2012 Limited Issues

[Vader33]

Hey guys/gals,

I’ve got a 2012 Limited 3.5L with roughly 120k. Recently it started idling really rough and lit up the CEL, along with “Service Advancetrak,” the TCS lights, and the wrench. It went into low-power mode twice as well. Usually when this happens, all I need to do is pull over and shut it down, wait about 5-10 minutes and restart and she’s fine. All the lights go out and it drives normally.

The last time this happened, about a week ago, I went to the local O’Reilly and had them pull the codes. I had the following:

U0401
U0402 (both are comm errors between the TCM and PCM)
P0102 (Issue with the MAF sensor)

I firmly believe the 0401/0402 codes are just a loose wire, as it’s very intermittent and doesn’t stick around for long.

Secondly, whenever I fill the tank (unleaded only, no E85), the car doesn’t want to crank over. It has the push button start and will attempt to crank over until it times out, usually about 10 seconds. It takes 3 tries until the engine finally cranks. Once the engine starts, I can stop/start all day with no problems.

I’ve got 12.6v in the battery with it off and 14v with it running. Alternator checks good too. I doubt it’s a starter issue because it’s trying to crank.

SO...

Could all of this be solved by replacing the fuel pump? I’m wondering if the rough idle could be caused by fuel starvation and the hard/no cranking at fill up be caused by a bad pump?

I’ve been to 3 dealerships and 2 shops, and nobody seems to have a clue, but want to charge anywhere from $150-$250 for diagnostics and keep it for 2-3 days. Before I spend what could end up being thousands trying to fix the problem I’m curious what you guys think. Thanks for the help!

-Marc

 

[peterk9]

Welcome to the Forum.
I used the Forum's 'Search' feature (upper right) and found this on the hard to start issue. Hard to start after gas fill up

Peter

 

[Vader33]

Yep. I saw that too, and I'm looking at the vapor management valve (or whatever it's called since that apparently isn't a real part) tonight when I get home.

As for the U0401 & U0402 codes, any ideas?

 

[peterk9]

Yep. I saw that too, and I'm looking at the vapor management valve (or whatever it's called since that apparently isn't a real part) tonight when I get home.

As for the U0401 & U0402 codes, any ideas?

Not over and above what an Internet search brings up. Tried searching in the "Discussion" form for them with no results other than your thread.

 

[Vader33]

The codes themselves just say "communication error between TCM and PCM" which leads me to believe it's a loose wire or broken pin. Even the dealerships I called never had that problem.