Originally Posted by spearfish25

Alright gentlemen,

This post could go in a number of places but we need a bit of high profile traffic to get this figured out. Our car has all the hardware to get the rear fog working except for the control yolks with the switch. Essentially, the rear fog is wired all the way up to the BCM which takes input from the Combination Switch. The BCM is located in the passenger footwell (outer side). The Combination Switch location is a mystery to me, but may be incorporated into the BCM.

Here is what I'd like to do but need help. The combination switch reads combinations of inputs and outputs which alters a signal sent to the BCM. Based on the signal changes, the BCM activates/deactivates various systems. To get the rear fog turned on, we have to close the circuit between Output 3 and Input 5. This corresponds to terminals 5 and 13 on the M33 connector.

Can someone with some know-how confirm this and comment on whether splicing a switch between the terminal 5 and 13 wires would give rear fog light control? If we make this work, we can move the thread to the DIY to give people a wiring option that uses the factory wiring and avoids wire runs through the back of the car.