Ok lets get started, I have a 2010 Chevrolet Avalanche and it has 4 parking assist sensors in it's rear bumper. This intractable can be used on and vehicle to the best of my knowledge ,weather you have front or Rea or both. So I went to my favorite mechanic shop and they said the error that came p on my DIC (driver information center) "service parking assist " was due to one or more of my sensors in the rear bumper. After they finished and found that there were 2 of the 4 need replacement and the wiring harness was fine. I also found out with some investigation that most of the aftermarket sensors did not work properly, but that is another issue.
So off to the dealer for the sticker shock, they were anywheres from $179.00 to $250.00.And then add the dealer install labor the price just kept getting worsens I said a search like Ebay could find them cheaper but most likely aftermarket and not compatible.
So above you will see what I found in my own search by removing sensor and inspecting them. I know it's hard to see but the sensor to the right actually has a pin rotting off. This is partially due to automotive mechanics poking around with a sharp needle type electrical tester. Most garages have them in their tool box and IN MY HUMBLE OPINION they should be tossed . They may find an issue and then make a decent repair but when your vehicle is driven and hit by all the road elements the holes poked into the wires ends up doing more damage by rotting connections and or the wires. In my case I found that each and every sensor had these poke marks which means sometime down the road I will end up replacing the complete harness.
My repair I was able to push out the pin from the socket but then found as I expected that the receiver pin socket was also rotted so now I have a sensor without a third pin but also a socket that due to what I like to call hammer mechanic was rotted as well.
When I spoke to the mechanic about this , he stated that they routinely check cable for voltage and then go to inspect device.Great , why not just unplug device and check voltage in the socket rather than poke wires and cause issues with water and elements getting in there causing further issues.
In my case I was lucky enough to find in my supply some pins and socket that would work in a pinch.The pictures above show socket pins from my supply of materials I used for making up cables.I had the crimping pliers which makes it better but you could also do it with a small pair of needle nose pliers.
So here is how I found the defective or non working sensor, easily done.I have read everything on the web as to how to test them from putting your ear against them and listing for the noise they make to using a stethoscope to hear them, neither worked for me. Ok so now here you need to use some caution , you need the vehicle in reverse to get sensors to turn on. What I did was chock all wheels ,best if done an somewhat level surface but I had none so I backed up to my garage , chocked all 4 wheels . Insert key in ignition and turn to accessories or whatever but not to start.You can unroll your windows to hear the alert from the vehicle but not really necessary. You will see in above photos I have an old iPhone and a pair of ear phones, probably could just use an external speaker but I used what I had for this. I downloaded an app free from app store called Mobil ears, actually used for hearing impaired people that need help watching tv or just listening to conversations. I plugged the ear buds in and then started the app, I went to each sensor and placed the microphone end of the phone and could actually hear the sensors making their noise. Simple , from there I was able to find the suspect sensor and make the repair myself. I save hundreds of dollars ,no dealer cost and found good OEM sensors .