jjuliano

I installed a new battery today and now I am having a few strange issues. There is a - and degree symbol but no outside temp showing up on the infotainment screen. I am also getting a service rear axle message. The fob trunk release is also only working intermittently. The small wire got separated from the main ground terminal but I reattached it. Has anyone had similar issues after changing their battery and if so are there any insights? I was hoping to avoid a trip to the dealer.

jaki30

Is the small black wire reattached. with a soldered or crimped joint?
Try disconnecting the negative battery cable for a couple minutes
and see if that resets everything.

eboggs_jkvl

You probably have a loose cable on the battery. It MUST be aligned the same as it came from the factory and it must be tight. This is the usual gremlin for a battery change.


Elmer

Vetteman Jack

I agree - check your battery connections and make sure the thin black wire is attached tightly.

C7_Craig

I had my battery unplugged for about 2 hours recently while doing some work on the car. Upon driving the car there were 3-4 gremlins that worked themselves out after about 10 minutes of driving. My radio wouldn't turn on, the rear hatch outside pop button wouldn't work and my passenger side hood refused to catch and latch. Strange. But before I made it out of the neighborhood the systems had found their legs and recovered to normal status again. (Assuming your battery connection is attached correctly).

BAT

I changed my battery a few weeks ago, and had a few issues too. It took a few tries, but I finally figured out that one of the positive connections wasn't super tight. I really had to crank it down. Once that was done, I had a few codes and the CEL was on. I did the usual 10-12 start and heat cycles, then they eventually went away. It's been fine since without any codes or CEL.

jjuliano

Thank you for all of the suggestions and insights. I will try a number of these later today and post the outcome.

jjuliano

I went back and tightened all of the connections. One of the connections on the positive terminal was not tightened all the way. The car started up and I got “top not secure” and “open and close driver side window”. I lowered and raised the window and pushed the top button to up and heard it reseat. Additionally the trunk still would not open with the fob or the interior release. I took the car for a ride, shut it off and restarted it. The trunk now opens with both the fob and interior release. Fingers crossed that the issue has been resolved. This whole experience makes me miss my C5. Battery replacement was so much simpler. Thanks again to all who responded!

eboggs_jkvl

Blasphemy! The C7 kicks the C5's donkey!

Sounds like you got it. Those cables need to be exactly aligned as they were from the factory and TIGHT.

Enjoy the drive.

Elmer

Rabbi

Because of all the threads on this subject I will always pay the dealer to change the battery.

jjuliano

Thanks Elmer! Simplicity in working under the hood is the only thing I miss about the C5.

jjuliano

I tend to agree with you. However I changed the battery in my ‘17 Cadillac and my wife’s ‘18 Benz with similar complexities with no issues. Step by step videos are available on you tube. The C7 seems to be more complex though.

Factoid

I recently changed the battery in my C7 and fortunately had no issues. That said, I also changed both batteries in my Jeep Gladiator. This is not for the weak! To get to the smaller battery under the fuse box, you have to remove the fuse box and pull out all the cables that connect to it. It was scary.


You have to remove the main battery outlined in green, then the fuse box outlined in blue, then pull all the cables aside that plug into the fuse box, and finally remove the aux battery cover to access it. Putting it back together was harrowing!

eboggs_jkvl

Oof! Don't want to have to do that. Looks like a real PITA.

Elmer

dbirdhouse1

Leave it to the mechanic and when dealing with battery issues, I and others have had the "service rear end" message come and go away on its own........

Skid Row Joe

Sounds good! The C7 is "self-healing." I love that about it. But to re-want the C5? I'd stand pat with the C7.

jjuliano

Yikes! That one really took some guts. Not sure I have it in me to pull that one off. I’m glad it worked out for you.

jjuliano

I only miss the simplicity of working on the C5. I love the C7. I also learned a thing or two about its self healing properties too. 👍🏻

Raggaemon

I've seen the same "Service Rear Axle" warning for sometime now. I've taken my C7 to the local dealer twice, they examined the rear axle but didn't find anything mechanically wrong. They also checked the wire harness from front to back, two clips were found to have small amounts of corrosion, which were replaced, there was also an intermittent short found at the battery cable connectors, both were replaced.

The warning still shows-up after I've driven my car a few miles, pressing the "SEL" button on the steering wheel clears the message, but it pops up again if I park and restart, it shows-up only after driving a few miles. I've tried detaching and reattaching the battery cables, ( replaced the battery 2 years ago, not a daily driver), I've tested the battery voltage. The dealer thinks that this might be caused by a tune which was done a few years ago, they think the tune could have triggered a glitch causing a phantom code, there's no CEL, thankfully?

Any suggestions, I'm planning to sell my C7, can't with this warning.

Citation

I guarantee all the discussion above is the small gauge black wire. I recently had the service rear axle message which also causes stability system to engage with moderate cornering. My black wire looked fine and I had previously changed the connector a year ago.

This latest issue we cut off the wire and soldered a new connector. All problems gone. If there are any broken conductors in that wire or any resistance in the connector you will get all these and other issues.

Cut off the wire an inch or so, properly solder and heat shrink a new connector. Done.