# 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: 11031867
- Published by NHTSA: 2026\-05\-01
- Manufacturer's number: LI77.21\-P\-080503
- Manufacturer's date: 2026\-04\-30
- NHTSA component: ELECTRICAL SYSTEM

## 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. 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 \(PSD – A98 / TSSR254\).

## The document

- [NHTSA's copy of the document (PDF)](https://static.nhtsa.gov/odi/tsbs/2026/MC-11031867-0001.pdf)
- [If that address does not open, try this one](https://static.nhtsa.gov/odi/tsbs/2026/MC-11031867-9999.pdf)

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

## Components

Electrical system

## Trouble codes named

B1849, B1E75

## 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
- 2020 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/11031867](/v1/bulletins/11031867)

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