Frost to failure: Possible ultrasonic-proximity sensor issues | Tire Business

It's winter ... again ... and time for the all-too-common issue of advanced driver assistance systems (ADAS) proximity-sensor problems, compliments of the seasonal elements.

That brings us to this edition's Q&A session. Here's one from Joey W. of Rossville, Ga., who asks: "Is there an easy way to diagnose ultrasonic sensor issues?"

Good question. But unlike the sensors found on vehicles in previous decades, today's basic-parking system's distance sensors are going to be:

1) OE model specific.

2) Position specific.

These quarter-sized ultrasonic devices located in the front and/or rear bumper skin(s) are an integral part of the vehicle's ADAS system. The sensors work together in combination with cameras, RADAR — and other safety-centric modules — on basic models.

Those vehicles with more advanced ADAS called "active assist" incorporate steering, braking, transmission selection, wheel speed and ABS/ESP, as the vehicle can park and depart autonomously from a space via the ping of the vehicle owner's phone app — all V2V-V2x (vehicle to vehicle or vehicle to everything) coding.

And speaking of code, most applications will provide a fault code if the ultrasonic sensor has detected an abnormality along with ADAS-based service lights illuminated on the instrument panel (IP). This disables driver assist functionality for the car or light truck like any other related component.

Then, there is verification of ADAS sensors communication; U-code. CAN-bus and Ethernet (MOST: media-oriented system transport).

First, we need to verify a couple of items that can affect the coded message:

• Know what you are working on: Check out the specifics on the YMM you are working on, as no two cars or light trucks, including back-to-back assembly line construction, are alike.

• Visual inspection: Has the sensor been damaged due to a minor accident or brush with a parking lot bumper stop? Is there corrosion on the pigtail connectors? How about the integrity of the outward face of the ultrasonic sensor?

• Check for relevant TSBs: I know of a tech who spent two workdays on an issue for which the fix was documented in a TSB, a return to dealership for fee-free update. Therefore, you need to verify that there are no associated bulletins to the component (or associated components) that may affect functionality.

And before moving forward with your diagnostic decision, verify proper voltage and ground sources — including primary voltage source (12VDC battery). Voltage drops — discovering resistance in the electrical circuit — is the principle testing method. Without the engineered power supply, you can be chasing tail and wasting shop time.

Beyond continuous sensor exposure to the elements and aging, another elemental issue occurs during the snow season: proximately sensor connectivity problems.

And we are not just talking about the buttons in the bumper. There are other proximity devices – magnetic door sensors, photoelectric light/sun load sensors, infrared object proximity devices, to name a few, that are overall ADAS functionality dependent.

Keep in mind, it is normal to have a "dead period" between ultrasonic sensor pulses (emit/receive) observed — not for distance recognition testing — with the aid of a thermal imager as each ultrasonic sensor is OE specific regarding echo ranging.

There's a lot of moving parts for such a simple sensor, Joey. The best advice — after you've verified the customer's complaint — is to know what you are working on (YMM-trim level), authenticate a solid electrical base and like all diagnostic steps begin at the end.

I recommend reverse engineering and starting your testing with the "problem child" located in the car or light truck and moving "backwards" to the primary source of power-communication.

Lesson learned.

Pam Oakes has been embedded within the automotive industry for more than 30 years as an automotive applications engineer, instructor/course developer (for several international companies), 609 instructor/test proctor, automotive business expert/strategist, 20-year original start-up shop owner/multiple auto business owner, ASE Master automotive, Collision & Medium/HD truck technician-trainer, Diesel Class 8 instructor, automotive author, syndicated radio host and automotive-consumer news media commentator. She sits on the National Science Foundation's National Council of Autonomous Technologies (NCAT) advisory board and SAE-International Active Safety ADAS Sensor Calibration Task Force committee member and MACS board of directors.

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