edtse88

I'm having electronic problems that have been giving me a headache lately. A timeline:
Convenience functions turning off issue. I thought it was voltage regulator
Replaced voltage regulator
New issue shows up, the red battery indicator comes up once in awhile, after driving awhile. Convenience function still shows up. Car starts up fine.
Thought maybe I just needed to drive it a bit to charge the battery but now ABS, ESP error stays on. Cruise control also doesn't work anymore.
Reduced brake function light also comes on once in awhile now, sometimes stays on longer, sometimes just blinks. Also reduces power probably due to the brake issue. I'm assuming its something to do with the auxiliary but I had it tested and they said it was fine even though the guy has never tested an auxiliary battery before.
Also I noticed that my headlights flicker especially on startup.
The scanned codes I am getting are shown below. Before I buy a new relay, what else do you guys think could be the problem? Alternator, BCM, fuses, some kind of connector issue?
The issues seemed to have gotten worst since I replaced the VR, before it was only the convenience functions. Is it something I did?

Cheers,
Ed

rapidoxidation

How old is your aux battery? If it is more than 5 years, put a fresh one in.

edtse88

I'll have to check but it's definitely more than 4 years. I just charged the the auxiliary battery and all the errors have gone away when I drove around for 10km. I also took out the alternator to clean all the contacts. I should have done that when I changed the voltage regulator. We'll see how it goes. I'll report back once I get a chance to run down the auxiliary battery if its not charging correctly.

edtse88

I've driven the car another 1000km now and it seems fine. No convenience function disabled or anything. There was one day where the ESP/ABS/Cruise Control was disabled but it went away after restarting my car.

In conclusion, the initial problem was the voltage regulator but when I changed it, it must not have been making good contact with the alternator. So if you ever change your voltage regulator, brush off any corrosion on any contact points. I just used a brass wire brush.