Here is my response, posted last night, but not "approved" yet:
The Alfa 4C has 5 toggles, 3 of which activate the door locks, AC and demister in US cars and a fourth toggle which operates a rear foglight in some other markets. I wished to activate the immobile and unused toggle(s) and an earlier post suggested it was possible by a knowledgeable technician. It and not difficult but two caveats are clear: 1- The existing electro-mechanical toggles operate momentary switches, not on/off toggles. The circuit board that supports (and is housed in the same black plastic case) converts the momentary pulses to on/off and this board was multilayered and too complex to trace out the unused circuits that support these switches and pinouts. 2-My solution was to cut the unused miniature momentary contact switches from the circuit board, carefully solder leads onto them, tailing the leads out through a hole drilled in the back of the case, and superglue the switches back onto the board in the exact same place.
How to: Remove the cover plate underneath the switch assembly and remove the four screws (2-phillips, 2-star-point “security” screws). Separate the toggle assembly from its harness and remove the assembly, housed in the black case. Carefully remove the two small star-point screws on the back of the case and pry the five locking tabs free, being careful to not damage them. Remove the back piece, with the circuit board that held in place by posts and set aside. Photo 1 shows the circuit board with its 5 orange momentary switches and the remaining switch housing with its light-gauge metal “tabs” in place. Carefully remove these tabs to reveal the toggle mechanism. Photo 2 shows the existing toggle handles, which must be removed. Insert a flat-bladed screwdriver between the back of the toggle handle and the plastic face and carefully twist the screwdriver to remove the toggle handle from its base. Protect the plastic face with, wrapping the blade tip in cloth, to avoid marking the face. Photo 3 shows the length of the “arms” of the toggles and the entire switch assembly disassembled. The back of the toggles use a “horseshow” mechanism that operates on two pivot points. Photo 4 shows the “horseshoe” and the pivots. Carefully pry back the two “ears” of the pivots enough to remove the “horseshoes” of the toggles you wish to activate. Note that the working toggles use a white nylon slide which freely moves under a “horseshoe”; the immobile toggles use a black plastic slide. It is possible, with modification, to use the black plastic slides but they must first be removed, filed down and re-installed. Photo 5 shows a slide and the tools I used to remove them: two razor blades and a drift. Wiggle the razor blades (or two small jeweler screwdrivers) into the space where the slide meets the holder so that the slide is “released.” Note that each slide is held in by only one tab in the middle of each side of the slide. Use the drift and a small hammer to carefully tap out the black slide. It is now necessary to file or gently sand down the thickness of both sides of the slide to allow it to easily move in the switch housing or assembly. This may take several attempts; I probably flat filed 20% of the total slide thickness away. Install the slide and remount the “horseshoes” previously removed. Now comes the “hairy, technical part”: removing the unused one or two momentary switches from the printed circuit board.
I used a razor blade, carefully cutting the switch from the board but also being careful to leave enough of the switch leads to solder two leads on the switch, diagonally opposite each other. Superglue the switch back onto the board in the same location it was previously. Be careful to isolate the switch leads from the circuit board and its traces. Drill a hole in the back and tail the leads out – see the final photo, the sixth in the series. Re-assemble the tack being careful to replace the metal strips in the respective locations. I tested the complete assembly with an ohm meter for the switches I altered, to insure each toggle would momentarily operate (close) the contacts on the appropriate switch. Then, re-assemble the toggle arms noting the depressions on the toggle face up. I soldered a micro connector on the new switch leads and inserted this harness in the space between the radio and the switch receptacle; the micro connector allows me to remove the switch assembly by unplugging the original harness and the new one. Plug the original harness into the existing receptacle on the switch assembly, slide the completed assembly into place and insert the four screws used to hold it in place, tightening each as appropriate. Note that the two star-headed screws have a tab-type nut that can be jostled out of place. You are now done and everything should look and work as before, except that you now have 1 or 2 extra working toggles that operate momentary on-connecting switches. I will use one for a momentary control operating a forward-facing video camera. A Schottkey diode isolates the 12v line from the backup lights when the front-facing camera and monitor receive 12 volts from the momentary switch. BTW – I replaced the irksome Parrot radio with a single DIN Kenwood KIV (901 or 701) radio that slides into the slot, looks factory and has a small LCD screen and camera input. Several inexpensive Asian alternatives also work in place of the NLA Kenwood.
(pictures to be re-posted, if necessary) st