PIT5836

Bulletin No.: PIT5836
Published date: 03/31/2022
Preliminary Information
PIT5836 Diagnostic Tips For Park Assist O Message / Unwanted
Or False Park Assist Alerts / No DTCs
Models
Brand:
Model:
Model Years:
VIN:
from
to
Engine:
Transmissions:
Chevrolet
Silverado 1500 (New Model)
2019
All
All
All
All
Chevrolet
Silverado
2020 - 2021
All
All
All
All
GMC
Sierra 1500 (New Model)
2019
All
All
All
All
GMC
Sierra
2020 - 2021
All
All
All
All
Involved Region or Country North America
Additional Options (RPO)
Condition
Cause
UD7 or UD5
Some customers may comment on unwanted/false park assist alerts suggesting
there is an object in front and/or behind the vehicle when there is nothing there.
This condition can lead to the system disabling itself and a "Park Assist O "
message will be displayed in the DIC. Also, the LED in the park assist switch will be
disabled.
If an issue exists with the way the park assist sensor and/or bezel is mounted or
painted, the sensor can ground out or get squeezed and pick up normal vehicle
vibrations. These normal vehicle vibrations would not ordinarily be picked up by the
sensor when properly mounted and isolated from the vehicle. These vibrations can
be interpreted by the park assist sensor as an object, when in fact there is no object
present. Because the sensor is working normally, there will be no DTCs set. The
cause of this condition could be one of several items and this document will provide
some diagnostics tips.
Correction:
- Using GDS2, go into Module Diagnostic/Park Assist Module/Data Display/Parking Assist Disable History 1-4 and
5-7 Data and view the disable history. If the disable history shows "Trailer or Other Object Attached" this is a good
indication there could be an issue with a park assist sensor(s) grounding out or getting squeezed. Don't over look
the obvious things such as a trailer hitch installed or anything else attached to the vehicle.
Note: Be careful if the disable history shows "Manual Disable" along with "Trailer or Other Object Attached".
Many times in an e ort to make the Park Assist system operational, a customer will try cycling the park assist
manual disable switch. This can cause "Manual Disable" to be displayed in the disable history and may mislead
your diagnostics.
- Question the driver to see if they have received any unwanted/false park assist alerts. If so, the Parking Assist
Display, located in the DIC, will indicate where the false alert is being displayed/detected. Use this information to
help narrow down which sensor(s) should be inspected. Example: the Parking Assist Display is falsely indicating an
object at the left front of the vehicle. With this information the left front park assist sensors/bezels should
be inspected more closely.
- If there are no unwanted/false parking assist alerts and they only have an issue with the Park Assist O
message, then on trucks with front and rear parking assist, try the following to help determine if the issue is with
the front or rear sensor(s)/bezel(s). Connect GDS2 and go into Module Diagnostic/Park Assist Module/Data
Display/Parking Assist System Data and monitor the following two parameters: "Attached Object Detected Front"
and "Attached Object Detected Rear". See which parameter goes "active" when the Park Assist O message is
displayed and use this to determine if the issue is with the front or rear sensor(s)/bezel(s). This step can be
omitted on vehicles with only rear park assist, as it would be only the rear sensor(s)/bezel(s) to inspect.
Note: On vehicles with both front and rear parking assist systems, it cannot be determined if there is an issue
with either the front or rear parking assist sensor(s) or bezel(s) by the transmission position (Drive or Reverse)
alone. Example: When the vehicle is shifted into reverse, both the front and rear parking assist sensors are active.
Also, while driving forward the system determines if anything is attached to either the front or rear of the vehicle.
Once you have determined which sensor(s) to inspect, look for the following issues:
1. Perform a visual inspection of the park assist sensor(s) and bezel(s). Look for any stone chips/dents, paint
chips, damage, etc., as well as, any issues with the silicone ring. See example (1) below of a silicone ring which is
not properly installed. If any issues are found then repair as necessary.
Note: In most cases, these next inspections will require the bumper to be removed.
2. Inspect the park assist sensor bezel(s) for not being properly mounted in the bumper hole. If the bezel in not
properly mounted into the bumper hole it can lead to a sensor grounding out or the sensor getting squeezed.
The bezel has four locking tabs that secure the bezel to the bumper. Make sure all four mounting tabs are fully
engaged. See example (2) for a mounting tab that is not fully engaged (view from the back side of the
bumper/bezel). If any tab is not fully engaged it can protrude into the opening where the park assist sensor
mounts and cause it to ground out or get squeezed. See example (3) for a tab not fully engaged and protruding
into the opening for the sensor. If any of the bezel mounting tabs are not fully engaging, inspect the following:
- Burrs on the back side of the bumper hole, see example 5 and 6
- Excessive paint/clear coat on the bumper around the mounting hole , see example 7.
- Plastic ashing on the park assist sensor bezel itself, see examples 8 and 9.
- Inspect the bumper hole for being slightly too small. The bezel should easily slide into the bumper hole without
force.
If any of these concerns exist, then use a le or grinding wheel to remove any burrs or ashing. If needed,
enlarge the bumper hole opening. On any exposed/bare metal apply an Anti-Corrosion Treatment, see
Document ID: 2096919. After repairing any bumper hole or bezel issues then reinstall the bezel and make sure
the four mounting tabs are fully enaged and then reinstall the park assist sensor. There is no need to replace the
bezel or sensor unless they are damaged.
3. If the park assist sensors have been painted, it is important that only the tip of the sensor is painted and clear
coated. The tip of the park assist sensor is isolated from the rest of the sensor body by an internal decoupling
ring. If paint or clear coat is allowed to run or drip down the sides of the sensor's tip and/or into the gap between
the body and sensor tip, as shown below, this can cause the sensor to ground out.
Warranty Information
For vehicles repaired under the Bumper-to-Bumper coverage (Canada Base Warranty coverage), use the
appropriate labor operation for your repair. Reference the Applicable Warranties section of Investigate Vehicle
History (IVH) for coverage information.
Version History
Version
Modi ed
1
4/22/2021 - Created on.
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