GM Releases Fix For GMC Sierra HD Power-Retractable Assist Step Issue

GM has released a new service update for the GMC Sierra HD related to an issue wherein power-retractable assist steps can reverse while deploying or stowing.

The problem: certain units of the GMC Sierra HD may exhibit a condition wherein power-retractable assist steps can suddenly reverse. This condition will occur when the steps are deploying or stowing.

The hazards: the power-retractable assist steps may function incorrectly when deploying or stowing. As a result the steps may stow themselves again partway through deploying, or deploy again partway through stowing.

The fix: to address the issue, GM has instructed dealerships to reprogram the K4 Assist Step Control Module for the power-retractable assist steps. No parts are needed for this service repair. Service is typically completed in approximately 30 minutes.

Affected components: Black power-retractable assist steps with LED lighting (RPO code B3L) or power-retractable assist steps with LED perimeter lighting and bright accent (RPO code BRS).

Affected vehicles: 

• 2021 GMC Sierra HD 2500
• 2022 GMC Sierra HD 2500
• 2023 GMC Sierra HD 2500
• 2021 GMC Sierra HD 3500
• 2022 GMC Sierra HD 3500
• 2023 GMC Sierra HD 3500

Number of affected vehicles: GM has not provided an estimated number of affected vehicles.

Owners should: owners can contact GMC directly with any concerns they may have using the contact information listed below.

Contacts:

• GM Service Update number: N222376580
• GMC U.S. Customer Service: 1-800-462-8782

To note, this service update also applies to certain Chevy Silverado HD trucks which have the same issue with incorrectly functioning power-retractable assist steps. The GM Service Update number and the recommended repair is the same for both makes of vehicle.

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