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Hey forum, Hopefully I can explain this clearly.
I have a 2007 TL with 227k mi on it, I had Aamco rebuild my trans(at 190k) and after 40k more miles I'm getting a P 0842 trouble code with the check engine light and the trans in safe mode.
It all started with a P 0767 code and I researched a solution that required removing the linear solenoid assembly and cleaning out the pipes inside. Well I did that but had to replace the linear solenoid because I damaged the original and could no longer trust it. I also replaced the pressure switch(28600-RKE-004) right next to the solenoid. Problem fixed? yes, for about two days. That's when the P 0842 started and I've been confused ever since. The rear pressure switch is usually the problem in this case so I replace that one but the code doesn't go away. I reset it and it may go away along with the check engine light but it comes back intermittently. I even unplugged the rear switch just to see what happens and I get a P 0843 trouble code which goes away when I plug it back in.
Any ideas?
When was the last time you did a 3x3 drain and fill using dw1? If that doesn’t solve it, the internals are toast if the new pressure switches didn’t fix the issue.
Sorry guys I was completely sidetracked by life's other issues to get back to you. Yes I've completed two full fluid changes throughout this issue and at the moment, believe I'm on the right track for a solution. I realized that I was only checking the dual linear solenoid
(28250-RDK-014)
on the side of the transmission and not the single linear solenoid
(28260-RDK-023)
on the top. Upon inspection I noticed there was a 90% obstruction in one of the flow pipes
(22770-P7Z-000)
and was able to clear it. It worked! The transmission shifts normally again without any codes. I would recommend clearing these pipes in both linear solenoids to anyone in the future who has this type of problem. I attached pics of the mentioned parts involved.
Glad you seemed to have sorted it out! If you have an 07, you have an internal filter in the bell housing that unfortunately can't easily be replaced, but short of that, I would only suggest doing fluid changes beyond a 3x3 service to make absolutely sure that that debris in the linear solenoid tubes have been completely flushed from the system.
Also, I realize the pipe itself was clogged, but were you able to run ATF through the solenoid itself to make sure there's no debris built up that could cause it from fully engaging in the future?
No I didn't but that's a good idea. I had to order a new gasket and o-rings so I'll check that when i take it off again. Thank god its so easy to get to. I think I'd feel better if I checked the dual Solenoid as well but that's a bigger job and its less than a foot away.
I just read a post on FB about a trans failure. Apparently the filter disintegrated and clogged that same tube on the linear solenoid. His was an 04 though with the external filter. Now I am curious as to whether this is something we can expect to start seeing...
That's funny, I just read something about a internal filter on 07's. Why internal?
Now I have a new problem, I managed to strip the transmission drain bolt threads and it won't tighten enough to stop a slow leak. I found a MDX forum where someone claims to have found a drain bolt from another make(Volvo) and since its longer it can fit his car because it matches the remaining threads on the trans case. I look at my case and it seems like the threads go farther than the standard drain bolt so maybe this works for me.
