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April 30, 2026 Service bulletin

The panoramic sliding sunroof operates in a stepped movement

Mercedes-Benz technical service bulletin LI77.21-P-080503 for 2020-2026 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
Electrical system
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. In combination with one, serval, or all of the following Fault Codes stored in the panoramic roof control unit (PSD, A98, TSSR254): • B184954 • B184955 • B1E7554 • B1E7555 Note: Please see LI77.21-P-075807 for complaints of the sliding sunroof panel of panoramic sliding sunroof reverses (temporarily, once, multiple times) during closing process without an entrapment event 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 95 complaints in the electrical category.

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