ABS System Issues

[TainoPapiChulo]

I own a 2008 Subaru Legacy 3.0

Long story short, while I was driving on the freeway, my brakes went stiff and I couldn’t brake. Unfortunately for me, there was stopped traffic while this occurred. Fortunately, I didn’t panic and used my emergency brake and downshifted to slow myself down. I was only five minutes from home when another issue occurred, my car engine started shaking so bad that I thought it was a blown tire. My car had a check engine light, traction control light, cruise control light, and stuck in sport mode all at the same time. I have an autozone one minute from my house so I read the codes and I got P0301, C0045, C0047, and C0052. As I was waiting to turn onto oncoming traffic, my brake pedal went to the floor. I limped it home, and my master cylinder was empty. I filled it up again to see where I was leaking brake fluid. I found the leak and realized it was where this vehicle had a recall on it. The brake lines were completely rusted, so I argued with Subaru of America and got them to fix the brake lines for a $500 deductible. I thought this would fix my issue with my codes to no Avail. I replaced all the spark plugs and coils with OEM parts  and my misfire codes disappeared for about 5 minutes. I cleaned all my grounds. Now I have codes P0301, P0306, P0700, C0047, C0051, and C0071. I honestly don’t know what to do because my car was working perfectly up until my brake line busted.

[silverton]

P codes 301 and 306 are cylinder 1 and 6 misfires and likely unrelated to the C codes.

P0700 means there is a fault in the transmission and it has requested the check engine light to illuminate.

C0047 CAN COMMUNICATION

C0051 VALVE RELAY

C0071 is a strange one... four different things branch from its listing, but all of them are related to the steering angle sensor

All three of those C codes share Fuse No.33 and SBF 6 so I'd start there. SBF6 is in the fuse box under the hood, Fuse No.33 is in the fuse box inside the cabin.

[TainoPapiChulo]

Thank you, my transmission was shifting and working fine up until this happened. I actually didn’t even get the code until I replaced spark plugs and coils. I haven’t driven the car at all since this situation happened. I don’t have an ABS light on the dash either. All my fuses are in good shape as well. I will check SBF, I didn’t know what the pink fuses went too, or how to check them.

[TainoPapiChulo]

Is there a possibility that the ABS module is preventing my car from getting proper electrical power, in other words a “safe mode”. I just don’t understand because it ran fine until this occurred. The brake line is fixed, no leakage, and Subaru bled the system after install. 

[m sprank]

It is more possible that by using the e-brake and downshifting to stop the car you damaged the transmission. 

[TainoPapiChulo]

I didn’t get the transmission code until after I replaced the spark plugs and coils. It has been throwing random codes after I do something else on car.

[m sprank]

In your original post you stated that you stopped at Autozone after the braking event and pulled codes P0301, C0045, C0047, and C0052.  All the the "C" codes point to the ABS/TCM/ECM. 

C0052 = Motor and Motor Relay Off Failure =

• Defective VDCCM power supply circuit
• Loose ground
• Faulty wiring harness
• Poor contact between alternator, battery and VDCCM

C0045 = Incorrect VDC Control Module Specifications =

• Defective VDCCM
• Defective TCM
• Defective ECM

C0047 = Can Communication =

• Poor connector terminal on the VDCCM
• Defective VDCCM

 

 

Edited May 2, 2023 by m sprank

[TainoPapiChulo]

Oh I thought you were referring to P0700. I thought those other codes all had something to do with the ABS system, which made sense because I lost my brakes.

[m sprank]

After more driving you found

P0700 = Transaxle Control System (MIL Request)

C0071 = Steering Angle Sensor Offset i (Too Big)=

• Defective steering angle sensor.
• Defective VDCCM

C0051 = Valve Relay =

• Defective VDCCM power supply circuit
• Bad wiring harness
• Defective VDCCM

[TainoPapiChulo]

I haven’t driven the car, after replacing spark plugs and coils, I let the car idle and those codes popped up

[m sprank]

VDCCM resides in the ABS control module.  This is where I would start.  Then once the car is drive-able again I would be checking the trans and diffs. 

[TainoPapiChulo]

What do you suggest I do? I checked transmission fluid and it’s bright red, differential fluid is full and nice yellow color.

[m sprank]

Repair Procedure:
1. Turn off the ignition switch.
2. Disconnect the negative terminal from the battery.
3. Disconnect the air intake duct from the air box.
4. Remove the air cleaner case from the inner fender.

Removal of ECU:
Note: When removing the ECU, the brake pipes remain connected.

1. Disconnect all electrical connections from the ECU (top and bottom).
2. Remove the two installation bolts (M8) from the bracket of the hydraulic unit and the ECU assembly. See Fig. 1.
3. Lift the hydraulic unit and the ECU assembly from the bracket by about 5 cm (0.2 inches) and support it with a small piece of wood. Caution: Be careful not to deform the brake pipe during this procedure.
4. Unlock the connector for the motor power source and disconnect the connector as shown in Fig. 2.
5. Remove the six torx head screws (T20) which join the hydraulic unit and the ECU. Note: Do not reuse the torx head screws once they are removed.
6. Remove the ECU from the hydraulic unit by gently pulling it. See Fig. 3.
7. Note:

• Do not insert anything into the gap between the ECU and the hydraulic unit.
• Do not pry the ECU, but pull it straight from the hydraulic unit.
• Do not reuse the seal from the ECU.

Installation of New ECU:

1. Confirm that the sealing surface of the hydraulic unit is clean. Note:
   a. Do not machine the sealing surface.
   b. If the sealing surface is damaged, replace the ECU as well as the hydraulic unit and the ECU assembly with a new one.
   c. Clean dust or foreign material from the sealing surface with a clean cloth and alcohol.
   d. Do not blow compressed air onto the ECU surface or the hydraulic unit
2. In order to prevent damage on the valves protruded from the hydraulic unit, do not tilt the ECU against the hydraulic unit when assembling.
3. Install the new ECU.
4. Temporarily tighten the six screws by hand. Note: Do not reuse the screws that were previously removed from the ECU.
5. Tighten the six screws in the exact order shown in Fig. 2; use the specified tightening torque of 2.65 +/- 0.30 Nm(1.95 +/- 0.22 ft.-lbs.) (26.4 in.-lbs.).
6. Make sure the screws are securely tightened by visually confirming that there is no clearance between the ECU and the hydraulic unit.
7. Connect the motor power source connector to the ECU. Note: Confirm that you hear a clicking sound when locking the connector lock.
8. Install the hydraulic unit and the ECU assembly onto the bracket and tighten the two nuts with a tightening torque of 18 +/- 5Nm (13.28 +/- 3.69 ft.-lbs.) (44.28 in.-lbs.). Note: Securely attach the damper under the hydraulic unit with the hydraulic unit and the bracket.
9. Reconnect the ECU harness connector with the ECU.

Restoration of Surrounding Parts:

1. Install the air cleaner case.
2. Install the air intake duct.
3. Connect the negative terminal to the battery.

Testing After Replacement:

1. Confirm that the ABS warning light comes on normally and then turns off when the ignition switch is turned on.
2. Connect the select monitor and confirm in the first display that the model year, driving system and transmission system are correct.
3. Confirm that the ABS warning lamp does not light when starting the engine and driving up to more than 12.5 mph (20 km/h). Note: If something abnormal was found in the above three testing procedures, follow the repair instructions described in the diagnostic procedures of the vehicle’s service manual.

Courtesy of ALLDATA.

[TainoPapiChulo]

I cleared codes, let my engine idle. These are the codes that appeared again.

2008 Subaru Legacy.pdf

[TainoPapiChulo]

I appreciate all the responses and want to be as transparent as possible. I love this car and have put blood, sweat and tears into it. I just want her fixed. I just think she is having electrical problems, I sent her to Subaru a couple years back and spent 2,300 for them to fix electrical problems she was having. The owner before me put in a remote start that eventually nearly caught fire.

I’ve also have been having trouble with the navigation system, it will turn on and then give me a flashing “communication error” before shutting back off. Then the lights on the buttons will flash three times and turn off repeatedly.

I don’t have an ABS light on either, the head gasket is not leaking; I’ve checked oil, radiator reservoir, signs of leakage above and below the engine and no smoke coming from exhaust.

Edited May 2, 2023 by TainoPapiChulo

[m sprank]

Why are you not starting at the source???  Idle and pulling idle codes is wasting time at this point.  Start from the beginning.  You climb a ladder one rung at a time.  VDCC.  You may make things worse with the games you are playing.  You have a major electrical issue if not the ABS module.

 

Make:

Subaru

Code:

C0041

Definition:

Parameter Selection Error

Description:

VDC control module parameter selection failure. ABS, EBD and VDC are inoperative. NOTE: When the VDCCM or VDCCM& H/U is replaced, this DTC may be stored.

Cause:

• Check the identification symbols on VDCCM& H/U
• Faulty VDCCM
• Faulty VDCCM& H/U

 

 

Make:

Subaru

Code:

C0071

Definition:

Steering Angle Sensor Offset i (Too Big)

Description:

DTC is occurs when deviation from the center of steering wheel less than 5 degrees and DTC is displayed. Signal does not come from steering angle sensor.

Cause:

• Defective steering angle sensor.
• Defective VDCCM

 

 

Make:

Subaru

Code:

P1531

Definition:

Battery Current Sensor Circuit High

Description:

Detect the open or short circuit of battery current sensor. Judge as NG if out of specification. Enable Conditions: Battery voltage ≥ 10.9 V Elapsed time after starting the engine > 1000 ms Engine speed > 500 rpm Ignition switch ON

Cause:

• Short/Open between ECM and battery current sensor connector
• Faulty battery current sensor

 

 

Make:

Subaru

Code:

B1101

Definition:

Batt P/Supply Malfunction

Description:

Battery power supply backup circuit is open or shorted. Battery voltage is too high or too low. When B1102 occurs at the same time, all the functions of the body integrated unit may not operate.

Cause:

• Loose wiring harness connection
• Defective fuse
• Bad wiring harness
• Poor contact in Body Integrated Unit connector

 

 

Make:

Subaru

Code:

B1102

Definition:

Batt P/Supply Malfunction Backup

Description:

Back-up power supply circuit input voltage is too high or too low. When B1101 occurs at the same time, all functions of the body itegrated unit may not operate.

Cause:

• Loose wiring harness connection
• Defective fuse
• Bad wiring harness
• Poor contact in Body Integrated Unit connector

 

 

Make:

Subaru

Code:

B1103

Definition:

Ignition Power Failure

Description:

Ignition power supply circuit voltage is too high or too low. Ignition switch turns to ON with the weak battery condition.

Cause:

• Bad wiring harness connection
• Defective fuse
• Open or short circuit between fuse and body integrated unit

 

 

Make:

Subaru

Code:

B1104

Definition:

ACC Power Failure

Description:

ACC power supply circuit voltage is too high or too low. Ignition switch turns to ACC with the weak battery condition.

Cause:

• Loose wiring harness connection
• Defective fuse
• Bad wiring harness
• Open or short circuit between body integrated unit and fuse
• Poor contact in Body Integrated Unit connector

 

 

Make:

Subaru

Code:

U1201

Definition:

CAN-HS Counter Abnormal

Description:

High speed CAN communication becomes unstable.

Cause:

• Bad wiring harness
• Open or short circuit
• Poor connector terminal on the ECM
• Defective yaw rate sensor
• Defective ECM

 

 

Make:

Subaru

Code:

U1202

Definition:

CAN-HS Bus Off

Description:

Open or power supply-output short, GND-output short occurs in CAN line. End resistance malfunction Internal error in each control module

Cause:

• Loose wiring harness connection
• Bad wiring harness
• Poor connector terminal on the ECM
• Defective VDC/ABS Control Module
• Defective body integrated unit
• Poor connector terminal

[m sprank]

Read up:

https://static.nhtsa.gov/odi/tsbs/2013/MC-10065771-3639.pdf

MC-10065771-3639.pdf

[TainoPapiChulo]

I’m not trying to play games, my blue driver code reader came in the mail two hours ago. I wanted to pull codes so I could be transparent with the forums. Is there a way to test the ABS module without just replacing the module?

I also just replaced the battery with an Optima battery last year, so I don’t believe it could be the battery. It sits at 12V and 14V when alternator is spinning.

Edited May 2, 2023 by TainoPapiChulo

[m sprank]

Do you have access to a SSMII?  Something tells me the answer is no.  If you trust the codes they are telling you the ABS failed with the VDCC.  Your brake pedal going stiff and losing the brakes sounds like the tell tale physical symptom.  You can replace the pump and ecm or just the ecm. 

 

Having a charged battery and a working alternator does not equal a healthy electrical system.  Nor does it equal healthy communication among the various devices within the electrical system. 

 

It sounds like you are in over your head and require professional assistance. 

 

e7cf186a-53fe-495c-b6fa-e1adf4a9dfab_EEE1 - abs.pdf

[TainoPapiChulo]

I agree, I am in over my head but I can’t afford professional assistance. I just graduated college and I am currently training for Marine Corps officer program. If I had a study job with a study income, I could get this fixed. Life sucks and than we die, I am coming to a full understanding of what this means. I have to do this myself and I will overcome this obstacle. I will check all the wiring terminals and see what that leads me too. Thanks for your help, I truly appreciate it. I needed an extra brain to guide me through this and I got it.

[m sprank]

Good luck.  Grab a meter and check continuity to ground on the battery, engine, abs ecm, etc.  Can't hurt to check.  Physically inspect the wiring harness and connections at the abs ecm.  Possibly something happened when the system lost all fluid and pressure that damaged the ABS pump/ecm/vdc.  If you replace the ABS ECM/VDC it must be with the exact same part number from the same model year and transmission.  Otherwise you will need an SSMII to "reprogram".  There were a few TSB's over the years with new files to be uploaded into the ABS ECM/VDC.  Buying used you dont really know the part history.  Things get more frustrating as the cars age and the parts and tools become obsolete/out of production. 

[TainoPapiChulo]

I’ve looked up and down the internet and can’t find a diagnosis diagram that fits this ABS module terminal.

 

Update: found a manual, easier to use my laptop than my phone I guess.

Edited May 3, 2023 by TainoPapiChulo

[TainoPapiChulo]

It was raining today, so I figured diagnosing electrical work wouldn’t have been been in my best interest…

So, a few months ago I had a bad squeal that I suspected was my wheel bearings so I replaced all four. I didn’t buy new knuckles which in hindsight would’ve save me a lot of time. When I got the old wheelbearings out, I cleaned the hole where the wheel bearing sits. When I did this, I put anti-seize around the perimeter to prevent future issues if I needed to replace the wheel bearings again. Today I cleaned all the ABS sensors while reading their continuity and they were full of gunk, that I am suspecting is anti-seize. I also noticed that one of my axles isn’t sitting properly in the rear differential. I checked the fluid and it still seems to be in good shape. Not sure if this will throw those ABS codes. I read in another forum that someone with the same issue checked their rear axles and had the same problem, once they popped the rear axle all the way into the differential their issues disappeared. I don’t have a prybar or another tool to get enough leverage to pop it all the way in a place, I also didn’t think that using a hammer would’ve been a good idea. So popping that axle in will be my next project.

[subaru-tech]

So for some reason on these generation legacys when you get abs codes, especially on automatics it causes them to run terrible and they kick the fans on too. Now on subarus there's 2 terminating resistors for the can network. One in the ecm and one in the vdc. You can use pins 6 and 14 of the dlc connector to.check the can network. You should get 60 ohms with everything plugged in, if you ger 120 ohms youve lost a terminating resistor. My guess by the symptoms your having is the vdc module took a dump and is messing with the can network. This is where I would start. 

[m sprank]

Love how the "new guy" responds to threads with the same advice I previously gave.  Vdc failed.

The terminating resistors are there to absorb echo and shadow.  Its a master/slave token passing language.  Even if you lose them the system will still communicate.  You may (most likey will) encounter comm errors though. 

Welcome to the forum.