What are navigational lights?
 

I have a dash light on that the owner's manual says indicates a problem with my navigational lights. Headlights (high/low) are fine. All turn signals are fine. Parking lights are fine. Backup lights are fine. Brake lights are fine. The upper brake light is fine. Any ideas? Or can I supply more info?

The light indicating a "navigational" bulb is out came on in my 86 560SEL when a license plate bulb burned out. Check that.

Side marker lights?

Do you have the extra turn signal light in the fender?

Tail lights?

Maybe you should have flashing green and red lights on the wings:D

I know, being a smart @ss again...

It's all right.....I bet I'm a bigger one.

It turns out I just wasn't observant enough. The taillights are wrap-around and when first checking this problem out, the person was standing behind the car looking at tail/brake/signal lights. Tonight, I went out to check the license plate light when I noticed that the driver's side taillight was lit on the side. I checked side part of the passenger side taillight and sure enough, it was dark.

Thanks, rsmartin....it was your suggestion that got me checking.