date: Sep 2017
Vehicle:
2007 Impreza Wagon
Crystal Gray Metallic

Default Wiring or Electrical Problem

Have some problems and I need your help.

I have a 2007 Impreza 2.5i Wagon with 29,000 miles. Purchased it this past winter. It had been hit in the front. Had to replace all the front body parts, including radiator core support, radiator, a/c condenser, power steering pump, power steering reservoir, electronic portion of the ABS pump, etc.

I had a 2006 OBS donor car already that I was getting ready to sell or part out so it made this a cost effective project.

Got the car put back together and it runs great!

But...Every possible light is on:

-Cruise light is blinking
-Check Engine light is solid
-ABS light is solid
-AT Oil Temp light is blinking fast

I brought the car to a local "Subaru" shop and the owner used a Subaru Select Monitor to check all the codes.

The codes were:

ECM:
-P0700
-P0028

TCM:
-P1778

ABS:
-25
-27
-47

He believes that the car has a CAN / BUS Circuit problem. He believes that there is a problem in the wiring itself, and not in the individual components that are associated with the codes.

He cleared all the codes and they returned immediately.

From what I can see, none of the wiring was damaged from the accident.

What am I missing? Has anyone come across this before?

The car runs great. Where do I start?

Thanks for reading!
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Last edited by MaineHawkeye; 09-25-2017 at 11:47 PM.
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Old 09-27-2017, 08:31 AM   #2
Elbert Bass
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Electrical issue requires diagnosis - no magic guess unless you see physical damage to wiring or connectors. Gotta run to fix Subys for money but here is a quick rundown on your codes.

P0700 - The TCM is asking for help from you.

P0028 - left bank variable valve lift control circuit (left front cylinder head)

P1778 - not a valid code for 2007 Impreza 2.5i

Airbag 25 - fuse 6 in box under hood blown, faulty ABS wiring, faulty ABS module.

Airbag 27 - fault in Occupant Detection System (passenger seat) faulty wiring for ODS, faulty ODS module, faulty ABS module.

Airbag 47 - not a valid code for 2007 Impreza 2.5i

Did you write those invalid codes wrong?
Probably not CAN bus problem - you would have a list of codes twice as long and a bunch of communication codes.
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Old 09-27-2017, 10:24 PM   #3
MaineHawkeye
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Crystal Gray Metallic

Default

Thanks so much for taking the time to respond!

The codes were written down by the shop owner and I am having trouble reading what he wrote.

I initially borrowed a fairly nice Autel scanner and was able to retrieve all the codes, but assumed that I could not clear them because I did not have a Subaru Select Monitor.

I will pull the codes again myself and reply back with the correct ones.

Thanks again!
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Old 09-28-2017, 08:22 AM   #4
Elbert Bass
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Quote:
Originally Posted by MaineHawkeye View Post
Thanks so much for taking the time to respond!

The codes were written down by the shop owner and I am having trouble reading what he wrote.

I initially borrowed a fairly nice Autel scanner and was able to retrieve all the codes, but assumed that I could not clear them because I did not have a Subaru Select Monitor.

I will pull the codes again myself and reply back with the correct ones.

Thanks again!
I forgot to ask - did any of the airbags inflate?
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Old 09-28-2017, 12:27 PM   #5
Charlie-III
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Silver Sleeper BK, 5MT

Default

Quote:
Originally Posted by Elbert Bass View Post
I forgot to ask - did any of the airbags inflate?
With the damage listed in post 1, I have to assume so....unless the car was parked and key off.

Let me guess, you think the airbag controllers need to be replaced if airbags went off?
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Old 09-28-2017, 09:35 PM   #6
Elbert Bass
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Quote:
Originally Posted by Charlie-III View Post
With the damage listed in post 1, I have to assume so....unless the car was parked and key off.

Let me guess, you think the airbag controllers need to be replaced if airbags went off?
You ALWAYS have to replace the SRS module if air bags have been deployed. In fact I have seen them fail (and fail the ODS module) just from charging up during an accident that did not require inflation but were strong enough to require arming.
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Old 09-28-2017, 09:52 PM   #7
MaineHawkeye
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2007 Impreza Wagon
Crystal Gray Metallic

Default

Ok, I used an Autel Maxidas DS708 scanner.

It pulled up:


OBD:

-P0700 (transmission control system)



Transmission Control System:

-P1718 (at can communication circuit)



Engine Control System:

-48B7 (It said it was a propriety code and to refer to the factory repair
manual)



Brake Control System:

-27 (rear left abs sensor circuit open or shorted battery)
-47 (improper can communication)
-25 (rear right abs sensor circuit open or shorted battery)

The car was titled as a 2007, however the manufacturer date is 08/06 which seems a bit early to be a 2007?

I purchased the car from somebody who purchased it from Insurance Auto Auctions. When I received the car, there was no evidence that the airbags had gone off. The previous owner sold me the car for what he paid at auction. He supplied me with his invoice from IAAI. He needed the $ and from what he told me he had not done any repairs to the car.

A couple of additional points:

The ECU on the ABS Pump got hit as well as the Power Steering Reservoir, which from what I see is common on these year Impreza's that get in front-end collisions. We have two 2006 Impreza's that were salvage vehicles and had already been repaired when we purchased them. Both of their ABS Pumps had ECU's that had been hit and repaired with epoxy.

The ABS ECU on this 2007 had damage to the actual electronics, not just the plastic housing from the hit and also had gotten power steering fluid and water in it. I found a low mileage ABS Pump and swapped out the ECU.

Also, the transmission pan does have a dent in it. Not sure if it is from the accident, when it was towed, or previous damage prior to the accident.

The transmission does shift a bit firmer at times, but not always. The fluid is full when hot, nice and red, and smells good.

I also checked both rear ABS sensors which appear to be ok, along with both rear tone rings.

Last that I can think of for now is that when I first got the car, I noticed that one of the engine ground wires that mounts on the driver side of the engine, towards the rear, somewhat near the starter, was disconnected. I thought that was odd.

Anyway, thanks again! I hope this additional info makes sense.
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Old 09-30-2017, 12:02 PM   #8
Elbert Bass
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Default

Quote:
Originally Posted by MaineHawkeye View Post
Ok, I used an Autel Maxidas DS708 scanner.

It pulled up:


OBD:

-P0700 (transmission control system)



Transmission Control System:

-P1718 (at can communication circuit)



Engine Control System:

-48B7 (It said it was a propriety code and to refer to the factory repair
manual)



Brake Control System:

-27 (rear left abs sensor circuit open or shorted battery)
-47 (improper can communication)
-25 (rear right abs sensor circuit open or shorted battery)

The car was titled as a 2007, however the manufacturer date is 08/06 which seems a bit early to be a 2007?

I purchased the car from somebody who purchased it from Insurance Auto Auctions. When I received the car, there was no evidence that the airbags had gone off. The previous owner sold me the car for what he paid at auction. He supplied me with his invoice from IAAI. He needed the $ and from what he told me he had not done any repairs to the car.

A couple of additional points:

The ECU on the ABS Pump got hit as well as the Power Steering Reservoir, which from what I see is common on these year Impreza's that get in front-end collisions. We have two 2006 Impreza's that were salvage vehicles and had already been repaired when we purchased them. Both of their ABS Pumps had ECU's that had been hit and repaired with epoxy.

The ABS ECU on this 2007 had damage to the actual electronics, not just the plastic housing from the hit and also had gotten power steering fluid and water in it. I found a low mileage ABS Pump and swapped out the ECU.

Also, the transmission pan does have a dent in it. Not sure if it is from the accident, when it was towed, or previous damage prior to the accident.

The transmission does shift a bit firmer at times, but not always. The fluid is full when hot, nice and red, and smells good.

I also checked both rear ABS sensors which appear to be ok, along with both rear tone rings.

Last that I can think of for now is that when I first got the car, I noticed that one of the engine ground wires that mounts on the driver side of the engine, towards the rear, somewhat near the starter, was disconnected. I thought that was odd.

Anyway, thanks again! I hope this additional info makes sense.
Oops! I misread your original post - Those were ABS codes not Airbag codes. Plus looks like you have some additional codes...

P1718 is a problem with the CAN bus between ABS, TCM (transmission control module) and ECM (engine control module). The diagnostic is to unplug those 3 modules and perform continuity and short tests on the 2 CAN bus wires between those modules. If the ABS harness was damaged when the ABS unit got damaged I would physically inspect to see if any wires are cut or got crushed and shorted together.

The 48B7 is a sub-code. Some codes have additional identifiers that narrow down the problem. Without the prime code you really can't diagnose. It is not related to any of the other codes you listed.

Those 3 ABS codes could be result of wiring damage as noted above. Code 47 goes hand-in-hand with the P1718. Depending on the type of wiring damage (particularly shorts to other wires, ground, or power) it can damage a replacement module and still cause codes if the wiring issues are still present when you replace a module.

New model years traditional start manufacture in August of the previous year so an 08/2006 would be a 2007 model.

Transmission performance will be affected by that communication code - I wouldn't evaluate transmission performance until after repairing the fault causing the codes.
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Old 09-30-2017, 09:40 PM   #9
MaineHawkeye
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Vehicle:
2007 Impreza Wagon
Crystal Gray Metallic

Default

I still have the donor car and looked at the routing of the ABS harness. Looks like it routes behind the passenger side fender/fender lining and then into the passenger compartment.

That fender was also damaged, so I will inspect the harness. I also noticed that part of the harness is painted the same color as the car, which we know Subaru does not do. Even with its low mileage, I wonder if the car had a fender bender previously. The harness could have been damaged even before the car was totaled.

Any idea if the ABS harness is the same on the 2006 Impreza OBS donor car I used and the 2007 I repaired? They are both Auto. I was thinking about "overlaying" them as a quicker way of identifying the problem.

Also, how can I identify the 2 CAN bus wires that run between all 3 modules?

Thank you again for your time and expertise!
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Old 10-01-2017, 01:05 AM   #10
CosmoTheCat
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2002 Imprezas were IN showrooms in what, 3/2001? You cannot rely on a build date to determine model year.

Everything is pointing at the ABS module or wiring, did you inspect the bulkhead harness for damage inside the fender?

Is the new ABS module correct for the vehicle? I don't remember what year they started doing it, but does it need to be configured? Have the build code entered?
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