Park Assist Off Message / Unwanted Or False Park Assist Alerts / No DTCs – 2019-2021 Chevrolet Silverado & GMC Sierra

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Bulletin No.: PIT5836
Published date: 04/22/2021
Preliminary Information
PIT5836 Diagnostic Tips For Park Assist Off Message / Unwanted Or False Park Assist Alerts / No
DTCs
ModelsBrand:Chevrolet Chevrolet GMC GMCModel:

Silverado 1500 (New Model) Silverado
Sierra 1500 (New Model) Sierra

Model Years:

2019
2020 – 2021
2019
2020 – 2021

VIN:
from to
All All
All All
All All
All All

Engine:

All All All All

Transmissions:

All All All All

Involved Region or Country Additional Options (RPO)

Condition

Cause

North America
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 Off” 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 effort 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 Off 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 Off 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 flashing 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 file or grinding wheel to remove any burrs or flashing.
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 1
Modified 4/22/2021 – Created on.

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