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			The fog lights on the 986s ARE halogen.  Now if you actually mean replacing a halogen with an appropriate LED replacement, there is no issue.
 If you are talking about replacing an LED with a halogen in an application designed for an LED, which is not applicable to a 986 as I mentioned above, then yes, there is an issue.  If a the application was designed for an LED, it will not be able to power a halogen bulb.  LEDs use much less current and have control circuits designed to limit the current to the LED and the enclosure will not be designed for the heat of a halogen bulb.  LEDs in lamp assemblies _designed for LED_ are generally not user replaceable as their MTBF (mean time between failures) is high enough that it is basically a lifetime "bulb".
 
 A little more information would be good.  What are you trying to do?
 
 
				__________________'03 S, manual, 18" Carrera wheels, PSM, PSE, Litronic, 996 Cluster, +
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