Why is there a fuse in the fog lamp socket when the vehicle does not have fog lamps?

The short answer for this is that GM did not determine if the vehicle was going to get fog lights or not based on the fuse panels.

Basically, they built all the fuse panels the same and then if the vehicle had the lamps, the wiring, fuse, and relay was there. If it didn't get them then it didn't have the lamps.

I don't know if this to be true but more than likely the harness is the same and there are fog lamp connectors taped in the harness behind the bumper.

GM did not want to make separate parts for each different option as that would require a different part number and cost more money.

If they make them all the same, then the supplier would charge them less as it is easier to make all one part rather than a different version of the same basic part to fit each differently equipped vehicle.

If they can save $5 dollars on a each harness that adds up to hundreds of thousands of dollars in savings by the time they are done with buying all these parts.

I attached the wiring diagram that will help illustrate this as it lists fog lights as well and is not shown in a separate section. This means they all have this but may not have the actual lamps.

Hope this helps.

Thanks