What’s up everyone and welcome back to the channel. In today’s video I am going to share with you one of the biggest issues I have had with my car to date. My car has 77,000+ miles and I drive it in every season. I am calling this the biggest nightmare for every c7 corvette owner because it can happen at any time and can be very dangerous. This can also cost you thousands of dollars if you take your car to the wrong dealer or accept every dealer’s service recommendation.
Every time I would get in the car I kept getting the “Service Rear Axle” notification and I had no idea what it meant, I plugged in my OBD Scanner and nothing was coming up. I noticed that the AC would cut off or perform poorly when that notification came on, but it would bounce back.
Unfortunately, this service message is basically a catch all for “GM” and this worried me because on the corvette forums there was no A = A answer..People’s experience literally varied from a bad battery connection or spark plug, to others having their entire rear differential replaced. I took my car in for service and it was $185 to run diagnostics and they ran all the tests and everything turned out fine.
I even asked about the alternator and they said there were no issues with the alternator. However they figured out that the rear differential control module needed a calibration update as well as trying to charge me on an engine coolant flush. They later called me back and told me that the control module was bad and that it needed to be replaced for $1310 and that it would take 10 days to get in. Keep in mind I was not getting any check engine lights or experiencing any issues behind the wheel.
I had a rally at the end of the week and I wanted to know if my car would be okay to drive. They said that it would be fine and that they could do the service when I returned.
This is where it all changed. So fast forward to my rally, I am cruising with the group and we are on the twisted sisters which is one of the most notable canyon roads in all of Texas. We are heading west out of Boerne and on a huge sweeping corner my Stabilitrak light starts flashing. I can literally feel the back end of the car starting to shimmy around the corner. So on every corner my car now wants to shake, giving me no confidence at all. I scrolled through the performance setting on the gauge cluster and went to the rear differential screen. Normally there is a percentage number on there and now it was just dashed lines. I knew this was not a good thing so I slowed way down. Fortunately for me this trip was just constant rain and horrible weather so speed wasn’t a factor.
I had a surprise rally for a close friend towards the end of the month and I knew I wanted to get my service rear axle message resolved. I had them replace the rear differential control module and the message was no more. About 10 mins into the trip the following day I was sitting at the red light and the Service Rear Axle message came back on. I was really upset. I learned that it wasn’t constant like it was the first time because we pulled over and filled up for gas. After starting the car the service rear axle message didn’t pop back up and my screen was showing a percentage on the differential.
So now I knew that my car was either hit or miss.
If I got no message on the startup I had 100% confidence in the vehicle
And if I got the service message it meant that I had 0% confidence.
So for the rest of the trip I basically left my car on when I could, or I would slow down so I wouldn’t crash. This was frustrating and as time went on and the hotter the car got the higher risk I had of the light coming on.
So I now knew that the differential most likely wasn't the issue since it was hit or miss; During the rest of the trip I kept switching back and forth from my differential screen over to the battery voltage gauge. On this gauge it would range from 13 to 15 which I thought would be normal for the most part considering it was 90 degrees in Texas and my AC was full blast.
Once I got back into town I took my car into the dealership and told them to check the voltage spikes on the alternator and replace the alternator. They took a few days and had to contact the corvette engineers at GM to confirm that this was the fix. I was really upset when the dealership wouldn’t reimburse me for the control module. They said that the voltage spikes from the alternator fried the original control module. I guess I am lucky the second one didn’t fry as well.
