Just noticed today (only had the car 12 days ) when I switch my headlights "on" the driver side is out but when its set to "auto" (where its been set since I purchased) both sides work just fine..
Does "auto" use a different set of bulbs than "on"?
Do I need to replace a bulb? If so which one?

any help is appreciated

 

Nope. Same bulbs.

 

Any idea on what's going on? Thats strange isn't it

 

If it's a bother, grab a meter and go checking.

 

I would suspect the head light switch. This is in the steering wheel stalk.

Before I changed it and would monkey around with the switch moving it back and forth to see if you can get the head light to come on. Sounds like a contact issue in a multi-function switch.
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That multi-fnction switch is flaky. Mine now flickers on the Auto position works fine in the ON position - sounds like a common type of issue. Not worth replacing.

 

It will be when it causes a battery drain

 

Yes it can cause all kinds of other weird problems so I would get it fixed.

Maybe I should expand on this a bit?

The S Type uses a ground switching arrangement. This means everything is live or hot all the time and the circuit is completed by grounding the circuit. So if the switch is not working right you have voltage running around who knows where.

In the old days the electrical systems worked just the opposite. The power was switched on and off. So if you had the same bad switch you generally would not see any problems until you actually moved the switch to turn something on.
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