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Discussion Starter · #1 · (Edited)
Howdy team,
First post! And, I’m asking for help… How about that? I've read a couple dozen threads but haven't seen a clear answer.

Updates from 12JAN21 at 1444 in red

Bottom line up front: I have the Christmas tree light effect on my 2010 Subaru Outback CVT following dead battery. Initial code was p0700 but it cleared after a couple days of driving. Currently, no codes. Car drives fine but the lights haven’t cleared.

Relevant Car data: 2010 Subaru Outback. 2.5i Premium. 169k miles. Car has the CVT tranny. Subaru Seattle replaced CVT fluid at 158k miles.

Tools/Experience: I have a uSCAN tool that connects to my iPhone. Plenty of other tools and about 10 years of working on cars/motorcycles.

Starting Event: Dead battery that was jumped with a small anti-gravity jump box. Then replaced.

Relevant lights: AT OIL light (8 flashes every 2 seconds); Brake Light (Flashing); Traction control (solid). ABS light (solid) No Check Engine Light. ABS codes: C0071, C0073, C0074. TCU Codes

Codes: Currently no codes. Previous p0700 code (permanent) –cleared.

Current efforts & results to date: (1) Attempted to clear p0700 code immediately, but it was permanent. Code cleared after a few days <100 miles of driving. (2) Personally replaced battery. Battery replaced with an O’Reilly Brand battery (Super Start Economy). ******. (3) Checked all the lights in the car, replaced one rear (red) driving light in the back. Front right fog light is out and has been out for some time. ******. (4) Replaced gas cap and ran car ~100 miles. ¼ tank of gas. ******. (5) Unplugged positive terminal overnight last night. Started the car up with same symptoms and no codes. ******. (6) checked all fuses. Nothing blown. No corrosion. ******. (7) Checked alternator by checking voltage across battery when car was running. 14.7 volts ******. (8) Done the locking/unlocking rain-dance with the key fob. ******.

  1. Intended COAs:
    1. (1) Replace negative terminal. (The negative terminal is old, I recently cleaned it. There is a small brake in the loop. BUT, IT IS VERY TIGHT.) Completed, ******
    2. (2) Take car to O’Reilly’s and see if they can read codes my uScan tool isn’t seeing. Completed, Confirmed 03 ABS Codes, No TCU codes.
    3. (3) After reading another thread: try turning the key to the ON position, hold your foot on the brake pedal and pull out the emergency brake.Completed, ******

Other thoughts: I understand I need to look for some TCM codes, is this something a scanner can get at a local Autozone-O’Reilly?. (2) The nearest Subaru dealership is about 1.5-2 hours away (A lovely effect of being stationed at a remote location in the Coast Guard).

Threads I’ve read:
Flashing AT oil temp, brake, and solid traction control | Subaru Outback Forums
All the warning lights lit up | Subaru Outback Forums

Thanks team!
 

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new battery and leave it disconnected for 15 minutes
turn car on, wait 15 seconds, start
reconnect and report back after letting car idle for about 15 minutes
 

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Discussion Starter · #3 ·
new battery and leave it disconnected for 15 minutes
turn car on, wait 15 seconds, start
reconnect and report back after letting car idle for about 15 minutes
Thanks for the reply.

You mean a second new battery? Maybe I could tell O'Reilly's I'd want a different battery since it's only been a few days.
 

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The P0700 code is set by the TCU advising the ECU that the transmission has a problem. It is NOT a specific code for a problem it is an advisory code only.

You need to get the DTC (Diagnostic Trouble Codes) read from the TCU as the TCU codes will give more information to help with the troubleshooting.

I suspect it will be a TCU code advising there is a valve body solenoid that has failed as this is one of the common faults of the CVT transmissions with your mileage.

Hopefully your local auto part store will have a scanner that can read the TCU.

Seagrass
 
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Discussion Starter · #5 ·
The P0700 code is set by the TCU advising the ECU that the transmission has a problem. It is NOT a specific code for a problem it is an advisory code only.

You need to get the DTC (Diagnostic Trouble Codes) read from the TCU as the TCU codes will give more information to help with the troubleshooting.

I suspect it will be a TCU code advising there is a valve body solenoid that has failed as this is one of the common faults of the CVT transmissions with your mileage.

Hopefully your local auto part store will have a scanner that can read the TCU.

Seagrass
Thanks Seagrass, I saw your posts on some of the other threads. Appreciate you weighing in.
I'll give a call to my local auto parts stores (NAPA, O'Reilly, and AutoZone) and see what they say. Does anyone know...if any of the major chains would carry a reader that could read these codes?
 

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Discussion Starter · #6 ·
The P0700 code is set by the TCU advising the ECU that the transmission has a problem. It is NOT a specific code for a problem it is an advisory code only.

You need to get the DTC (Diagnostic Trouble Codes) read from the TCU as the TCU codes will give more information to help with the troubleshooting.

I suspect it will be a TCU code advising there is a valve body solenoid that has failed as this is one of the common faults of the CVT transmissions with your mileage.

Hopefully your local auto part store will have a scanner that can read the TCU.

Seagrass
One follow up. Do you think it's relevant that the p0700 code cleared?
 

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No relevance it cleared. If you drive the vehicle enough I suspect it will appear again when the same conditions arise.

Seagrass
 
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Discussion Starter · #8 · (Edited)
Update 1: 12JAN22 at 1444:

Went to Oreilly's, here is my report
Recent Efforts:
  1. Replaced the negative terminal. It's not firmly attached. ******
  2. Asked them to change the battery they gave me. The Asst. Manager on Duty said he would check, but since the battery voltage is good and properly cranks the car, he thinks its not the problem.
  3. Used their OBII DTC advanced reader and got 3 ABS codes: C0071, C0073, C0074. I attempted to clear the codes, but they didn't clear.
  4. I tried turning the key to the ON position, with my foot on the brake pedal and pull out the emergency brake. ******.
  5. @YeuEmMaiMai suggested I unplug the battery for 15 minutes, let it sit for 15 seconds before turning her over, and letting it idle for 15 minutes. I did it with ******.
Intended COAs:
  1. (1) research and attempt to clear the three ABS Codes.
  2. Recheck the fuses (#5) and inside fuse (#33) Previously checked without issues

Other notes:
  • check brake lights > no issue
  • check brake fluid > no issue
Reading assignments:


Thanks Team
 

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Discussion Starter · #9 ·
I found TSB: # 06-41-11 and it seems to fit the bill for the ABS codes...
"If the battery voltage drops below a predetermined value before the recording process has been completed, the learning value is lost and a DTC will be stored and MIL turned on the next time the IG (ignition) is cycled to the ON position. As an example, if the engine is started by jump-starting and the IG is switched to OFF before the battery has regained sufficient voltage, the learning value will be lost."

The attached TSB describers the process. I'm fairly new to working on Subarus, is this something I can do with ROMRAIDER or FREESSM?
 

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I want to clarify a couple things about scan tools. Some scan tools cannot read the transmission and the ABS modules so you have to have the proper diagnostic tool with the proper software in order to get accurate information from these modules. Just because a module at the parts store can read the codes on the transmission or the ABS does not mean that they can clear the codes and reset the modules.

Next is the codes that you posted as retrieved from the transmission. C codes are communication codes which is generally related to a poor connection to the battery or bad grounding.

71 is steering angle sensor. I have never changed the steering angle sensor in a Subaru. Any year model.

73 is the lateral g sensor. Same as with the steering angle sensor, never changed one.

74 is the master cylinder pressure switch. I've never changed one of those either.

So you've either got a bad connection from the battery to the engine block because the ground is bad which would in turn make the ABS module grounding bad and it would get loopy feedback or none; or there may actually be a problem with your abs module.

The way these cars are designed and the operation of the VDC system, the engine, the transmission, and the brake system all work in conjunction. If there is a problem with one you have a problem with all three.

Since you have a new battery I suggest you find somebody with a conductance tester and check your grounds. If after you fix the grounds and the problem goes away, then it's all good. If the problems are still there after fixing the grounds, then I'll post up a diagnostic tree for you to follow in checking where the problem lies with the communication through the ABS module.
 

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Discussion Starter · #11 ·
I want to clarify a couple things about scan tools. Some scan tools cannot read the transmission and the ABS modules so you have to have the proper diagnostic tool with the proper software in order to get accurate information from these modules. Just because a module at the parts store can read the codes on the transmission or the ABS does not mean that they can clear the codes and reset the modules.

Next is the codes that you posted as retrieved from the transmission. C codes are communication codes which is generally related to a poor connection to the battery or bad grounding.

71 is steering angle sensor. I have never changed the steering angle sensor in a Subaru. Any year model.

73 is the lateral g sensor. Same as with the steering angle sensor, never changed one.

74 is the master cylinder pressure switch. I've never changed one of those either.

So you've either got a bad connection from the battery to the engine block because the ground is bad which would in turn make the ABS module grounding bad and it would get loopy feedback or none; or there may actually be a problem with your abs module.

The way these cars are designed and the operation of the VDC system, the engine, the transmission, and the brake system all work in conjunction. If there is a problem with one you have a problem with all three.

Since you have a new battery I suggest you find somebody with a conductance tester and check your grounds. If after you fix the grounds and the problem goes away, then it's all good. If the problems are still there after fixing the grounds, then I'll post up a diagnostic tree for you to follow in checking where the problem lies with the communication through the ABS module.
Appreciate that input. I've been attempting to track down the grounding locations to make sure nothing to disconnected. Given the shape of the stock negative terminal (rusted out) I wouldn't be surprised if something had broken loose. This car has been in a coastal environment the last 8 years (CT shoreline, an Island in Washington, and now Astoria, Oregon).

I'll check it out this afternoon & report back
 

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Discussion Starter · #12 ·
I want to clarify a couple things about scan tools. Some scan tools cannot read the transmission and the ABS modules so you have to have the proper diagnostic tool with the proper software in order to get accurate information from these modules. Just because a module at the parts store can read the codes on the transmission or the ABS does not mean that they can clear the codes and reset the modules.

Next is the codes that you posted as retrieved from the transmission. C codes are communication codes which is generally related to a poor connection to the battery or bad grounding.

71 is steering angle sensor. I have never changed the steering angle sensor in a Subaru. Any year model.

73 is the lateral g sensor. Same as with the steering angle sensor, never changed one.

74 is the master cylinder pressure switch. I've never changed one of those either.

So you've either got a bad connection from the battery to the engine block because the ground is bad which would in turn make the ABS module grounding bad and it would get loopy feedback or none; or there may actually be a problem with your abs module.

The way these cars are designed and the operation of the VDC system, the engine, the transmission, and the brake system all work in conjunction. If there is a problem with one you have a problem with all three.

Since you have a new battery I suggest you find somebody with a conductance tester and check your grounds. If after you fix the grounds and the problem goes away, the all good. If the problems are still there after fixing the grounds, then I'll post up a diagnostic tree for you to follow in checking where the problem lies with the communication through the ABS module.
I gave a look and the groundings directly from the battery look good. I found two: one attached to the frame on the driver side and one attached to the back of the engine next to the starter.

as far as conductance test, I’ll swing by the O’Reilly and see if they can hook me up. None of my local friends know how to open their hood!!
 

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O'Reilly's sells the Midtronics PBT series tester, so they may have one laying around to loan and show you how it works.

Given the condition of the ground clamp, I suggest you get a battery cable set from Subaru and a new positive clamp, it won't come with the cables, and swap out your battery cables.

There should be a radio suppression ground between the trans to the pitch stop bracket on the firewall. Other grounds would be from the cylinder heads to body. There is a ground coming out of the harness near the ABS/VDCCM that bolts to the frame in the same vicinity.
 

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Discussion Starter · #14 ·
O'Reilly's sells the Midtronics PBT series tester, so they may have one laying around to loan and show you how it works.

Given the condition of the ground clamp, I suggest you get a battery cable set from Subaru and a new positive clamp, it won't come with the cables, and swap out your battery cables.

There should be a radio suppression ground between the trans to the pitch stop bracket on the firewall. Other grounds would be from the cylinder heads to body. There is a ground coming out of the harness near the ABS/VDCCM that bolts to the frame in the same vicinity.
Tested the two grounding wires and had Napa do the same. Both tests didn’t reveal any resistance in the lines. Method was

NAPA didn’t have another way to test the battery. I might try and swing by O’Reilly tomorrow.

I replaced the negative terminal a couple days ago. Positive champ seems in fine condition.

I'll attempt to locate and test the other two negative leads you specified.
 

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When using a multimeter to test the grounds you want to see 0. Not 0.01 or higher.
 

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Discussion Starter · #16 ·
When using a multimeter to test the grounds you want to see 0. Not 0.01 or higher.
Yep. I should clarify. I saw 0.0 . No resistance on my device or a neighbors.

The NAPA multimeter wasn’t great. The base resistance was 1.1 (not zero). (I’m not impressed with the NAPA in this town.)

I’m not ruling out a blown grounding wire, certainly possible, but the engendering event was a dead battery that I jumped. So, I’m inclined to think the system is having trouble relearning it’s parameters like discussed in the TSP.

With regard to the other two grounds, I’ll get to it in a day or so. I recently had surgery and the body isn’t healing as it should. Likely credited to my inability to sit still.
 
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