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2005 Outback 2.5xt Limited
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Discussion Starter · #1 ·
if I was just going to replace my TCM because of error code P0725, where is it?

how big of a deal is it to try and pull off and check the connections and put back?

where do I get a new one?

I've seen the errors again a month ago, and now in the heat, I'm getting pretty hot on longer uphills, and just waiting for the main symptom of the engine dying on a slowing down, where it should be down shifting.
 

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OBW H6 VDC, Tribeca, XT6
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under the dash next to the steering column.
in other words stand on your head in the drivers seat footwell area and look up. very easy to swap depending on your size and flexibility.
 

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2005 Outback 2.5xt Limited
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Discussion Starter · #3 ·
very easy to swap depending on your size and flexibility.
Ha! thanks.

any idea on good place to buy one?

and has anyone ever found connection issues that cleaning or reconnecting would fix? ( you know, I'm hoping for the miracle fix here)

Tys
 

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Discussion Starter · #5 ·
how's this? is this the TCM?




can't help but notice it doesn't say TCM on it.....
 

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The indication MT/AT (manual transmission/automatic transmission) suggests it's not the TCM which is for the automatic only. The part number (88281AG10A) corresponds to the Body Integrated Unit.

Looking at some diagrams in the FSM, the BUI is to the right of the steering column; the TCM is to the left of the column, possibly further forward, closer to the firewall.
 

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Outback 2011 3.6R Premium (sold Jan 22)
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How do you test a transmission control unit on the 2003 Subaru Outback (auto transmission)?
Not sure how you can test it except to swap it into another vehicle with the same TCU and test it in that vehicle.

Are you having a particular problem that a forum member may be able to assist with?

Seagrass
 

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Not sure how you can test it except to swap it into another vehicle with the same TCU and test it in that vehicle.

Are you having a particular problem that a forum member may be able to assist with?

Seagrass
Thanks for responding to my question. I have a 2003 Subaru Outback station wagon with about 29,000 miles on it. Fairly young. Just the other day it started giving me erratic deceleration and acceleration problems even though my foot on the accelerator never changed. Erratic shifting too.
 

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Outback 2011 3.6R Premium (sold Jan 22)
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I am not sure whether you may have mistyped the year model or maybe the mileage.

Have you checked the transmission fluid level. A low transmission oil level will cause the symptoms you are describing.

If it is a 2003 Outback with only 29,000 miles do you know if the transmission fluid has ever been changed? Like most automotive fluids, transmission fluid can degrade with age and if it has never been changed it is now around 19 years old!

Before trying to find a replacement TCU or spending any amount of time diagnosing what the problem might be it may be wise to change the transmission fluid first as this is a quick, easy and cost effective thing to do and often shows very good results. Of course this may not be the cause of your problem.

If you are going to change the transmission fluid make sure you use the correct fluid for your vehicle and just do a drain and fill (about 4 quarts required). I would not worry about removing the transmission pan or changing the transmission filter at this stage as you are just trying to determine if new fluid resolves the problems or whether there are more serious problems with the transmission.

If you do want to look further into what is happening in your transmission you may be able to access the TCU using a windows laptop computer a Vag-COM OBD2 to USB cable and the FreeSSM software. This setup emulates The SSM (Subaru Select Monitor) equipment used by Subaru dealers for diagnosing problems.

Hope this helps,

Seagrass
 

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Just the other day it started giving me erratic deceleration and acceleration problems even though my foot on the accelerator never changed. Erratic shifting too.
Seems to be saying the car is accelerating or decelerating on its own, i.e., without an change in the position of the accelerator pedal. That might be the engine, not the transmission. Perhaps more details on the driving situation at the time would help.
 

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I am not sure whether you may have mistyped the year model or maybe the mileage.

Have you checked the transmission fluid level. A low transmission oil level will cause the symptoms you are describing.

If it is a 2003 Outback with only 29,000 miles do you know if the transmission fluid has ever been changed? Like most automotive fluids, transmission fluid can degrade with age and if it has never been changed it is now around 19 years old!

Before trying to find a replacement TCU or spending any amount of time diagnosing what the problem might be it may be wise to change the transmission fluid first as this is a quick, easy and cost effective thing to do and often shows very good results. Of course this may not be the cause of your problem.

If you are going to change the transmission fluid make sure you use the correct fluid for your vehicle and just do a drain and fill (about 4 quarts required). I would not worry about removing the transmission pan or changing the transmission filter at this stage as you are just trying to determine if new fluid resolves the problems or whether there are more serious problems with the transmission.

If you do want to look further into what is happening in your transmission you may be able to access the TCU using a windows laptop computer a Vag-COM OBD2 to USB cable and the FreeSSM software. This setup emulates The SSM (Subaru Select Monitor) equipment used by Subaru dealers for diagnosing problems.

Hope this helps,

Seagrass
Thank you Seagrass. I will take your advice and change the transmission oil first. My Subaru is a 2003 model and the transmission oil has never been changed out. Yes, I have just a little less than 29,000 miles on the car.
 

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Thank you Seagrass. I will take your advice and change the transmission oil first. My Subaru is a 2003 model and the transmission oil has never been changed out. Yes, I have just a little less than 29,000 miles on the car.
Hi Seagrass,
Well, I changed out the transmission oil, about 4-quarts, and the problem persists. I think my next step is to change the external oil filter on the transmission. Next easiest thing. When I accelerate, my tachometer gets up to about 2500 rpm and then drops back to 1500 rpm without me changing my foot position on the accelerator pedal. And then repeats that acceleration and deceleration.
 

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Outback 2011 3.6R Premium (sold Jan 22)
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Sounds like the transmission is “flaring” during gear changes.

Did you use the correct fluid for your model transmission? Incorrect fluid can cause flaring.

Did you check the transmission fluid level with the vehicle on a flat surface and engine running with transmission in Park? A low transmission fluid level will cause flaring.

If the above is all correct it is time for a professional diagnostic at a transmission workshop or experienced Subaru workshop (NOT a dealer).

There is no need to change the transmission oil filter as this will not be the cause of flaring.

Seagrass
 

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Sounds like the transmission is “flaring” during gear changes.

Did you use the correct fluid for your model transmission? Incorrect fluid can cause flaring.

Did you check the transmission fluid level with the vehicle on a flat surface and engine running with transmission in Park? A low transmission fluid level will cause flaring.

If the above is all correct it is time for a professional diagnostic at a transmission workshop or experienced Subaru workshop (NOT a dealer).

There is no need to change the transmission oil filter as this will not be the cause of flaring.

Seagrass
Fluid level is Ok and I used Valvoline Dex/Merc ATF transmission oil which is recommended for Dexron III which my car uses. I took my car to AutoZone to have them check the "check engine" light code and it was the same that my reader gave me...P0731. AutoZone suggested the part that needs to be replaced is a Vehicle/Transmission Speed Sensor, Duralast Part# SU14028, $401.99. What are your thoughts on this? (The automatic transmission speed (ATS) sensor measures the rotational speed of the transmission shafts. Input and output transmission speeds are monitored and relayed to the ECM/TCM by either an analog or digital signal for proper shift points, speedometer operation and transmission diagnostics. Causes for replacement include check engine lamp illumination, poor or erratic shifting, no or erratic speedometer operation and the transmission going into limp/fail-safe mode. NTK automatic transmission speed sensors are made from high strength thermoplastic that is resistant to temperature, moisture and chemicals. Pre-installed O-rings precisely match OE material and diameter for ease of installation and sealing. The sensor output signal matches OE specifications.) Thanks.
 

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Fluid level is Ok and I used Valvoline Dex/Merc ATF transmission oil which is recommended for Dexron III which my car uses. I took my car to AutoZone to have them check the "check engine" light code and it was the same that my reader gave me...P0731. AutoZone suggested the part that needs to be replaced is a Vehicle/Transmission Speed Sensor, Duralast Part# SU14028, $401.99. What are your thoughts on this? (The automatic transmission speed (ATS) sensor measures the rotational speed of the transmission shafts. Input and output transmission speeds are monitored and relayed to the ECM/TCM by either an analog or digital signal for proper shift points, speedometer operation and transmission diagnostics. Causes for replacement include check engine lamp illumination, poor or erratic shifting, no or erratic speedometer operation and the transmission going into limp/fail-safe mode. NTK automatic transmission speed sensors are made from high strength thermoplastic that is resistant to temperature, moisture and chemicals. Pre-installed O-rings precisely match OE material and diameter for ease of installation and sealing. The sensor output signal matches OE specifications.) Thanks.
The flaring happens also when I put the transmission in 2nd gear so I think it may have something to do with the Engine Control System. My battery went flat dead for about 3-days when I left one of the doors ajar. I found this procedure: Engine control system • Let the engine run at idle until it fully warms up (the radiator fan turns 2 times or more) under no electrical load condition. • After the battery ground terminal is connected, wait for 10 seconds or more to turn the ignition switch to ON.
 

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Seagrass,
Well, I made some progress today. I did this sequence: "Engine control system • Let the engine run at idle until it fully warms up (the radiator fan turns 2 times or more) under no electrical load condition. • After the battery ground terminal is connected, wait for 10 seconds or more to turn the ignition switch to ON." Before I did this, I was in "Limp Mode" where I couldn't get out of 2nd gear and not over 30-mph or higher than 2,750 rpm. After I completed, I can now get up to 60-mph and maybe 3,400 rpm. Almost normal driving except for erratic acceleration and my check engine light still comes on. She's going into the shop tomorrow for diagnostics.
 
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