Reverse Sensing System Troubleshooting

The reverse sensing system on my 2006 F-150 stopped working recently. I had not noticed that the off light was illuminated on the switch and I while I was backing up, it dawned on me that there was no beeping from the reverse sensing system.

The reverse sensing system OFF light being illuminates is one of the key determinations for where to start troubleshooting. If the OFF light is illuminated ALL of the time, even when parked and driving forward then you most likely have a problem with the module/speaker.
If however the OFF light only illuminates when you put the vehicle in reverse then you most likely have a bad sensor or wiring to the sensors. We will tackle the sensor problem first.

To troubleshoot the sensors, park the vehicle in a quiet and safe place. Put a chock BEHIND one of the wheels. Then turn the key to the run position but DO NOT start the vehicle. Then place vehicle in reverse. Walk behind the vehicle and place your ear close to each of the sensors.
You should hear a faint, tic - tic - tic - tic. The sensors are ultrasonic and you should be able to hear each one fire. Listen to each one until you find one that is not making any sound. That is probably the bad one. This assumes that you have not been in an accident or had any damage recently, that should be rather obvious. Also take a look at the sensor wiring connector for corroded or loose connections. If you have to replace a sensor they are about $150 each from the dealer.

Now if the OFF light is illuminated all of the time then we probably have a speaker or module issue. The speakers appear to be a common problem as there was a tech bulletin issued and their is a Parking Distance Control Kit  P/N 4L1Z-15A866-AA that is specifically addressed for the Tech Bulletin. In my 2006 F150 Crew Cab, the module was located on the drivers side up under the dash, up above the drivers left foot. Lay on the floor where your left foot would go and look up. You should see a black box with a speaker on it.

I used a multimeter to take a resistance check of the speaker and received a reading of infinity. The speaker appeared to be open, a common failure mode for speakers. The resistance should be close to the impedance of the speaker, about 4 ohms for a speaker with 4 ohms of impedance.

I picked up a new speaker from the dealership for $34 even though I found it online for much cheaper. I felt ripped off but I wanted to get it fixed and not have to wait for shipping since when I put things off I almost never get back to them again soon.

I replaced the speaker and my system started working again just fine.

Now if you want, you can take the vehicle to the dealership and they can hook up the computer and they can tell you which sensor or part to replace but I do not like paying over $100 and waiting half of the day for that. The reverse sensor engine codes are not readable by most of the scanners. I have a decent scanner that can read extended codes on most makes but nothing on the reverse sensing system.