Our 2003 Ford Excursion is equipped with a Reverse Sensing System. Some people also refer to them as a parking sensor or backing sensor. We purchased this as a project vehicle knowing it had a few issues that needed resolved. This was one of them.
The Reverse Sensing System (RSS) has sensors in the rear bumper that emit a signal to determine how close you are to things when in reverse, and begins to beep when you get close to something. The closer you get, that faster it beeps. When you got approximately 10-inches from something, it emits a steady tone.
(Reverse Sensing System Sensor / Parking Sensor)
When our Excursion was placed in reverse, the RSS didn’t beep, and the on/off switch for it switched to off every time the truck was in reverse.
The switch shown above is used to shut off the RSS. This useful when you have a trailer or something attached to the rear of the vehicle falsely triggering the system.
In our Excursion, the Reverse Sensor System would shut itself off when the vehicle was placed in reverse. This is because the system senses a problem and shuts it off.
Diagnosing The Problem:
Diagnosing the system is fairly easy.
1)Set the parking brake or chock the wheels so the vehicle can’t roll.
2) Turn the key on, but don’t start the vehicle.
3) Place the vehicle in reverse (engine off).
4) Go to the rear of the vehicle and place your ear near the sensors.
5) Listen for a clicking noise. If you can’t hear it, place a finger over the sensor and see if you can hear it.
The bad sensor will be the one that isn’t clicking.
Prices can vary on these sensors. I actually purchased mine from ebay:
2 Pieces NEW FORD REVERSE BACKUP PARKING SENSORs 4F23-15K859-AA 3F2Z-15K859-BA
I received (2) of these sensors for $25.00
Removing The Sensors:
Removing the sensor isn’t difficult. They can be accessed from the backside of the bumper.
The sensor clips in to a housing that snaps in to the bumper. If you look at your new sensor (below), you’ll be able to use it as a reference to find the clips by feel. Pull back on the clip with your finger while pushing the sensor through the bumper from the outside of the bumper. Once you get both clips over the tabs on the sensor, you’ll be able to pull it out.
When you push the sensor through the bumper, the housing it clips in to will remain.
Once the sensor is out of the bumper, you call pull it down and unplug it.
Old sensor above / New sensor below
Below are photos of the new sensor:
Other Problems:
Some people experience a problem with the rear sensor system beeping erratically when in reverse, and when nothing’s behind the vehicle. Ford has a TSB which we have HERE (TSB 05-6-4). The TSB states that the system can give false warnings due to moisture / condensation, or a dirty sensor. It can also be caused by contamination in the gap around the sensor. See the diagram below.
make sue the surface of the sensor is clean and dry. Also make sure the gap is free of debris. If necessary, it may help to take a hair dryer and dry out the moisture.