# Service bulletin LI77.21\-P\-080503

A bulletin is a manufacturer's communication to its dealers, as NHTSA indexes it. The summary is NHTSA's. The document is the manufacturer's: read it at NHTSA. A bulletin is not a recall, and listing a model year does not mean every vehicle of it is concerned.

- Type: Service bulletin
- NHTSA id: 11031554
- Published by NHTSA: 2026\-04\-25
- Manufacturer's number: LI77.21\-P\-080503
- Manufacturer's date: 2026\-04\-24
- NHTSA component: VISIBILITY/WIPER

## NHTSA's 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 \(PSD – A98 / TSSR254\).

## The document

- [NHTSA's copy of the document (PDF)](https://static.nhtsa.gov/odi/tsbs/2026/MC-11031554-0001.pdf)
- [If that address does not open, try this one](https://static.nhtsa.gov/odi/tsbs/2026/MC-11031554-9999.pdf)

The document is the manufacturer's. This site does not hold it.

## Components

Glass, wipers and mirrors, Wipers and washers

## Vehicles listed

- 2024 MERCEDES\-BENZ AMG GLC43
- 2024 to 2026 MERCEDES\-BENZ AMG GLC43 4MATIC
- 2024 to 2025 MERCEDES\-BENZ AMG GLC43 4MATIC COUPE
- 2024 to 2025 MERCEDES\-BENZ AMG GLC63 S E
- 2025 to 2026 MERCEDES\-BENZ AMG GLC63 S E 4MATIC\+
- 2025 to 2026 MERCEDES\-BENZ AMG GLC63 S E 4MATIC\+ COUPE
- 2023 to 2026 MERCEDES\-BENZ GLC 300
- 2023 to 2026 MERCEDES\-BENZ GLC 300 4MATIC
- 2024 to 2026 MERCEDES\-BENZ GLC 300 4MATIC COUPE
- 2024 MERCEDES\-BENZ GLC 300 COUPE
- 2025 to 2026 MERCEDES\-BENZ GLC 350 E 4MATIC
- 2026 MERCEDES\-BENZ GLC43 4MATIC COUPE

JSON: [/v1/bulletins/11031554](/v1/bulletins/11031554)

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