2021 Mercedes-Benz AMG GT P Button Malfunction TSB

Symptoms of the Mercedes-Benz AMG GT P Button Malfunction

Owners of 2021 Mercedes-Benz AMG GT vehicles may experience a specific issue with the Direct Selection Interface (DSI) selection lever module. The primary symptom is that the vehicle "DSI selection lever module cannot be switched to park position "P"" and a general "malfunction of "P" button" is observed. This means the gear "cannot be engaged" into park.

This issue directly impacts the ability to securely park the vehicle. It's important to address this Mercedes-Benz AMG GT P button malfunction promptly to ensure proper vehicle operation and safety.

Important Warnings for Owners

If you encounter this issue, Mercedes-Benz advises that the "Vehicle can still be placed into park by opening driver's door, or turning off ignition." For detailed instructions on how to manually engage park, owners should "refer to operator's manual section, "Engaging park position P," for additional instructions." This information is critical for safely securing your vehicle until a repair can be performed.

Fault Codes / DTCs

When the 'P' button malfunction occurs, diagnostic trouble codes (DTCs) related to the N150 - DIRECT SELECT interface (DSI) (DSI290) control unit may be stored. These codes help technicians pinpoint the exact nature of the problem.

Code	Description	Module
P085015	"The button 'Gear range P' has a malfunction. There is a short circuit to positive or an open circuit."	N150 - DIRECT SELECT interface (DSI) (DSI290)
P085011	"The button 'Gear range P' has a malfunction. There is a short circuit to ground."	N150 - DIRECT SELECT interface (DSI) (DSI290)

These DTCs indicate an electrical fault within the 'P' button circuit, either a short to positive, an open circuit, or a short to ground.

Diagnosis and Trigger Conditions

The root causes for the Mercedes-Benz AMG GT P button malfunction are typically environmental factors affecting the DSI module's internal components. The TSB identifies two primary causes:

• Contamination/ingress of dust: Fine particles can interfere with the electrical contacts or mechanical operation of the 'P' button.
• Short circuit due to ingress of water: Moisture, even in small amounts, can cause electrical shorts on the printed circuit board, leading to the malfunction.

Technicians will inspect the DSI module for evidence of these conditions to confirm the diagnosis.

Repair Procedure Summary

The repair for the Mercedes-Benz AMG GT P button malfunction focuses on cleaning the affected components. The general procedure, as outlined in TSB LI27.60-P-077704 (Version 3, dated 6/7/24), involves:

1. Removal of the DSI: The Direct Selection Interface (DSI) module, referenced as AR27.60-P-0901FRX, is carefully removed from the vehicle.
2. Disassembly: The housing of the DSI and the cover around the 'P' button are removed to expose the underlying printed circuit board (as shown in pictures 1 and 2 of the original document).
3. Inspection: The printed circuit board and the 'P' button itself are thoroughly checked for any signs of liquid residues, water, or other contamination (referencing pictures 3 and 4 of the original document for visual guidance).
4. Cleaning: The contaminated areas are meticulously cleaned using a suitable contact cleaner. This step is crucial for restoring proper electrical conductivity and mechanical function.
5. Reassembly and Testing: After cleaning, the DSI module is reassembled and then reinstalled in the vehicle. Its functionality is checked to ensure the 'P' button operates correctly and the vehicle can be switched to park.
6. Further Diagnostics: If the fault code persists after the cleaning and reassembly, technicians are instructed to follow the available guided test remedy within the diagnostic system for further troubleshooting.

Required Tools or Parts

The primary item required for this repair is a suitable contact cleaner to effectively remove dust, liquid residues, and other contaminants from the printed circuit board and the 'P' button's internal mechanisms. No specific part numbers for replacement components are listed, as the remedy focuses on cleaning existing parts.

Owner Action

If your 2021 Mercedes-Benz AMG GT is experiencing a "P" button malfunction or displaying related warning messages, it is recommended to contact an authorized Mercedes-Benz service center. Explain the symptoms you are observing, and mention the TSB number LI27.60-P-077704, as it directly addresses this issue. The repair involves specialized diagnostic and cleaning procedures best performed by trained technicians.

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NHTSA ID: 11003209