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2011 Outback P0700, P0890, P2764: Location and Part Number of TCM Power Relay ("Self Shut Relay")

328 Views 8 Replies 2 Participants Last post by  Rymar
My son-in-law had their 2011 Outback show the following error codes.
P0700 - TCM says there is a problem
P2764 - Lock-up duty solenoid is faulty or output signal circuit is shorted
P0890 - Power supply circuit of TCM is open or shorted; Self shut relay malfunction

There were no noticeable drivability issues with the car, and it was not below freezing (so it seems like TSB 11-200-20R does not apply).

I did a bunch of searching, both on subaruoutback.org, and on the the web in general, and can't find many cases of a P0890 error. I'm focusing on this electrical problem, since this affects the main solenoid power supply to the TCM, and this could then cause the P2760 solenoid error. I think "self-shut" really means "self-shutoff", but I'm not sure. P0890 is also shown as "TCM Power Relay Error" for other cars/models.

From the FSM, here is the drawing for P0890:
Font Rectangle Parallel Slope Number


While I couldn't find any instances of a P0890 error actually requiring replacement of this relay, I would like to be able to identify where this relay is located in the car, and what the part number is. I've been unable to find any location info in the FSM, or any part number after searching multiple Subaru OEM parts sites, including parts.subaru.com.

One clue is that the relay plugs into connector B494. Looking in the Wiring section of the FSM shows this drawing. At the lower left, which I think is just next to the interior fusebox, is B494.
Vertebrate Organism Font Art Auto part


In the online parts guide, the closest info I could find was this (could they have made this more difficult to read?):
Rectangle Font Parallel Pattern Screenshot

Which, if you can read it, shows the "SELF SHUT RELAY" on "FIG.184". But there is no link, and no way to find where "FIG.184" is!

I found this drawing which shows a relay (circled in yellow) on the lower left of the interior fusebox, about where B494 probably is in the car. It also says FIG.184. But no part number is given.
Font Parallel Slope Rectangle Pattern



I don't have access to the car, so I can't check for a connector which looks like B494 at this location: it should have 4 contacts, and be "at the end" of a wiring harness, as shown above.

My son-in-law cleared the error codes using an OBD code reader, but they reappeared today. He is also trying disconnecting the battery for 10 minutes, as there were recently 2 different incidents where the battery was drained. Perhaps the TCM logged this error, and is now sending it repeatedly to the ECM?

Thanks for any info.
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Discussion Starter · #2 ·
OK, just spoke to my son-in-law again, and after clearing the codes, he said they re-appeared, this time without the P0890 code; so just the P0700 and P2764 codes. So perhaps not the TCM power relay. Now reading about P2764 solenoid replacement.
 

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I would replace the battery, make sure the grounds are good and then check the valve body function. It may be a bad solenoid, but it could also be power supply in general.
 

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Discussion Starter · #4 ·
I would replace the battery, make sure the grounds are good and then check the valve body function. It may be a bad solenoid, but it could also be power supply in general.
Thanks. That seems worthwhile, given the time/expense of solenoid (or valve body) replacement.

I haven't been able to find anyone who says they had to replace the TCM power relay, so I'm thinking that the initial P0890 code was more an indication of low voltage into the TCM power relay, rather than a relay failure. They don't seem to fail much. Also the solenoid error code is P2764, not P2763, which I think also describes a low voltage condition (in the high state) of the PWM (Pulse Width Modulation) driver to the solenoid. Which would also fit with a low voltage into the TCM.

From the schematic, there are 3 connector pins into the TCM from the power relay, B2, B11, and B22. This is the solenoid power supply input, and the use of multiple pins indicates that the current capacity of 1 pin was not sufficient.

Rectangle Font Slope Parallel Pattern



I asked my son-in-law to check for lockup operation, by putting the car in "M" while cruising, and then applying a bit more gas to see if the engine revs go up more than road speed would indicate. Also to feel for the "bump" when coming to a stop, when the torque converter unlocks, around 16-20 mph. Any other checks?

I will also have him check the battery connections and wiring, and for low resistance from the battery negative terminal to the alternator case. And to try unplugging all the connectors into the TCM, and reinserting them.

Is there any other particular power or grounding area to look at, in your experience?

Thanks again. I sure hope its an electrical problem, not the solenoid.
 

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All the ground connections in the engine bay are for electrical operation and computer feed. If there is one bad ground, the others are probably in the same condition.

A good scan tool that can see TCM data will allow you to see TCC lockup and Transfer Duty for the AWD. Some phone apps like Blue Driver will also let you see transmission data. TCC lockup condition can be verified by TCC Slip speed variations when the TCM commands a lockup.
 

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Discussion Starter · #6 ·
I finally found the location and part number of the TCM power relay ("SELF SHUT RELAY"), although I don't think it's at fault:

Product Font Rectangle Parallel Schematic


It is on the lower left of the interior fuse box. Part number is 82501AE03A.
 

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Discussion Starter · #7 ·
OK new battery didn't help. Resistance from battery ground to alternator case is about 0.2 ohms; same with resistance from battery ground to transmission case. Wiring looks good.

The lock-up duty solenoid resistance measures 11.5 ohms when cold, and 14.2 ohms hot (maybe 170F AT fluid temp?). Measurements are from pin 2 in T4 on top of the CVT, to the transmission case.

The only codes now appearing, which happen after warm-up, are P0700 and P2764. And P2764 should indicate a low resistance connection, not the normal values measured. So is it possible that the solenoid is only shorting out when it starts operating, so you can't see the short in the windings with a static resistance measurement? A Mr. Subaru video of a P2764 error shows a static measurement of 1.5 ohms for the same solenoid.

I think SIL will be replacing just the solenoid, rather than the entire control valve body: it's now $811 at the local Subaru dealer.. I hope the reliability of the replacement solenoid will be good.
 

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Discussion Starter · #9 · (Edited)
Success! My son-in-law completed the solenoid replacement last night, filling the transmission at 1:45am in their driveway in Portland, in 28 degree weather. It took just under 9 quarts of fluid, but now drives perfectly. The solenoid he bought was this one:


Is it any better/different than the Kuauto one on Amazon? That's unknown.

I warned him that it might fail, given the reputation that these solenoids seem to have earned. But, at that point, if he needs to replace the entire valve body with the Subaru OEM part, he will only be out the $100 for the solenoid; the CVT fluid can certainly be reused as it will be nearly new. Same for the 3 O-rings.

Plus, it will take him less time, since things are always easier the second time you have to do something.

The old solenoid never tested bad, based on the P2764 error: it should have read as low resistance, but the static resistance measurement when cold was 10 ohms. At the low end of the range, but I think it was failing intermittently with a much lower resistance, after it warmed up and was operating. I asked him to save if for me, so I can cut it open and do a failure analysis.

Thanks to all on subaruoutback.org for the help. It would not have been possible otherwise. See, the internet is good for something!
 
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