So first I noticed that my aftermarket sunroof stopped working. Turn the engine on (instead of just being on ignition) and it started working again.

While driving, turned my headlights on (after being in the parking light position), and everything worked but my stereo turned on and off.

Then I noticed the battery voltage gauge moving slightly and waving up and down instead of sitting constant how it normally does.

Then I turned the interior light on and it was working but flickering (which was coinciding with the battery voltage gauge moving up and down).

Then when I turned the car off, the sunroof didn't close (as it normally did when I would turn the car off).

Other than that, everything electrical seems to be working. Any ideas?

 

Earth lead connection @ the chassis ( bolt beside battery tray.)
Maybe a large wattage draw will make the connection enough to start the car, from then on it might be running off power from the alternator, hence the flickering interior light & stereo..

 

Thanks for your response. It turned out to be a battery acid buildup on the battery isolator switch that I had installed.

Once I removed the battery isolator switch, everything was ok. So does the flickering interior light indicate that the car is running off alternator power?

 

Yep, i think so. The bad connection was letting thru enough power to start your car, but once the power use dropped down, the power from the alternator was taking over the job of powering the car. Since the amount of power a alternator puts out is regulated by the amount of power thats being drawn out of it, its output is constantly changing.
T​​​​​​he battery ( a accumulator ) then acts as a resivour and averages out the power going to the lights & everything else.
Without the battery being in the electrical circuit, the alternators putting out a constantly changing amount of power & the lights then flicker.

I have had a similar problem with trying out LED bulbs in my numberplate lights, the LEDs simply didnt draw enough power to make a decent connection & they would flicker & turn off.
Cleaning the connections on the LEDs didnt help stop it from happening, but when i changed the lights back to a tungsten bulb sort, they worked properly. The weak connections were the switchs & such, without the a decent amount of power going thru them, they just gave up.

The other thing that i noticed was that my ( stock Audi brand ) stereo was not turning off properly when it was switched off.
Since I fixed the earth lead connection, the stereo is now not making any sound at all, though its turning on & off like it normally would. It might have blown the amp inside it, i will check this out soon.

The speakers are not making any electrical interference sounds any more.
The cars engine seems to be running smoother now, not missing anywhere as much as before while idling.

A​​​​nother thing was, i had a different stereo in it a few weeks ago, betore the earth lead problem appeared, and its amp heatsinks were extremely hot, scortching hot, too hot to touch.

i now think that I can add 'Remove, inspect, clean & reassemble the Earth lead', as a job that has to be done on every Audi i ever work on again. Before I do anything else to it.

 

Learn something new everyday... Makes sense though.

Anytime I'm working on a car with flickering interior lights I'm going to think that the alternator is powering the car.