Aero Shutter Diagnostic Tips

The aero shutters on some 2019-2021 Silverado 1500, Tahoe, Suburban, Sierra 1500, Yukon, Escalade; 2020-2021 Silverado 2500HD/3500HD and Sierra 2500HD/3500HD models may have several conditions that could potentially cause improper shutter operation. (Fig. 1) Several DTCs may be set, depending on the specific conditions. When checking aero shutter operation, be sure to look for electrical integrity issues, displaced louvers/vanes, and debris that may block movement.


Fig. 1


Here are a few tips to follow when diagnosing any aero shutter conditions on these vehicles. Refer to Bulletin #21-NA-077 for complete details on all diagnostic steps.

TIP: A shutter performance issue will always set DTC P059F (Active Grille Air Shutter 1 Performance) and U0284 (Lost Communication with Active Grille Air Shutter Actuator 1) for the upper shutters and DTC P05AE (Active Grille Air Shutter 2 Performance) and U0285 (Lost Communication with Active Grille Air Shutter Actuator 2) for the lower shutters. Shutters should never be replaced if these DTCs are not present.


Communication Concerns

Check for DTCs U0284 and U0285. On light-duty trucks, these codes may be paired with DTCs U0632 (Lost Communication with Cooling Fan Motor), U0633 (Lost Communication with Engine Cooling Fan 2), U01B0 (Lost Communication with Battery Monitor Module) or U1345 (Engine Control Module LIN Bus 1).

If any of these codes are set, check the integrity of the following components:

  • Aero shutter fuse
  • Engine wiring harness
  • Jumper harness to the shutter actuators
  • X133 connector and other connectors to the aero shutter
  • J170 splice (light-duty trucks only); even a small amount of movement of the splice may cause an intermittent communication issue (Fig. 2)


Fig. 2


Shutter Obstructions

If DTCs P059F and P05AE are set, check for any debris in the upper and lower shutters (Fig. 3), a louver/vane that is disengaged from the linkage, or a shutter that is binding. Try to remove any debris by hand or using compressed air before removing the front fascia of the vehicle or the shutter.


Fig. 3


On light-duty trucks, the upper shutter may be binding on the air induction plenum (upper driver’s side).

On SUVs as well as light-duty trucks, the upper shutter also may be binding on the horn or bracket (upper passenger’s side). There should be at least 0.40 inches (10 mm) of clearance between the shutter louver/vane and horn. (Fig. 4, #1)


Fig. 4


TIP: For 2020-2021 Silverado 2500HD/3500HD models with a fourth lower row of louvers/vanes, refer to Bulletin #21-NA-071 for the Lower Shutter Louver Modification procedure.


Shutter Test

Functionally test each shutter assembly to fully open and fully closed twice. If the shutters fully open and fully close twice without any stoppages, do not replace the shutter assembly.

TIP: On 2019-2021 Silverado 1500 and Sierra 1500 models and 2020-2021 Silverado 2500HD/3500HD and Sierra 2500HD/3500HD models equipped with upper and lower shutters, the top passenger-side louver/vane of the upper shutter is intentionally missing from the shutter assembly for airflow reasons. Do not replace the shutter for the missing louver/vane.

Refer to Bulletin #21-NA-077 for additional information.


– Thanks to David MacGillis, Kevin Minor and Hassan Abdallah


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  2. Always check the connectors to the Aero shutter for corrosion and water intrusion. If there are signs of water, but not corrosion, check the seal condition of the connectors. If they are not damaged, apply dielectric grease to the connector. If there’s corrosion present, proceed to replace the shutter. Take photos and hold the part for return. Refer to Bulletin #21-NA-077 for additional information.

  3. So recently I ran into another issue with these shutters, where plug on a lower shutter ends up being full of water and start shorting out contacts, which if memory serves well are Ground, Ground, Vsupply, Lin bus. also forming corrosion which interestingly is of a navy blue color, so this can create variety of conditions, from intermittent to constantly down Lin Bus1 as the last one I dealt with. Solutions vary, if pins and connections are ok appropriate cleaning and loading plug up with non conductive grease can be sufficient to not only fix issue for time being but avoid it in the future all together, possibly might be a solution to new vehicles to address issue at PDI and avoid upset customer with new vehicle and waste money on diagnose and repair something that could have been avoided in the first place.

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