Multiple Codes / "Phantom" Problem
#1
Multiple Codes / "Phantom" Problem
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.
Thanks for your input!
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.
- What difference does it make that there were two P0700 codes?
- Do I need to check or poke at anything, knowing that the problem seems to have gone away completely?
- 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!
#3
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.
- 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.
#4
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.
Sometimes the battery has a dead cell and can cause this problem.
#6
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
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
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