How do I link a light control through a vehicle seat?

Hey, I am trying to script the headlights on a school bus. I have buildboard GUI's as the lights. I am using key inputs ("L") for the light block. It's in a local script in the vehicle seat, why do my lights not work?

--[[
Light = Buildboard GUI
"HL_" = Headlight
"BL_" = Brakelights (4 of them)
"Engine" = The model SOME lights are in
--]]

local mouse = game.Players.LocalPlayer:GetMouse()
function onKeyDown(key)
    if key == "l" then
            script.Parent.Body.HLL.Light.Enabled = true
            script.Parent.Body.HLR.Light.Enabled = true
            script.Parent.Body.Engine.BLL.Light.Enabled = true
            script.Parent.Body.Engine.BLR.Light.Enabled = true
            script.Parent.Body.Engine.BTL.Light.Enabled = true
            script.Parent.Body.Engine.BTR.Light.Enabled = true
        else
            script.Parent.Body.HLL.Light.Enabled = false
            script.Parent.Body.HLR.Light.Enabled = false
            script.Parent.Body.Engine.BLL.Light.Enabled = false
            script.Parent.Body.Engine.BLR.Light.Enabled = false
            script.Parent.Body.Engine.BTL.Light.Enabled = false
            script.Parent.Body.Engine.BTR.Light.Enabled = false
    end 
end
mouse.KeyDown:connect(onKeyDown)