If its right after you turn off the key it might be a power antenna motor.
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A humming noise from behind the dash of a 2001 Saab 9-3 could be caused by a malfunctioning blower motor, which may be struggling to operate due to wear or debris obstructing it. Additionally, a failing actuator or a problem with the climate control system could produce similar sounds. Electrical issues, such as a loose connection or a failing component, might also contribute to the noise. It's advisable to have a mechanic inspect the vehicle to diagnose the exact source of the issue.
All you have to do is put your key in the ignition and turn it not all the way to start but to where all the electronics work and the lights on the dash light up. Listen for a humming noise behind you toward the trunk. If you hear that humming noise for a second or two then your fuel pump works. Check your fuel filter and or injectors they may just be dirty.
A clicking noise from the dash on a 2003 Mercedes Benz might be the flasher for the turn signals. Sometimes the flasher will make a clicking noise if it is about to go out, to let the driver know it is time to replace the flasher relay switch.
Buy a piece of black fuel line hose from Lowe's or Home Depot and cut it to the width of the dashboard. Push it between the dashboard and the windshield all the way across the width of the vehicle. Hopefully this will take care of your noise!
Ford Dealer can help you. And tell you if there is anything wrong with your 2003 F150.
Behind the glove compartment on the dash.
Behind the fuse panel that is on the drivers side of the dash.
could be the water pump. maybe radiator
was there something on your dash that fell in the vent, a bad fan will make noise all the time.
Behind the fuse panel in the driver's side dash.
Behind The Dash Underneath The Steering Wheel , Slightly To The Right.