Good morning

I have searched the forums looking for possible similar codes and have found some help about checking battery and grounds. I am the original owner of a 2006 2LT HHR and I have been having these same issues off and on for probably 5 years, but recently it had been happening much more often. Usually when that happens I know it is time for a new battery. So about a week ago I put in a new battery and it seemed to work for a couple of days. The old battery was just over 5 years old and usually when I put in a new battery the symptoms and codes go away but not this time. I thought it might be a bad new battery so I had Autozone switch it out but that didn't help. I put a new alternator on last year to replace the original so it is a year old. I have had the switch recall replaced probably 10 years ago. I have not had the power steering motor replaced. The codes I have right now are P0575, P0700 and U0073. My wife just called me and she is sitting because when she starts the car all of the gauges are jumping around, check engine light is on and the transmission is shifting very hard. The gauges have done this before and It seems like it always has something to do with a low battery but this is the second new one. It could be the alternator but when I checked it yesterday it was charging at around 14.5 volts or amps I can't remember. The battery volts sometimes show only 12.3 but they did a load test on it and it was good. The HHR has 180,000 miles on it and I have done most all of the maintenance myself so what do you think. Could the alternator be going bad after a year, the original lasted 13 years. Could it be the power steering motor drawing current from the battery. The TCM although I haven't quite figured out how to check plugs on the TCM yet. I would appreciate any thoughts. I am a long time member and I have tried to search and while I have found similar situations there doesn't seem to be a certain fix. Thanks for any help.

 

Ok. so my wife made it home with HHR. The gauges stop jumping around and all the warnings disappeared after she waited about 30 minutes. The Check Engine Light is on but it is running fine after sitting in parking lot for 30 minutes. I checked the codes again same ones with 2 new ones. C0550 and U0121. I have a OBD code reader that will also check alternator and battery. It shows the battery to be good BUT when I checked the alternator it said the Charging Voltage is above acceptable limit. It is hot in Charlotte 85 degrees but the voltage reading came back as 14.83 volts. Normally I get a reading of 14.5 volts. Do you think the year old rebuilt alternator could be going bad. I also found the posts by CJ and Don Brew. Issues are similar but not the same.

 

12.3 volts is a dead or damaged battery.

You may have a parasitic drain, causing battery voltage to be low until the alternator charges it up. Or perhaps the starter is using so much power to start the car, that the voltage is low for awhile after starting.

 

The issue is not after it starts it is that if you just turn to key on before you start the gauges are jumping all over the place. It starts just fine. This is the second new battery and it checks out good at AutoZone. Right now I am headed to AutoZone to get the alternator checked. If it is over charging the battery that could be a problem. I will report back. Thanks for the feedback. I appreciate it. I am also going to start checking grounds and plugs but that will take a while. Right now it is starting up fine again so I get the feeling it is something electrical but I do not get a battery warning light or charging system light but I don't know how much to trust them.

 

I’ve read on other GM sites that the P0550 Code was resolved after the front hubs were replaced.
https://www.cobaltss.net/forums/www....d.php?t=327230

P0575 could be a faulty cruise control switch

https://www.obd-codes.com/p0575

Now I would test these items first, to determine if replacement is warranted.

 

Ok, so back to the parasitic drain. The battery can be too discharged to operate some systems properly, but have enough power to start the engine.

The underhood fuse block halves could be loose, this causes electrical problems. Sometimes the bolts seem tight, but need to be tightened further. Press down on all the fuses and relays also.

 

The HHR alternator (actually it's a generator) does not have it's own voltage regulator. That is controlled by the ECM or PCM. (can't recall which)
If your charge was showing 14.83 volts, that is not overcharging by Chevy/HHR specs. The charge range is very broad on the HHR system depending on voltage, demand and load. Could be up in the +15 volt range under high load conditions.
Beware of the Autozone test. They're going to test it with a "one" spec fits all tester.

 

Thanks so much to everyone for responding. I appreciate all of the feedback. I understand about auto zone but I just got back from there and they said everything checked out, battery, starter and alternator. I appreciate the information about the generator/alternator that puts my mind at ease a little bit since my tester said 14.83v. I have hesitated to take it to the dealership so far just because I have worked on cars all my life but the computers are something else. I am putting the HHR in the garage and I will start to look for things. It is interesting that you mention the front hubs. I have never changed mine out in 180,000 miles and I think I am hearing a little noise, I thought it might be the tires but I got 4 new tires yesterday so I guess I can look at the front hubs and bearings. It is running perfect right now for me but as soon as my wife takes it out it seems like it acts up with all of the gauges jumping, fast idle so thus rough shifting. If it sets for 30 minutes it fixes itself and runs fine. Thanks and I will start investigating based on a lot of of threads.

 

Yes, that is one of the first things I did, but I may need to pull it apart and look.

 

Yes, that is one of the first things I checked and it was all good. I don't want to pull it apart but I may have to.