Park assist sensors-FIXED!

[OR VietVet]

A friend of mine at the American Legion has a 2011 Tahoe LT and he says he gets an error message for his park assist sensors and then he just turns it/them off and uses his back up camera. I saw 3 nickel sized round spots across the back lift gate at the bottom. Are those the sensors he is speaking of and what is the typical problem? All bad or one? Are they the sensor(s) I am looking for? Located elsewhere? Thanks in advance.

Is it or are the 4 spots part of the backup camera system? Please help with part numbers too.

 

[gooffeyguy]

Parking sensors are the nickle sized round spots along the top of the rear bumper cover. They're not on the liftgate

You can see the two left ones in the pic just under the chrome strip

 

[OR VietVet]

Sorry, I did view them but forgot by the time I got home, the location on the rig. Thanks for the clarification and there were 4 of them. So, knowing that, have you or anyone seen or had problems with them and was it narrowed down to one sensor being bad, all 4 causing problems like I described or something else. He did say that when he turns that system off and shuts down the vehicle, the next time he starts the vehicle, they are default activated again.

 

[Doubeleive]

Sorry, I did view them but forgot by the time I got home, the location on the rig. Thanks for the clarification and there were 4 of them. So, knowing that, have you or anyone seen or had problems with them and was it narrowed down to one sensor being bad, all 4 causing problems like I described or something else. He did say that when he turns that system off and shuts down the vehicle, the next time he starts the vehicle, they are default activated again.

you can test them individually, just get a person that doesn't want to kill you for a helper, be parked somewhere with nothing behind you for at least 10-15 feet, put the key on run or start it up and then put it in reverse, then go to the back and wave your hand over each sensor one at a time so you will have to stand directly to the side and wave over the 2 you can reach and then go to the other side and wave over those 2 (make sure you are not covering one while waving over another one or you will get a false reading, which ever one does not make a tone/beep happen is your culprit. it could be other things but that is a place to start (basic functionality test) it might only fail when the message comes up not sure on that. I don't know if the error message makes them all shut down or if they still work with just the defect as I have never had a problem with mine. there is a module for the system also but testing that i am sure takes the tech2, if you have a tech2 and scan the system you might find a historical code for the backup sensor system which theoretically would point to the problem. i.e. sensor #2 fault, etc
you can visually check the sensors also if one has a dent or ding in the center or is not seated properly or is even very dirty that would create a problem as well

 

[OR VietVet]

When you say, "wave over the two on each side" are you treating the pair of two, on each side" as a unit of two or can I wave over each one individually at each side? This gut has lots of money so, I am betting that he will say just replace the complete set of 4 of them.

Plus, sorry for the confusion I might have caused by saying, "mounted in the lift gate". I should have remembered that when I was looking at them, I reached in behind the bumper to feel for access. Is the access restricted and have to disassemble covers for access or are they easily accessible? I did not get down on ground to look in there, YET.

 

[OR VietVet]

I just watched a couple you tube videos and they set in reverse with KOEO and used the recorder on their cell phones and there was a constant pulse noise on the good sensors when the microphone was held right up to the sensor face and no pulse on the bad one(s).

 

[Joseph Garcia]

If you have access to a Tech 2, it will tell you specifically which sensor is the issue. I went through this last year, and the Tech 2 made troubleshooting a piece of cake.

 

[Doubeleive]

When you say, "wave over the two on each side" are you treating the pair of two, on each side" as a unit of two or can I wave over each one individually at each side? This gut has lots of money so, I am betting that he will say just replace the complete set of 4 of them.

Plus, sorry for the confusion I might have caused by saying, "mounted in the lift gate". I should have remembered that when I was looking at them, I reached in behind the bumper to feel for access. Is the access restricted and have to disassemble covers for access or are they easily accessible? I did not get down on ground to look in there, YET.

there are 4 sensors so test 1 at a time. unless you are stretch armstrong you will only be able to reach 2 from each side
the phone mic trick really does not work well at least it did not with my phone

 

[Joseph Garcia]

there are 4 sensors so test 1 at a time. unless you are stretch armstrong you will only be able to reach 2 from each side
the phone mic trick really does not work well at least it did not with my phone

Very true. Luckily, my bad sensor was an outside one.

 

[OR VietVet]

Yea, the you tube showed the outer sensors as easy to get to but the inner two required some covers removal to access.

 

[OR VietVet]

Since I have done some more research about hearing the pulses from the sensors, could you theoretically use a "mechanic's stethoscope" to hear those pulses?

 

[OR VietVet]

Well, the customer/friend just left and I had the failed/bad left outer sensor diagnosed in 30 seconds. He turned key on and put it in reverse and I listened to all four and the three that still worked had a distinct Geiger Counter noise and the bad one was dead silent. I was gonna use an app that reads decibel levels, that I saw a few times on you tube, but I just used my mechanic's stethoscope and used the nose cone adaptor and held it over the sensor and the noise was there. Very easy to detect.

 

[Tonyv__]

Well, the customer/friend just left and I had the failed/bad left outer sensor diagnosed in 30 seconds. He turned key on and put it in reverse and I listened to all four and the three that still worked had a distinct Geiger Counter noise and the bad one was dead silent. I was gonna use an app that reads decibel levels, that I saw a few times on you tube, but I just used my mechanic's stethoscope and used the nose cone adaptor and held it over the sensor and the noise was there. Very easy to detect.

View attachment 392408

Interesting info. Thanks for sharing. Follow up to let us know if replacing that sensor fixes the issue.

I dread something like this failing on my 2015. Kind of like why you love your 05. Simple, reliable , and minimal electronics to diagnose.

 

[OR VietVet]

Interesting info. Thanks for sharing. Follow up to let us know if replacing that sensor fixes the issue.

I dread something like this failing on my 2015. Kind of like why you love your 05. Simple, reliable , and minimal electronics to diagnose.

All info I looked up said the outer two sensors were easy to pop out and in. It has a 3 wire plug in. 12 volt power, ground and signal to control unit. Easy peasy.

!I had no faith in the decibel reading app thru the microphone on my phone. I just thought of the mechanic's stethoscope idea today. Worked like a champ!

The customer/friend is hard of hearing but his girlfriend has no hearing problems. She put on the stethoscope and I walked her down the line of all 4 sensors and she was amazed that she heard the pulse noise from the three that were good and dead silence from the bad sensor. He did not want to pay the $163 fee for the GM one at RA so I had a choice of either Dorman, Standard or Bosch. I opted for the Bosch. $24.79, -$1.24 5% discount code, $4.99 shipping and total was $28.54. He was happy with that for sure. With my labor fee at $60 an hour, he should be out the door for less than $90.

 

[AirJordan613]

If you have access to a Tech 2, it will tell you specifically which sensor is the issue. I went through this last year, and the Tech 2 made troubleshooting a piece of cake.

How do you test them individually with the tech 2?

 

[OR VietVet]

Sorry, forgot to update this problem fix. Part came in and customer showed for work. Looked under there and there was a cross piece of metal at end of frame horns that covered all 4 sensors. My easy peasy access was no longer that way. Looked at you tube. Couple of screws in wheel well and a push pin and 4 screws across the top of the rear bumper cover and 2 more push pins and two 10mm bolts under the bottom edge and then a quick sideways pull at the left side of bumper cover corner and the cover pulled away. A quick unplug at the sensor, two clips holding sensor in place and reverse removal procedure and it was all working as supposed to be and his warning light was out and I could hear the pulse noise at the new sensor. $28.54 for the sensor and $40 labor and he was happy. I hope I get to replace every sensor on the NNBS Tahoe's and Yukon's in the area because the procedure for diagnosis and install is real easy.

In this instance, using a Tech 2 would have found the failed sensor, my method was way quicker. Less than 1 minute and failed sensor was found. Takes longer than that just to get the Tech 2 out and hooked up.