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April 24, 2026 Service bulletin

Complaint The panoramic sliding sunroof operates in a stepped movement

Mercedes-Benz technical service bulletin LI77.21-P-080503 for 2023-2026 Mercedes-Benz GLC 300, 2024 Mercedes-Benz AMG Glc43 and 2023-2026 Mercedes-Benz GLC 300 4matic and others.

Bulletin number
LI77.21-P-080503
Component
Visibility/wiper
Summary
Complaint The panoramic sliding sunroof operates in a stepped movement. The panoramic roof becomes denormalized without an apparent reason (not directly after control unit replacement). Automatic operation of the glass panel and roller sunblind is not possible; only tip‑mode operation is available. Cause Resetting the panoramic roof control unit (PSD – A98 / TSSR254) can lead to loss of normalization. The root cause for the control unit reset is currently under investigation. Remedy Contribution to cause analysis: • Print the attached document “Panoramic Roof Customer Questionnaire.” • Complete the questionnaire together with the customer. • Open a TIPS case and attach the completed questionnaire. • Submit the TIPS case to the Body / Chassis / Entertainment inbox. Repair: Perform Initial Start‑Up of the panoramic roof control unit (PSD – A98 / TSSR254).

Owners of these vehicles have filed 6 complaints in the visibility category.

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