The ground is very important on these things. Also it is the best to have it installed as close as possible to the window switch because the longer the wire the bigger the resistence so the FORD module can malfunction. Some cars have ground on the door panel and some don't. My car has a solid ground on the door panel. My instructions say to look for a good solid ground !
Thank you for the heads up Sagittaria !!
Thank you for the heads up Sagittaria !!