3 Reasons Why Range Rover SOS System Limited Functionality

Whenever you see an SOS System Limited Functionality on your Range Rover dashboard, it signifies an issue with the system,  usually traced to a faulty Telematic Control Unit (TCU).

In some cases, the issue could result from a drained battery which renders the TCU and the SOS system inactive. With a depleted battery, the TCU can no longer contact the operating authorities whenever the SOS button is pushed. 

All of the highlighted issues will be discussed further in this article. We will also look at other causes and recommend remedies to fix the error message.

What is Range Rover SOS System Limited Functionality?

If the SOS System Limited Functionality comes up in your Range Rover, a  fault has been detected with the SOS emergency call system. The warning message is traced to a faulty or drained Telematic Control Unit (TCU) battery.  

If you are unfamiliar with the SOS emergency call system, it is designed to allow the driver to reach emergency operators in case of an emergency. The location of the driver will be automatically sent to the operating authorities. 

Once the driver presses the button, an emergency operator will be contacted. If the button is pressed by mistake, the driver can advise the agent that there is no emergency. However, if there is no response, the operator will dispatch emergency personnel to the vehicle location. 

The SOS system is activated through a button that could be located on the steering wheel or top of the windscreen, depending on your Range Rover model. 

Other factors could cause the warning message SOS system to be limited. One factor could be a wiring issue: a disconnected or damaged wire between the TCU and the vehicle’s computer system. 

When the TCU is damaged in any form, or there is a disconnection, the SOS system will not function properly. The driver must be notified of something wrong with the SOS system due to a nonfunctioning TCU. The warning could be the “ SOS system limited Functionality” warning message. 

Causes of Range Rover SOS System Limited Functionality

1. Drained TCU battery 

A drained TCU battery is one of the most common causes of a Range Rover SOS system limited Functionality warning message. The SOS system will also be nonfunctional when the TCU battery stops working. It is because TCU is important when it comes to eCall.

The SOS button is linked to the eCall system, meaning the emergency agency should be contacted once the button is pushed. With the TCU battery dead, this will not happen. 

Furthermore, the vehicle’s computer system will pick up the issue with the SOS system and then notify the driver. The notification could be the “SOS system limited Functionality” warning message. 

2. Damaged TCU

A more serious issue is a damaged TCU system; the TCU battery is easier to replace and cheaper, but the TCU itself does not. 

The TCU is responsible for controlling wireless tracking, diagnostics, and communications. Once the TCU is damaged, changing the battery will not solve the issue. Here, the TCU needs to be replaced. 

You can find the TCU in the trunk on the left side of the vehicle. It could be difficult to recognize and spot damage on the TCU. You might need a diagnostic tool to check the module before locating and replacing it. 

3. Wiring issue

The wiring of the TCU plays a major role in powering the TCU and sending information from one component to the other. For instance, when the SOS button is pushed, the wire transmits a signal to the system, calling the operating authority. 

When there is a disconnection, no call will be placed to an operating authority when the SOS button is pushed. 

Also, you need to understand that the vehicle’s battery powers components of the SOS system. With the help of wires, electric current flows to the necessary parts to keep the system going. 

If the wire is damaged, current flow to the components will be hindered, and important parts of the SOS system will remain dormant. 

Once there is any wiring problem in the system that affects the functioning of the SOS system. 

How to Fix a Range Rover SOS System Limited Functionality 

The major cause of a “SOS system limited Functionality” in a Range Rover is issues with the TCU. If the TCU has problems, you can easily diagnose the issue using a diagnostic tool. 

Connect the diagnostic tool to your vehicle and then scan for related error codes to the TCU. If any code is found, there could be an issue with the TCU or its connection. 

Below is how you could fix an SOS system limited Functionality issue.

1. Change the TCU battery

To change the TCU battery, you need first to locate the TCU. The TCU is situated in the trunk on the left side of the vehicle. To do this, follow the steps below. 

  • Take out the left side of the trunk 
  • Slide the cover on the right side and remove it. 
  • Pry open the small tab with a screwdriver to access the battery.
  • Disconnect the electrical connector and replace the battery with a new one. 
  • Replace damaged TCU 

The TCU system can be tricky to replace. Apart from replacing the module, you may need to have the module reprogrammed to be able to work for your vehicle. 

Repramming requires more sophisticated tools, which could be found in professional mechanics workshops. 

2. Fix the wiring harness 

To be able to fix a damaged wiring harness, you may need the owner’s manual to be able to find the particular wiring harness responsible for the SOS system. Once the wires are found, you must properly examine them for broken wires, corrosion, and other obvious damages. 

If any damage is found, you must replace the wires immediately to have the system running back. 

Final Thoughts 

The “Range Rover SOS system limited Functionality” may not have obvious symptoms. It is the reason many people tend to ignore the warning sign. If you find the waning signal on the dashboard, it is best to have the issue solved. This ensures you have total access to emergency services from your vehicle in case of an accident. 

  • Edmond Davis

    I'm Edmond Davis, an automotive expert with years of experience in vehicle repair, performance, and safety. I graduated from the University of Michigan with a degree in Automotive Engineering and have worked with major companies like Ford, GM, and Chrysler. I'm a trusted source of information for anyone looking to learn more about cars or improve their driving experience.

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