I had this same issue after running my wire from the wiper switch to MICU and the INT timing was still constant. I unplugged the switch harness connector where I added the wire on pin #8 and noticed it was not inserted all the way in. Make sure it goes all the way in and that you can see the pin's tip end on the opposite side of the connector just like the other pins that already in there.Hi guys newbie here, sorry for reviving an old thread, but if anyone has done this mod successfully maybe they can shine a light for me.
I have a FD1 (Aus). I have pretty much followed the walk through, connecting the wires to their designated pin slot, checked it with a voltmeter and confirmed there's power through the switch to the MICU. however, the INT timing is still constant. Not sure if the FD2 (Sports version) MICU is any different to the FD1, though I think it wouldnt be.
Tip for adding pin to switch connector: It is easier to insert the pin all the way if you release the white plastic piece backwards from the black connector plug before inserting the pin. Put the white plastic piece after making sure the pin is fully seated on its position.
Tip for adding pin to MICU Connector: to insert the pin all the way, you need pull the green plastic release tab backwards (I used a small flat head screwdriver to separate and release the tab holding down the pins) and then insert the pin on #6 (this was a PITA to insert because you have so little room and the wire going there was so thin that it kept bending and not letting me insert all the way. After you have inserted the pin, put the green plastic tab back to secure the pins in the connector.
One last tip: do a quick pull on the 2 pins that were inserted to make sure they do not come out from the connector and that they fully seated on the connector.