Rear Differential error

[Poltergeist]

Leaving home this morning I got about 2 blocks away and the DIC popped up Service Rear-End, or something along those lines. I pulled over and got to the Diff screen and have the below. I took the car back home and left it there and drove my truck to work instead. Any ideas??

I don't know if it might have anything to do with the issue but last Nov a piece of metal flew around the inside of the driver rear wheel well. I looked for damage on the inside of the wheel well while the cover was out but never saw anything.


This was taken when the car was in the garage and not moving.

[c4c5specialist]

HI Rob,

Check to see if ONSTAR has a diagnostic trouble code out of the eLSD module or have it scanned.

Check to confirm the last time the fluid was changed, we always like to have them changed after the first year and every 24k after that.

I have seen metallic sheen that is classified as normal so dont be concerned. I just feel the correct clutch apply is a direct relation to fluid quality.

Also, assure that if the code is C0407, you reprogram the differential control module with the latest calibration.

Confirm your tires are within 1/32 of each other tread depth wise.

Allthebest, Paul

[Poltergeist]

Almost 6 years old so more free Onstar. Would a scanner from Autozone be able to pull codes?

The fluid for the rear has never been changed. Unless they did it during the triple flush of the transmission. The dealer never mentioned doing it that I remember.

Will have to check the tires but they should be close as they were replaced new end of Sept and the driver rear was replaced end of Nov after the incident. Looks be about 6k miles difference.

[Poltergeist]

The code reader from Autozone didn’t read any codes. Looked under the car and saw no loose connectors or anything out of the ordinary.

Would low diff fluid cause this? Is there a sensor for that?

[Poltergeist]

One thing I did find was that negative terminal of the battery was corroded. I cleaned it off and put it back on. When I took it for a test drive I still got the Service notice.

When I went out a few minutes ago and started it to see if the battery was charging, looked to be about 14.4 volts, I did not get the service notice with the car running and sitting in the garage (the garage door was open so don’t worry). When I looked at the differential screen it now has 0% at the top instead of —-% I put the battery tender on it to let it charge overnight.

[c4c5specialist]

HI Rob,

No OBD2 scanner will get your codes. This would have to be done at a GM dealership.

Yes, noone I know really talks about the rear differential fluid, but I have seen nasty stuff but GM considers it normal.

Get the code and we can help further.

Paul

[LLC5]

Almost 6 years old so more free Onstar. Would a scanner from Autozone be able to pull codes?

The fluid for the rear has never been changed. Unless they did it during the triple flush of the transmission. The dealer never mentioned doing it that I remember.

Will have to check the tires but they should be close as they were replaced new end of Sept and the driver rear was replaced end of Nov after the incident. Looks be about 6k miles difference.

6K difference is a fair distance with soft tire compounds, measure the middle and both outer tread depth areas on each rear tire, you may have more than 1/32" difference. Outside rolling diameter is hugely important with newer vehicles and their computer coded parameters.

[Poltergeist]

This is seeming more like an electrical issue. I drove the car to work on Sunday. Drive there fine no errors. Leaving work I get the Service Rear Axle error, but this time the DIC started flashing. When I dismissed the notice the DIC stopped flashing. For the first 35 miles or so of my drive home I watched the battery go up and down like a roller coaster from 13.1 to 15.3 and back down. After 35 miles it seemed to settle down to 12.4 except if I had to hit the brakes and then it would go back up to high 14s and low 15s and back down. Battery was replaced Nov of 2019, Alternator was replaced Dec of 2019. My bet right now is the alternator. I've been told that Autozone can test the alternator and battery with them in the car so I'm going to check with my local one and see what they say. I'm really hoping a control module is not on its way out but will have to see.

[c4c5specialist]

HI there,

I would also check your connections at the battery.

Sounds to me like the ground eyelet might be loose or the terminal itself.

Allthebest, Paul

[JB]

Rob i know very little about this but i also did not take onstar after the 30 day trial. I had an error code on my c8 and i called onstar and they still gave me the code number (i might have onstar coverage even though i chose not to pay)

If it were me Rob...i would consider changing the fluid in the differential ...ive also had a situation where the battery registered fine but we changed it out and low and behold on my last corvette the corvette issues were resolved..

Corvettes are very challenged with voltage shifts and batteries can have that happen before their replacement date.

Try the ground issue and other suggestions Paul mentioned first. He knows best. Im just shooting from the hip.

Good luck and let us know step by step what you found resolved the issue.

[Poltergeist]

I have sent the alternator back for a replacement. If that doesn't fix it I will try the battery. Will check the battery connections again this weekend. Thanks everyone.