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Hi guys.
i have just replaced the battery with a new one, and i have started notice issues of low voltage (A/C problems, occasional screening flickering and some messages like "Service rear axle" often come in.
the Voltage on the display was oscillating from a max of 14.9v at starup until a lower value of 12.5v while driving.
So i replaced the alternator, same identical isssue.
basically new battery and new alternator haven't fixed it.
any tips?
I'm not an expert, but those voltage numbers you mention are normal. I know that for sure. Mine runs at 14.8 or so for the first twenty minutes and then settles down to 12.7. That was also true on my previous C7.
I'm not an expert, but those voltage numbers you mention are normal. I know that for sure. Mine runs at 14.8 or so for the first twenty minutes and then settles down to 12.7. That was also true on my previous C7.
Hi
Usually A/C glitches and "Service rear axle" are clear messages of low voltage
Start up your car, and disconnect your positive battery terminal. If the car dies you have a bad alternator. If it doesn’t your alternator is fine. New stuff doesn’t necessarily mean 100% working condition.
As others have mentioned those voltages are normal
You need to find somebody with a GM MDI and GDS2 software and have the individual modules and the MDI bus scanned
One funky module or bad connection can play havoc with the BCM and ECM . I am confident you will find something in the history
Normal inexpensive scanners will not scan the individual modules
Check and double check all the cable terminals on the battery board. I had similar "service rear axle" and actual sporadic engine flame outs. Found one of the 100 amp terminals just a tad loose and it would apparently lose contact now and then, like twice a week or so, and give me these issues. The one indicated by the red arrow was the problem. Snugged it up and all is well.
Start up your car, and disconnect your positive battery terminal. If the car dies you have a bad alternator. If it doesn’t your alternator is fine. New stuff doesn’t necessarily mean 100% working condition.
Never disconnect the battery while the engine is running! This is not a valid test!
It can instantly damage the alternator and or other electronics.
searched and found this thread. i got my c7 a couple months ago and noticed the same voltage and it freaked me out. car ran fine but my battery died last week and i changed it out. now i see between 12.8v and 14.8v. seems like under load its in the 12s and when you let off and come to a stop it gets up into the 14s. i guess if these numbers sound normal i will continue to enjoy the car.
searched and found this thread. i got my c7 a couple months ago and noticed the same voltage and it freaked me out. car ran fine but my battery died last week and i changed it out. now i see between 12.8v and 14.8v. seems like under load its in the 12s and when you let off and come to a stop it gets up into the 14s. i guess if these numbers sound normal i will continue to enjoy the car.
The voltage values alone are not unusual. I see 14.8 volts after starting, stabilizing around 13 volts, but if it were my car and I was concerned, I'd do an electrical system check with either a system checker or take it to a GM dealer to have a system check done...
Low voltage issues.
