Subaru Forester Owners Forum banner

1 - 7 of 7 Posts

·
Registered
Joined
·
3 Posts
Discussion Starter #1
Hello,

Have a 2015 2.5i Premium with CVT that was just purchased used with 15,030 miles. Car is like new as one would expect with such low mileage and it runs and drives fine without any CEL or other notable problems. Therefore was very surprised when I hooked up my Bafx Bluetooth Obd2 through Torque Pro and it reported the below (note: I did adjust the Torque app Preferred OBD2 Protocol to the Subaru friendly ISO 15765-4 CAN 11 bit 500k baud setting) .
-----------------------------------------------------------
Current Fault Log
------------------
P0700: Transmission Control System (MIL Request)
P0890: Unknown code - More information may be available on the web

Pending Fault Log
------------------
ECU reports no pending faults

Historic Fault Log
------------------
ECU reports no historic faults
Other discovered fault codes
(possibly pending, current or manufacturer specific)
----------------------------------------------------
ECU reports no other fault codes logged

--------------------------------------------------------------

Researching P0890 yields "Transmission Control Module (TCM) power relay sense low circuit". Both codes seem to persist as each time I run a new scan it produces the same 2 results. I'm thinking both errors are under the threshold of producing a CEL as again there are no dash lights on.

Have not done any extensive troubleshooting other than checking connections / voltage (which are all good) on a little over 2 year old battery (Interstate MegaTron Type 35 @550 CCA).

I do have it going to the Dealer in a few days for the Brake Lamp Switch Replacement and Coil Spring Check / Recalls, and am reluctant to clear the codes so the Dealer can see for themselves and perhaps provide some additional details (cause and / or fix).

As far as history, when the battery was replaced at a local battery shop the PO reported that a CEL immediately came on which resulted in a trip to the Dealer who replaced a "blown fuse due to overload in the system". The dealer does not have a record of which fuse was actually replaced. I did check cabin fuses 12 and 33 and engine compartment fuses 1, 12, and 13 and all look good.

Unfortunately the car is out of warranty EXCEPT for the extended TRANS warranty until 2025. Perhaps since this is a TRANS related (TCM) error this may be covered by the TRANS warranty ... but not very confident that will be the case.

So .. I'm at a loss on where exactly to go from here, as searching this site I am not seeing any similar type problems.

Any thoughts or advice from the experts here on my dilemma would be greatly appreciated.

Thanks !
 

·
Registered
Joined
·
3 Posts
Discussion Starter #3
Thanks Dogs for the reply, but unfortunately I am having trouble reading the attachment (strange font?). Maybe its just me, but would you happen to have a cleaner copy of this? Thanks !
 

·
Registered
2012 SH Manual Diesel
Joined
·
509 Posts
You will have to take up any omissions and mistranslations with Google. Or insert the Cyrillic text into a more reliable translator.

The Blue coloured text is a translation of the previously attached screenshot. The remainder is a translation of the diagnostic procedure, for that P0890 code.

The Russian version of the workshop manual, was all I was able to find. Not easy navigating the foreign language menus; to find a fault code that you don’t know what it relates too.


CONTINUOUS TRANSMISSION (DIAGNOSTICS)> Diagnostic procedure using Fault Diagnostic Codes (DTCs)
CDN P0890 DIAGNOSTICS SELF-CUT-OFF RELAY AT (LOW SIGNAL LEVEL)
CONDITIONS FOR DETECTING CDN:
• Open or short circuit in the TCM power supply circuit.
• Faulty self-cut relay
MALFUNCTIONS:
Gears are not switched.
CAUTION:
After diagnosing, perform the ECM Clear Memory Procedure.
ELECTRICAL DIAGRAM:
• Left hand drive model
Continuously variable transmission control system

• Right hand drive model
Continuously variable transmission control system



1.CHECK HARNESS.
1) Disconnect the TCM connectors and self-cut relay.
2) Measure the resistance between the TCM connector and the self-cut relay connector.
Connector and terminal
Left hand drive model
(B55) No. 20 - (B220) No. 16:
(B55) # 2 - (B220) # 15:
(B55) # 11 - (B220) # 15:
(B55) No. 22 - (B220) No. 15:
Right hand drive model
(B55) # 20 - (B220) # 30:
(B55) # 2 - (B220) # 29:
(B55) # 11 - (B220) # 29:
(B55) # 22 - (B220) # 29:

Is the resistance less than 1 ohm?

Repair the open circuit in the wire harness.


2.CHECK HARNESS.
Measure the resistance between the TCM connector and body ground.
Connector and terminal
(B55) No. 20 - Body weight:
(B55) No. 2 - Body weight:
(B55) No. 11 - Body weight:
(B55) No. 22 - Body weight:

Is the resistance value 1 MΩ or more?


3.CHECK RELAY POWER SUPPLY CIRCUIT.
Measure the voltage between the self-cut relay connector and body ground.
Connector and terminal
Left hand drive model
(B220) No. 14 (+) - Body weight (-):
(B220) No. 17 (+) - Body weight (-):
Right hand drive model
(B220) No. 28 (+) - Body weight (-):
(B220) No. 31 (+) - Body weight (-):

Is the voltage magnitude 10 V or more?

Repair the open circuit or short circuit in the wiring harness.


4. CHECK SELF-CUT RELAY.
Measure the resistance between the terminals of the self-cut relay.
Connector and terminal
Left hand drive model
(B220) # 16 - (B220) # 17:
Right hand drive model
(B220) # 30 - (B220) # 31:


5.CHECK SELF-LOCK RELAY.
Measure the resistance between the terminals of the self-cut relay.
Connector and terminal
Left hand drive model
(B220) # 14 - (B220) # 15:
Right hand drive model
(B220) # 28 - (B220) # 29:

Is the resistance value 1 MΩ or more?

Replace the self-cut relay.


6. TCM INPUT SIGNAL CHECK.
1) Connect the TCM connectors and self-cut relay.
2) Read the “Control module voltage” data with Subaru Select Monitor.
Is “Control module voltage” 10 V or more?

At the moment, the condition is normal. Check for poor connections at connectors and wiring harnesses, and replace defective parts.


7. CHECKING THE RELIABILITY OF CONTACT.

Is a bad contact detected in the self-locking relay circuit
 

·
Registered
Joined
·
3 Posts
Discussion Starter #5
Thanks Dogs for the translation of the Service Manual extract. I really do appreciate it.

Interesting I was actually able to find corresponding DTC P0890 Service Manual extracts online (for free) for the CrossTrek and Legacy ... but not the Forester.

Also interesting that I am not seeing a CEL or detecting any type of "gear is not changed" condition (although hard to tell as this is my first CVT) and gas mileage seems perfect.

Its going to the dealer tomorrow for the standard recall work and will see what they have to say about these codes and will report back the results.

Thanks again !!!
 

·
Registered
2016 Forester
Joined
·
44 Posts
I had the same tcm code in my 16 xt no cel. I brought the car to my mechanic and was advised that its logged there but its not causing any problems. The code eventually went away on its own
 

·
Registered
2012 SH Manual Diesel
Joined
·
509 Posts
The TCM will log it’s transmission related codes. If it log certain codes repeatedly, or detects a serious issue; it sends the P0700 to the ECM, which is the Mil request code. The P0700 should then activate the dash warning light.

If you use a stand ODB11 reader (i.e. Bluetooth dongle), to clear codes; it generally only clears upper level codes stored in the ECM. Codes that are stored in the other Control Modules, are usually still there.

To clear the codes on the seperate modules, in general a workshop type scan tool is required, that can individually interrogate each Control Module.
 
1 - 7 of 7 Posts
Top