Getting ready to install a F900BT, the unit came out of a friends car and he had it installed by a shop and removed by them before he traded in his truck. I was looking over all of the wiring last night and noticed something wierd. The shop used the traditional bypass however they grounded the radio to his radio harness ground, the two bypass wires they ran to a toggle switch and grounded it to metal towards the bottom of his dash leaving him access to the switch.

Anyone know the point of the switch? Is there a reason I would need it? I first thought it was there in order to disable to bypass returning the unit to the way it should function but if you were to turn off the switch killing the ground the unit would never think it was parked as the e-brake wire is not hooked up to the e-brake.

It's somewhat of a "safety mechanism", where you can disable the bypass in the event of an inspection/being pulled over/etc.

By removing ground from the parking brake, it thinks the parking brake is disengaged and will lock out functions that normally aren't allowed while driving.

Thanks, thats what I figured it was for. I think I am just going to ditch the switch and wire it up with the bypass normaly. There is already enough wires floating around back there the last thing I need is another one.