various thing 99 S Class
 

Need to know what a steering angle sensor does when its bad,also when a alternator gets bad.Lets say not charging good,and no check engine light,does it kill the engine at idle like a Dodge?

On other cars I've had issues with steering angle typically disable the abs and the traction control. But I've never owned a 99 S320

Ah then I'm ok cause Ive delete abs and asr

To answer your alternator question, typically the voltage regulator goes first. I have had this happen on my twice on different cars, without getting the battery light. The voltage regulator limits the output to the battery, from the alternator to about 14.5 volts. It's real easy to check the condition of your charging system. With the car off, the battery should read 12.5 volts. Once started, it should read 13-14 volts. Rev the engine and it should stay the same. Any spikes higher than 14.5, means you most likely have a bad voltage regulator. If the volts don't increase from 12.5, then your alternator is not charging the battery.