First time I ever posted, so if I don't follow protocol don't yell too much. The problem is my console panel goes bi-polar as I'm driving, idiot lights go on, gauges stop working, turn signals don't work, and after a few seconds later, all is well. I never lose power, but when this problem starts, it does so until I turn off the car. (Several times it took about 10-15 times turning the key to start the car as well.) I replaced the battery, looked at every fuse and relay for corrosion and melting, cleaned the lug at the backside of the underhood fuse panel. My mechanic got error codes of U2107, "lost communication w/ body control module" and U2129 "lost control w/ remote function actuation." I found on line some one saying " failure in data line." I would appreciate any help or suggestions. Thanks in advance

 

Check the underhood fuse box. Lots of info all over about the HHR's fuse box halves getting loose over time.
There are even some Youtube videos about this.

Oh yeah. Welcome to the forum.

 

x2 what FMG says.

Here's a link to a page with a video that Donbrew posted a while ago that shows the process of pulling the fuse box apart - Chevy HHR Fuse Box Removal ? YardZoo

 

Thanks for posting so fast. I saw the videos, check to make sure the two halves of the underhood fuse box was tight and they were; no wiggle room.

 

Did you have the problem BEFORE replacing the battery?

Oh, and did you actually dismantle the under hood fuse box, or just tighten it back down?

 

The ever popular "recall been done"?

The "lug on the backside" does that mean the red wire on the outside of the fuse box closest to the driver? If so, that is the power supply for the Power Steering. The other one is the supply for the fuse box.

Those codes mean that for unknown reasons the CANBUS is not working between those modules; could be a fuse, a wire, a module, a connector. The CANBUS is basically a computer network.

 

This is how to diagnose; in your case the BCM is closest to the OBD2 connctor (DLC). You also need to know if the codes are history or current.

The modules needing testing are the BCM and the RCDLR.
Any mechanic should have access to this full section either on Mitchell or AllData.

 

Yes, I had the problem BEFORE I replaced the battery, and the problem persisted. Thanks for the info on the back lug about the power steering. As for the last post, KABOOM - mind blown! I'm going to share this post with my mechanic. Thanks a ton to every one; I'll let you know if we had success.

 

Welcome to the site, just wanted to add in check your ground wire connections, are they clean and tight?