Anybody have any experience with an intermittent p1774?

[AvalancheX]

I have a 2011 X with 150,500 miles that randomly goes into limp mode and will only throw a p1774 (low coast brake solenoid valve function). It always does it within the first couple of miles of driving. If I pull over, cut the vehicle off and start it back up it will drive normally for a random amount of time and it will either eventually stop doing it completely and the check engine light will turn itself off or it will start doing it more frequently until I clear the code. After I clear the code or when the CEL cuts off it will drive normally sometimes for months without issues and shift smoothly and then sometimes it’ll do it again the next day. I’ve replaced the solenoids and drained and filled the fluid several times since I’ve owned it. Should I have replaced the entire valve body and TCM, along with the solenoids or could it be something else? It happens so randomly I know if I take it to somebody to diagnose they very likely won’t be able to duplicate it and likely try to sell me a transmission which I don’t really think it needs. Anybody have any advice on this one?

Also, I just want to add that I'm aware of the TSB regarding this issue and checked continuity on all of the circuits on the TCM when I changed the solenoids and they looked solid and unbroken. The battery is 3 years old exactly and I'm unsure of the age of the alternator. I'm kind of wondering if there could be a random voltage drop or surge due to a failing voltage regulator maybe?

 

[TerryD]

Have you checked the grounds? Intermittent electrical issues like you're having, the grounds are a good place to start.

Do you know if the transmission has ever been overheated or the valve body removed? It could be a warped valve body causing the issue as well.

 

[AvalancheX]

As far as I know, it's never overheated. I've never used it for towing and I don't think the previous owner did either but I suppose anythings possible. I removed the valve body when I did the solenoids, but removed it cold and torqued back to spec when I reinstalled. I haven't checked the grounds. Couldn't get the main harness connector(the one outside the trans. on top) to break loose when the solenoids were replaced and ended up disconnecting the wires inside the pan to get TCM free. Any tips on getting that disconnected? From what I'm reading in the FSM, that has to come off to start checking grounds.