In that they only work (when you cover the sensor) when one of the overhead interior lights is on or the door is open ?, anybody else experienced this or have any thoughts, I have installed a GT3 seat on the drivers side but correctly reconnected the control box beneath.

 

Richard,
This is a shot in the dark but I will try.
Any chance the upper seat part is not blocking the sensor eye in the mirror? I know the seats are wide and high in the top portion, just wondering.

Bajo

 

but you can completely obsure the sensor with your hand which should dim it but doesnt

 

Richard,

By obscuring the sensor you are blocking the light and therefore it is sensing there is no bright light and will lighten the shade.
Try taking a flashlight and shining it towards the sensor and see if it gets the mirror to darken. If that does work (with the flashlight) then I am going to say everything is working as needed, if it doesnt than you have a bad sensor which is housed in the mirror assembly.


Bajo