BMW X5 2008 parking sensors

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BMW X5 2008 parking sensors

Postby RYM6746 » Tue Mar 14, 2017 11:03 pm

HI, I have a X5 in at the moment that will randomly keep beeping at you when reverse is selected. It is warning you that you are about to hit an object. When bringing scan data up it is showing that both centre front sensors are intermittently picking up an object that is very close even though there is nothing in front and the car isn't moving. So I break out the pico and scope the powers and grounds all ok. Then I move on to the signal wires there is a random square waveform that changes in frequency but the amplitude of the signal is good (Compared to a sensor that isn't reporting an object). A sensor that isn't reporting an object also has a random square waveform that changes in frequency. I have tried to use a frequency maths channel to compare the suspect sensors against the known good but I couldn't gain much diagnostic value out of comparing the two. Does anybody know if and how I can use/setup the scope to compare the two sensors with a good diagnostic value to the waveforms? I am relatively new to this kind of sensor and I can see good voltages everywhere but I am unable to pick out the hidden information that is within the signal which appears to be a randomly changing square waveform.
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Re: BMW X5 2008 parking sensors

Postby STC » Tue Mar 14, 2017 11:48 pm

Hi Rym.

Live Data / Actual Values would be your best friend here. They will normally read between 0 - 255cm (0 - FF in Hexadecimal)

Then you have the option of swapping them around to narrow down / corner the suspect.
that both centre front sensors are intermittently picking up an object that is very close even though there is nothing in front and the car isn't moving


Water Ingress ?? Wrong Paint? .... .... ... ....

I am unable to pick out the hidden information that is within the signal which appears to be a randomly changing square waveform.


Linbus ??? Time taken deciphering it would outweigh the cost of one new sensor. Which could be used again and again as a "Known Good"
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Re: BMW X5 2008 parking sensors

Postby RYM6746 » Wed Mar 15, 2017 9:18 pm

I popped out the terminals at the ecu multiplug and swapped the suspect bad for a known good and the fault jumped. So I ordered 1 sensor as they were £90 a pop and plugged it in to the suspect sensor. And it fixed the whole problem. Turns out even though you only disrupt the signal of one sensor the scan tool would spit out the information that there is something in the proximity of both sensors. To prove this after I had fixed the problem I put a metal bin right in the very corner of the bumper almost down the side of the front wing and the scan tool reported something on both the centre right and corner right. It may well of just about picked it up on the centre sensor but I fixed the car with only 1 sensor further backing up my theory. Maybe it's just written in the software that way. Or maybe not but I definitely had more evidence suggesting it is.
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Re: BMW X5 2008 parking sensors

Postby STC » Thu Mar 16, 2017 1:39 am

Fixing these types of fault are a challenge but a result can be achieved with some effort. However, Having to Second guess the design and fault strategy is another story !!!

Quite cruel really in a civilised society.

Well done on your fix, Thank You for taking the time share that with us :D :D :D
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