Good afternoon!

I've been through the search for the primary problem code and didn't see a situation that matches mine.

When I drove my HHR (2010) on Thursday, it had a hell of a time switching gears, and the speedometer, tachometer, and gas gauge were bouncing all over the place. Also, the check engine light was on, as was - for some reason I can't fathom - the anti-theft light, even though I'd used my key fob to unlock the car.

I drove it again today, and the only issue that popped up was the check engine light. All the other issues were gone. I popped into an auto supply store and asked them to give me a readout of the codes, and this is what they came up with:

U0073 - Control Module Communication Bus A Off
U0100 - Lost Communication with Engine Control Module
TWO P0700 - Transaxle Control Module (TCM) Malfunction

Funny thing is, as soon as he disconnected the reader, the check engine light went off. I drove for a bit more running the rest of my errands. The check engine light stayed off, and the car drove just fine.

All that being said, I have a few questions.

1. What difference does it make that there were two P0700 codes?
2. Do I need to check or poke at anything, knowing that the problem seems to have gone away completely?
3. If I do need to check something, I will love you forever if you can link to a video or picture that shows me exactly what I'm looking for.

Thanks for your input!

 

One code was pending or stored and the other was current.

Put "crazy" into the search box at the top of the page.

in the mean time; this is what you asked for

 

We've had a number of members with similar issues. It may be totally cleared, but there are some things worthy of checking. From what I remember, the typical suggestions were:

- check the battery at an auto parts store with a load tester to ensure it is up to snuff (a bad/low battery can cause some very weird issues, including bad shifting, gauges running wild etc.)
- check under the hood for loose/bad ground connections from the trans to near the radiator top support (if I remember right)
- check the under hood fuse box to ensure that the top half is secure to the lower half


How many miles you got on your 2010?

ps: good one Donbrew!!!!!! gonna have to save that one for my records here.

 

First off Welcome to the site! And all the codes and things point towards the fuse box as Don mentions and a dying battery as Whopper says!
Sometimes the battery has a dead cell and can cause this problem.

 

Welcome to the site

Also check connection

 

You may want to read my thread...https://www.chevyhhr.net/forums/prob...-sudden-54847/

And when you check the battery while your there remove the ground connection and clean the terminal and the surface it mates to then reinstall. Pull the fuse and re-seat it.

Mike R

 

Great first hand advice! Thanks Mike!!

 

Great thread guys. My car started acting up with many of these symptoms. I am going to start here and see what happens!!

 

Sure would be nice if people came back with results.

 

The OP seems to be a one and done! No activity after this original post date of 02/20/2016