Purchase a 2003 S Tupe 3.0 Manual a month ago.
The radio functions normally along with steering controls on the ignition first step (engine is off) and once i start the ignition, the radio controls go crazy and the steering wheel volume buttons both reduce the volume the CD track changer increase the volume and the mute button keeps going off and on by itself!
Any experience with the above?

Thanks

 

I know it sounds daft, but check your battery connexions are not suphated or loose-ish. If they have been greased, sulphation is unlikely. If you can't rotate them by hand no matter what force you use, probably ok. All easy and free to do. If after checking you suddently find the engine cranks faster, you've had your hand on the problem! Otherwise wait for a knowlegeable contributor with specialized info. on this one.
Leedsman.

 

Is it a factory original stereo?

If not, then someone probably installed an interface adapter between the aftermarket stereo and the steering wheel controls connection.

I have yet to get into that adaptation myself, but its my understanding that some of them use some kind of infrared communications method that is interfered with under certain bright light conditions (sun roof open, bright sun).

If its not the infrared variety, then it may still have something to do with that interface, bad connection(s)?

 

If the wiring hasn't been messed with, Leeds is probably on the right track. These cars (complicated luxury cars so BMW and Merc included) are known to act crazy as the battery starts to go. Don't rely on the old school tests. It could still start the car but make all kinds of other things act up.

 

In fact the battery was replaced and it all fittings are perfect, alternator was changed as well.

The Radio was replaced by the dealer who sold the car, replaced with an original one. I checked the connectors and it sill does the same thing. Works fine until the engine starts!

Thank you all for your thoughts

 

The steering wheel controls change resistance across a circuit, I cannot imagine what could cause what you describe, except possibly the charging system.

Thats the only diff between switch ON, and running.

Switch On is battery only, but when running, the alternator takes over.

 

I guess a chafed wire or loose connector might act differently due to the engine vibration. Er, maybe?

Oh.... or a chafed wire that touches another wire that's not live until the engine's running. Plenty of those

 

Yes, we will start drilling into it with my mechanic, he is convinced that it is a good car but we need to trace these issues. It is now isolated to the alternator and everthing else LOL!