Ignition Warning Light - Alternator Problem?
 

The ignition warning light on my 1977 350SL now stays permanently off. The car starts and runs, all instrument guages work and warning light bulb tests OK. Does anybody know if an alternator fault or other failed component would cause such a problem? Is so, how could I test it?

Thanks.

Alternator test
 

If the alternator is bad you'll know it because the battery will go dead in a couple of days of driving.

If you have a Voltmeter, measure the voltage across the battery. Should be at least 12.0 volts.

Start the car and turn on the headlights with brights.
Mearure the voltage across the battery. Should be .8 to 1.5 volts higher than the first measurement.

JV