Experiencing issues with your 1996 Mercedes-Benz S320 remote locking system can be frustrating. While a seemingly minor inconvenience, remote locking is essential for security and ease of access. If you’re facing problems where your remote key fob fails to lock or unlock your doors, even though the central locking system works from the console, you might be looking at an issue beyond just a dead key fob battery. This article delves into a specific case focusing on the 96 Mercedes-Benz S320, exploring potential culprits like the AAM (All Activity Module), fuse locations, and antenna problems that could be affecting your remote locking functionality.
The Mystery of the Failing Remote Key
Imagine this scenario: your central locking button inside your Mercedes-Benz S320 works perfectly, locking and unlocking all doors. However, your remote key fob is unresponsive. You might initially suspect the remote itself – perhaps a dead battery or a faulty key. In a troubleshooting process, attempting to use a spare or even a used remote (after proper key blade and RFID chip transfer) and still encountering failure points towards a deeper issue within the car’s system itself, rather than just the remote.
Investigating Potential Causes: Beyond the Key Fob
When remote functionality fails while the console switch operates normally, it indicates the central locking actuators and much of the wiring are likely functional. The problem may lie in the signal reception or processing pathway for the remote command. In a 1996 Mercedes-Benz S320, the AAM plays a crucial role in managing various electronic functions, including the remote locking system.
One should consider potential interruptions in the radio frequency signal path. While the original case didn’t explicitly point to a fuse issue, checking the fuse box diagram for fuses related to the “central locking system”, “antenna amplifier” or “accessory control module” could be a prudent step in a general diagnostic approach. Locating these fuses and ensuring they are intact is a quick preliminary check. Similarly, while antenna location for the remote receiver in a 1996 S320 might not be immediately obvious, a break or poor connection in the antenna system could weaken signal reception. Although in the referenced case, even swapping the antenna didn’t resolve the issue, it remains a potential point of failure to consider in a broader context of remote locking problems.
Dealer Diagnosis and AAM Replacement: Pinpointing the Root Cause
In the described situation, after exhausting basic checks, a professional diagnosis using Mercedes-Benz diagnostic tools (like Star Diagnosis – SD) became necessary. Dealer technicians can use SD to communicate with the AAM and assess its functionality. Communication problems or intermittent function errors within the AAM, as revealed by the diagnostic scan, can strongly suggest an internal AAM fault.
The resolution in this particular case was the replacement of the AAM. Interestingly, the existing AAM was seemingly functional in most aspects except for the remote receiver section. The replacement process involved:
- Saving Configuration: Using SD to extract the existing option settings from the old AAM.
- Physical Replacement: Disconnecting and replacing the old AAM with a new unit. This is described as a straightforward process.
- Programming: Programming the new AAM using the saved configuration data. This essentially configures the new AAM to match the car’s specific options and features.
- Remote Synchronization: The new AAM immediately synchronized with the existing remote key fobs, restoring remote locking functionality.
Conclusion: AAM and Remote Locking Functionality
This case highlights that a fully functional 1996 Mercedes-Benz S320 in most respects can still suffer from a specific failure within the AAM that solely affects remote locking operations. While checking fuses and antenna connections are valid initial troubleshooting steps for remote locking issues, a faulty AAM should be considered, especially when console central locking works but remote operation does not. Replacing the AAM, though potentially costly (around $600 in the described case), can be the necessary solution to restore remote locking functionality in such scenarios. For owners prioritizing remote access, especially for safety and convenience, AAM replacement becomes a justifiable repair. However, if manual locking is acceptable, bypassing the remote function could be a cost-saving alternative.
