VDC + flashy brake - bluedriver codes

[peril]

Hi all - just did struts and after alignment car was clean - 24 hours and then threw the following [1]VDC codes. In diagnosing - did find (2) dead brake lights - fixed those, attempted to clear codes but came right back - also tried a 30 min battery / module reset (will try that again too). 

 

Any other ideas, the bluedriver is good for obvious codes, but seems like a specialty tool (better obd dongle  / hw  with subaru systems checks might be in order.)

I did 

-brake lights (2 x 7443)

-battery disconnect 30 minutes

Thinking about

-brake switch

-electrical short (but not sure where vdc / abs modules are - googling)

 

[snip [1]]

VDC/ABS

U0141

C1040

C0071

C0074

C0042

 

Edited June 18, 2023 by peril

[DrD123]

C0042 is a power supply failure, C0071 is no signal from the steering angle sensor or the steering angle sensor is inoperative, and C0074 is an issue with the master cylinder pressure sensor output.  I don't know if the other two are valid 5th gen OBD codes - certainly not in the service manuals that I can find.  Googling, C1040 could be a wheel speed sensor issue and U0141 could be a loss of contact with the instrument panel.  

If it was fine before you changed the struts and got it aligned, my thought would be to get under the car and look at the wiring harnesses/connectors near the front struts/wheels, as well as near any of the alignment adjustment paths - maybe there's a short, broken wire, or unplugged connector somewhere.

[peril]

Well - I did find the vdc harness - and did a quick check in my outback (2013 with eyesight) - I pulled the VDC harness - started the car, to see what happened (and if clearing it was pretty straighforward). 

Pulling that harness does a LOT, AT, ABS, brake, VDC, and eyesight all light up very angry - reseated the harness, cleared codes, reread and there were a couple of permanent codes from that little experiment -but not a big deal. 

Anyhow - everything cleared up after a read / clear with the bluedriver; I'm gonna try the same game in the legacy and see how it compares. I did an inspection on the vdc, and that looks pretty clean; will pull the harness and poke around and make sure the basics check out (voltages, ground, resistance) across a random set. (I'm really really hopeful something obvious comes up - like a ground, or voltage out of spec.)

(On the plus side - I learned quite a lot today on the vdc, and how it connects to the abs / and wheel speed / brake sensors - so I got that going for me ) 

 

Edited June 19, 2023 by peril

[peril]

And not to ignore you advice, will get the car up in the air on Tuesday and check all of the sensors around the tie rods / struts; and really look; also see the value of having a real obd scan tool that can read these systems live and do all of this diag for me so im not doing it old school with a multimeter at a harness.

I'm in the middle of a (2) full front / back suspension gig - did both fronts and rears on my sons 2013 outback, and daughters 2010 legacy; also did a wheel bearing on the 2013 - so I've been busy over the past weekends.

[DrD123]

Depending on which one has the issue, there are some networky changes going from 2010-2012 to 2013-2014 - Subaru gangs the grounds together at joint connectors in the harness, so if there's one in the systems you are looking at, that's worth chasing down too - I could easily see how an intermittent power supply (supposing a connection was being made/broken) could get all sorts of stuff mad and maybe mess with the CAN.  Scan tools are great, but they tell you more or less what the car thinks is wrong (a bidirectional tool would be something else - I haven't been inspired to get one just yet - I use something similar to you for most stuff - an OBDLink MX+ - I also keep a cheap ELM327 emulator in the car just in case I need it while out and about) - never underestimate the usefulness of a multimeter and a test light for chasing electrical gremlins.  (nowadays, watching some of the repair videos, an oscilloscope can be useful, too)

[peril]

The problem is in the 2010 legacy - which is pretty garden variety - the 2013 outback is "the good one" for now. just useful to be able to compare back and forth for diagram. 

The problem is only on the legacy (for now).

 

 

[m sprank]

Dont worry so much about a code reader.  Everything points towards an issue from the strut replacement.  You probably dorked an ABS wheel sensor or some wiring.  You performed physical work and then codes popped up related to the area you were working.  Start visually/physically inspecting and stop wasting time with scanners.  Scanners come out after you verify everything else as this is NOT random.   

[peril]

++ don't disagree - I'm interested in seeing what is working and not without having to pin out each sensor. 

Edited June 20, 2023 by peril

[peril]

 @m sprank (of course you were right ... ) @DrD123 thanks for the pointers

(and tyvm both) 

got this all fixed up; it was a bit of a saga. (all of the diag stories are.) So one key piece that I left out was that I did the innner / outer tie rods on driver side. and the steering wheel was about 20 degrees to the right (but aligned). 

During the BCM / VDC lost comm codes - I = cleaned all the grounds I could see; and made a replacement strap for the broke one. (there were some strange power off messages)

This was my path (tortuous)

1)2010 legacy - the one throwing codes -  lest week -  I did struts and the the driver side tie rods, and didn't count the turns of the outer to the inner b/c it was jammed tight),  when the shop aligned it - car tracked straight but the steering wheel was 15-20 degrees to the right. <remember this>

2) 2013 outback - changed the inner / outers on my 2013 outback (sons car) and counted the turns for the inners and outers (and they were about 10 for each side) (this was a key hint here) , when I finsihed this -the steering wheel was dead nutz straight  (no more about the outback)

2a)2010 legacy  did the passenger side inner / outer tie rod; 14 turns  (wait a second 4 turns different for the exact same tie rod) 

3) 2010 legacy - went thru each of the codes and cleared out; vdc - throws steering angle sensor message; brake subsystem throws vdc message

4) from "VEHICLE DYNAMICS CONTROL (VDC) (DIAGNOSTICS)" -> found the VDC diag in the subaru manual read it closely -  key piece was this note "Is the deviation from the center of steering wheel less than 5° " (oh hell yeah - it's like 20 degrees)

5) cleared the codes out, and the only codes remaining were the vdc steering, and brake / vdc

6) adjusted tie rods to get steering angle to adjusting to <5; then cleared the brake code, then cleared the vdc code, and done. 

7) then 40 miles test drive and it stayed off.

 

Key insights; check grounds; find the diag procedure for the code from the subaru shop manual, and READ it.

(And always remember that VDC needs the steering to be withing 5 degrees or it will throw an  error in vdc and brake subsystems.)

 

 

 

 

Edited June 25, 2023 by peril

[m sprank]

Oops.  If you had mentioned the tie rods, I would have asked about the steering angle.  But I am very glad you figured it out on your own.  Next time use a strap to "lock" the wheel in position so it does not "spin" on you when free.