Service Bulletin

Bulletin No.:

21-NA-077

Date:

May, 2021

INFORMATION
Subject:

Information on Aero Shutter Related Diagnostic Codes

Brand:

Model:

Cadillac

Escalade Models

Model Year:

Date Breakpoint:

from

to

from

to

2019

2021

SOP

June
30, 2021

2019

2019

SOP

June
30, 2021

SOP

June
30, 2021

Engine:

Transmission:

All

All

Silverado 1500
(New Model)
Silverado 1500
(New Model - 12th
VIN Digit = 7) - 4WD
Chevrolet

Silverado 1500
Silverado
2500HD/3500HD
Suburban
Tahoe
Sierra 1500
(New Model)

GMC

2020
2021
2019
2019

2019

Sierra 1500
Sierra
2500HD/3500HD

2020

Yukon Models

2019

Involved Region or Country

2021

North America, Europe, Middle East, Uzbekistan, Russia, Israel, Palestine, Chile,
Columbia, Ecuador, Paraguay, Peru, Uruguay, Japan, S. Korea, Thailand, Philippines,
Australia and New Zealand.

Additional Options (RPOs)
Condition

Some customers may comment on seeing a Check engine lamp illuminated in the DIC.

Cause

The cause of the condition may be a various combination of Aero shutter related
diagnostic codes.

Correction

Check Aero shutter operation, electrical integrity, displaced vanes, and for debris that
could potentially cause the shutter movement to be blocked, following the Service
Information below.

Copyright 2021 General Motors LLC. All Rights Reserved.

Page 2

May, 2021

Service Information
Silverado/Sierra 1500 (New Model) and Silverado/
Sierra 1500
U0284 / U0285
If these codes are paired with any of U0632 / U0633,
U01B0 and U1345, please do the following:
1. Check the fuse for the Aero shutters to ensure that
it is not loose.
2. Check the continuity on the engine wiring harness
to see if there are any high resistances present
along the wiring. If any corrosion is found, repair
the harness. (And report where the failure occurred
with photos).

Bulletin No.: 21-NA-077

6. Perform a functionality check on the shutters. If
they do work, then do not replace the assemblies,
if they were not replaced at step # 5.
7. Check the X133 connector for corrosion and water
intrusion. Additionally, check the other connectors
to the Aero shutter.
8. If there are signs of water, but not corrosion, please
check the seal condition of the connectors. If they
are not damaged, please apply dielectric grease to
the connector. If there's corrosion present, proceed
to replace the shutter. Take photos and hold the
part for return.
P059F / P05AE
Please do the following:
Note: For vehicles equipped with upper and lower
shutters, the upper shutter, top passenger side louvre/
vane is intentionally missing from the shutter assembly
for airflow reasons. DO NOT replace the shutter for this
reason.

5821156

3. Check the integrity of the J170 splice. Moving this
splice, even small amounts, can cause intermittent
communication issues. If any issues are detected
in the splice, repair the splice and report what was
repaired.
Note: If the J170 splice is found to be an issue, replace
the entire splice, do not attempt to repair it. Cut out the
splice for part return and submit a photo,taken prior to
cutting the section where the issue has been
detected.
4. Check the engagement of the jumper harness to
the shutter actuators. Ensure there is no soft
connection.
5. Check the continuity jumper harness for the Aero
shutters to see if there are any high resistances
present along the wiring. If any corrosion is found,
replace the Aero shutter, not the wiring.

5821157

1. Check for any debris in the upper and lower
shutters. If found, please remove the debris.
2. If there is no debris evident, please look for a
louvre/vane that is disengaged from the linkage. If
the vehicle has a shutter with this condition, please
engage the louvre/vane in the shutter assembly. If
shutter is operational, DO NOT replace the shutter.
3. Check to see if the upper shutter in open position is
binding on the air induction plenum. It is located on
the driver's side upper behind the upper shutter. If
this condition exists, secure the air induction
plenum to structure behind, using a 2–stage
push pin.

Bulletin No.: 21-NA-077

May, 2021

Silverado/Sierra 2500HD/3500HD
P059F- Upper Shutter
Please do the following:
Note: For MY 2020-2021 vehicles equipped with upper
and lower shutters, the upper shutter, top passenger
side louvre/vane is intentionally missing from the
shutter assembly for airflow reasons. DO NOT replace
the shutter for this reason.
1. Before removing the fascia of the vehicle, check for
any debris in upper shutter. Also, utilizing a mirror,
look behind the lower shutter to determine if there
is any debris lodged in the back side.
2. If debris is present, clear the debris from the
assembly by hand or compressed air. If
unsuccessful, remove the shutter from the vehicle
and clear debris, then reinstall the shutter.
3. If there is no debris, please look for a louvre/vane
that is disengaged from the linkage. If the vehicle
has a shutter with this condition, please engage
the louvre/vane in the shutter assembly. DO NOT
replace the shutter.
4. Functionality test the shutter. If they are functional,
DO NOT replace the assemblies.
P05AE - Lower Shutter
Please do the following:
1. Remove the lower shutter from the vehicle and
clear the debris if present from the assembly by
hand or compressed air.
2. For 2020-2021 vehicles only, remove the fourth
lowest row of louvers by completing the Lower
Shutter Louver Modification found in Bulletin
#21-NA-071. If the fourth lowest row is already
missing, move to step #3.
3. Check to see if there is any debris sitting in the
baffle area behind the lower shutter and clear
debris if present.
4. If there is no debris, please look for a louvre/vane
that is disengaged from the linkage. If the vehicle
has a shutter with this condition, please engage
the louvre/vane in the shutter assembly. DO NOT
replace the shutter.
5. Functionally test the shutters. If they are functional,
DO NOT replace the assemblies
6. If the lower shutter is ordered for replacement
and arrives with all 4 rows of louvers, complete
the Lower Shutter Louver Modification found in
Bulletin #21-NA-071.
U0284 / U0285
Please do the following:
1. Check the fuse for the Aero shutter, to ensure it is
not loose.
2. Check the engine wiring harness to see if there is
any high resistance present along the wiring to the
shutters. If any corrosion/damage is found, the
repair the harness. Report where the failure
occurred with photos or a detailed description.
3. Check the engagement of the jumper harness to
the shutter actuators. Ensure no soft connection.

Page 3

4. Check the continuity in-jumper harness for the
Aero shutters, to see if there is any high resistance
present along the wiring. If any corrosion is found,
replace the Aero shutter, not the wiring.
5. Perform a functionality check on the shutters. If
they do work, then DO NOT replace the
assemblies, if they were not replaced at step # 4
6. Check the X133 connector for corrosion and water
intrusion. Additionally, check the other connectors
to the Aero shutter.
7. If there are signs of water, but not corrosion, please
check the seal condition of the connectors. If they
are not damaged, please apply dielectric grease to
the connector. If there's corrosion present, proceed
to replace the shutter.
SUV’s
U0284 / U0285
Please do the following:
1. Check the fuse for the Aero shutters to ensure that
it is not loose.
2. Check the continuity on the engine wiring harness
to see if there are any high resistances present
along the wiring. If any corrosion is found, repair
the harness. (And report where the failure occurred
with photos).
3. Check the engagement of the jumper harness to
the shutter actuators. Ensure there is no soft
connection.
4. Check the continuity jumper harness for the Aero
shutters to see if there are any high resistances
present along the wiring. If any corrosion found,
replace the Aero shutter not the wiring.
5. Perform a functionality check on the shutters if they
do work, then do not replace the assemblies, if
they were not replaced at step # 4
6. Check the X133 connector for corrosion and water
intrusion. Additionally, check the other connectors
to the Aero shutter.
7. If there are signs of water, but not corrosion, please
check the seal condition of the connectors. If they
are not damaged, please apply dielectric grease to
the connector. If there's corrosion present, proceed
to replace the shutter.
P059F / P05AE
Please do the following:
Note: For vehicles equipped with upper and lower
shutters, the upper shutter, top passenger side louvre/
vane is intentionally missing from the shutter assembly
for airflow reasons. DO NOT replace the shutter for this
reason.
1. Check for any debris in the upper and lower
shutters. If found, please remove the debris.
2. If there is no debris, please look for a louvre/vane
that is disengaged from the linkage. If the vehicle
has a shutter with this condition, please engage
the louvre/vane in the shutter assembly. DO NOT
replace the shutter.

Page 4

May, 2021

Bulletin No.: 21-NA-077

3. Check to see if the upper shutter is binding on the
HORN BRACKET. It is located on the passenger’s
side upper, behind the upper shutter.
4. Functionally test the shutters, if they work do not
replace the assemblies.

Parts Information
Use the VIN and refer to the GM Electronic Parts
Catalog (EPC) to determine the proper part to order.

Warranty Information
For vehicles repaired under the Bumper-to-Bumper
coverage (Canada Base Warranty coverage), use the
following labor operation. Reference the Applicable
Warranties section of Investigate Vehicle History (IVH)
for coverage information.
For vehicles repaired under warranty, use the
appropriate labor operation for the repair performed.
Labor Operation

Description

Labor Time

1481528*

Check Aero Shutter Operation and Function

0.8 hr

Add

Complete Lower Shutter Louver Modification

0.2 hr

*This is a unique Labor Operation for Bulletin use only.

Version

3

Modified

Released March 26, 2021
Revised April 21, 2021 – Updated with Additional Models and Model Years.
Revised April 30, 2021 – Added Graphic and Detail to J170 Splice Reference.

GM bulletins are intended for use by professional technicians, NOT a "do-it-yourselfer". They are written to inform these
technicians of conditions that may occur on some vehicles, or to provide information that could assist in the proper
service of a vehicle. Properly trained technicians have the equipment, tools, safety instructions, and know-how to do a
job properly and safely. If a condition is described, DO NOT assume that the bulletin applies to your vehicle, or that your
vehicle will have that condition. See your GM dealer for information on whether your vehicle may benefit from the
information.

WE SUPPORT VOLUNTARY
TECHNICIAN
CERTIFICATION