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My mom's car. She was driving up to visit my kids. Her AT Oil Temp light began flashing. Looked it up to find that being an error code, I told her to continue on carefully. After about 20 miles, the light came on solid, indicating transmission overheating. So she pulled off and let it cool off.

I read a P2764 code (Lock up solenoid low). She got a rental car, and will be leaving hers with me, so I'll do some diagnostics this weekend, but the symptoms fit that the converter wasn't locking, which would generate quite a bit more heat on the highway.

I remembered that solenoids are not available separately, and handing out valve bodies a lot when I worked at the dealership. Called over there, sure enough, they have one on the shelf (MSRP $808). So for nearly $1500. Quick google search pops up numerous individual solenoids available aftermarket for about $100.

The valve body is on top of the transmission, theoretically accessible from the engine bay (don't have to drain the fluid!).

 

 

I'll update with my findings. Any suggestions/experience appreciated.

Edited by Numbchux
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7 minutes ago, 1 Lucky Texan said:

fluid level OK?

did Mom's car sit unused during the recent slow-down such that there could be rodent-chewed wiring or????

just hoping it isn't internal......

CVT Fluid level is not easy to check.

Nope. She drives the crap out of it.

 

We replaced a lot of valve bodies at the dealership with good results. And the code only refers to the electrical circuit, so it really has to either be the solenoid or wiring to it.

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Owning a 2014 Impreza, yeah I went thru this also at 132K mikes. Valve body best price was about $800 .... then in FSM says after replacing, check fluid level by ATF temp, then do CVT retrain.

Valve body kit includes a plastic bonnet you put all around AFTER you remove the intake tube, throttle body ( just remove 4 bolts and push to one side ) and the dogbone and bracket to get to top of transmission.

Also FSM has you replace the 2 O-rings on the bottom of the valve body, and retorque to in-lbs the few bolts holding the valve body in place .... in a tight area unless you have a small torque wrench.

Being a mechanic for over 45 yrs, and reading about the successful and a few that were not and wanting this to work for a long time INCLUDING the retraining ( some say it's not required but I follow the FSM ), I went back to dealer I bought the last several Subaru's from and know the service manager ( we worked together in the past ). $1350 for all .... 2 qts fluid, valve body, retrain and all done in a day. GRANTED he gave me a break, but for me it was worth it. Car shifts better than before.

My experience and observations.

Edited by Ferret54
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I followed the FSM diagnostic procedure. Tested the wiring for a short, none. Tested the resistance of that solenoid, should be about 13 ohms, and it reads about 3. I picked up new orings and a cover gasket from the dealership, and I'll remove the valve body tonight (I'll do the other test while it's out to test the short section of wiring that goes into the trans then). New solenoid is scheduled to arrive tomorrow. I'm hoping to drive it to work on Thursday, and her rental car has to go back on Friday.

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Did a little experimenting last night. The Android program ActiveOBD can read lock up duty with my Carista ELM bluetooth dongle. If I shut off the car and clear the codes, and then try to drive it, it will try to lock up the converter 2 or 3 times, and the car lurches a bit as it happens, then the light starts flashing. Once the light is flashing, it doesn't even try to lock it up.

Solenoid is supposed to arrive today, so I started tearing it down last night. The 2 steel dowel pins in the aluminum housing after 185k Minnesota miles put up quite a fit (I don't know why it has pins at all, it's just a cover, the alignment is not that crucial). There is nothing on the edge to pry from. There's a boss for a bolt for a ground wire on the left front corner of the cover. I threaded a longer bolt in there, and was able to use the claw of my hammer to pry up on that on the ground bracket for the starter, and wedge the handle of the hammer against the cowl. I called it quits after that, so hopefully the body comes out without a fight (I suspect I'll have to remove the pitch stopper bracket from the transmission, at least, to make room) and I can get it all put back together tonight.

 

Interestingly, the catalog shows a gasket for that cover by VIN. But it was sealed with just a smear of FIPG (the perfect amount, so I think it was probably factory). New gasket is a stamped steel one like an OEM water pump gasket.

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Pitch stopper bracket removed, and throttle body to make it easier. And the valve body came right out.

This article shows which bolts hold the valve body in. And which solenoid is which.

https://gearsmagazine.com/magazine/subaru-cvt-gen-2-valve-body/

Found this video showing how to release the wires from the solenoid.

https://www.youtube.com/watch?v=L6FaBvGSTec

 

 

The cavern where the valve body was:

51256096345_d80754986b_c.jpg

20210616_212603 by Numbchux, on Flickr

 

The culprit (or, rather, the replacement...)

51255258803_528c5a22b8_c.jpg

20210616_210238 by Numbchux, on Flickr

 

I've driven it about 4 times, since. The Pending and confirmed codes cleared and have not come back. I haven't driven it enough to clear the Permanent code, but I have no reason to suspect that won't come.

 

It is interesting watching the function. Once the transmission is warmed up, it locks the converter at about 15 mph, and lets the transmission do it from there on.

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I ordered on Amazon for the quick shipping. Here's the exact one I purchased:

https://smile.amazon.com/dp/B07XDNHQTM?psc=1&ref=ppx_yo2_dt_b_product_details

 

If you search the valve body part number (31825AA052) on Amazon, there are about 20 listings for the solenoid. I just picked the one I could get the quickest. I've seen some reviews saying they had these aftermarket solenoids not last nearly as long as the original (failing within weeks or even months...), so time will tell. But I wouldn't mind doing this a few times over the rest of the life of the car rather then spend the money on a new OEM valve body.

 

Interestingly, I read that the lock up solenoids and at least the 2 shift solenoids are the same (AWD solenoid sure looks the same, too. But that was not listed where I saw this), so pulling used shift solenoids from core valve bodies to replace the lock up solenoid is a decent option.

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  • 2 months later...

I picked up a used valve body just in case the cheap solenoid failed.

 

Well....it threw a P2764 again yesterday. Barely more than 2 months. I wasn't expecting to get another 185k miles like the stock one....but, that was disappointing.

 

I plan to swap in a used solenoid from the other valve body tonight.

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7 hours ago, GeneralDisorder said:

We have had 100% success replacing the valve body and the short wiring harness. 

GD

No surprise. But it doesn't need a complete valve body at $800. It just needs one solenoid. I know, I'm a cheapass.....

 

The A and B shift, and torque converter solenoids are all identical should all read between 10-13 ohms. The OEM one that failed read 3 ohms. This aftermarket one..... 0.2 Ohms....

From my research. The torque converter solenoid is by far the most common to fail, despite the fact that the 2 main shift solenoids are identical. So I got a used valve body with less than 100k miles on it that had a failed AWD solenoid. I grabbed one of the shift solenoids, and swapped it for the converter solenoid in my mom's car last night. Code cleared, test drove great. The car has about 190k on it, now. If it lasts another 50k, I'll be happy. If not, I have 2 more used OEM solenoids on that valve body that test good....

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