Range Rover HDC system not available system fault: how to diagnose and fix

One of the Range Rovers I had gave me more than enough trouble because of its HDC system. At one point I was having panic attacks at the site of the most inconsequential incline.

Maybe it wasn’t really that bad, but I know the frustration that comes with encountering a problem with your beloved vehicle, especially when it’s the HDC (Hill Descent Control) System.

Lets take you through the steps to identifying and — hopefully — solving the HDC System issue.

What models are affected?

Signs and symptoms

The HDC System is designed to assist drivers when moving down steep hills.

So, whenever there is an issue with this system, drivers may notice the following signs:

  • A message on the dashboard display indicating “HDC System not available,” “HDC System Fault,” or “HDC System Failure.”
  • The system may activate at random speeds, causing the brakes to function slowly.
  • The ABS Control may activate with speed wheel sensor fault codes.
  • The battery may drain faster than usual.

List of possible OBD codes

Some common OBD (On-board diagnostics) codes that are relevant to Range Rover HDC System not available system fault include:

  • C1119-19– HDC Brake System: Pressure Accumulator Valve Circuit Failure.
  • U0402-00-Invalid Data Received from TCM/BCM.
  • P111F-63-HDC Light Control Valve Circuit Failure.

Please note that these codes may vary based on the specific model and year of the Range Rover.

Common causes

The causes of the HDC System not available system fault vary, but the most common ones are:

  • Electrical Faults: This could be caused by damaged wiring or a faulty sensor.
  • Control Module Failure: This occurs when the HDC Control Module has failed, and replacement is necessary.
  • Low Battery Voltage: When the battery voltage is low, the HDC system may be unable to function correctly.
  • Software Issues: In rare instances, software glitches can cause the HDC System not available system fault.

Can it be fixed without a mechanic?

To fix the HDC System not available system fault, you need a certain level of expertise in Range Rover mechanics.

However, if you are willing to put in the work and research, you can indeed fix the issue without a mechanic.

Parts you’ll need to fix it

Before diving into the steps, ensure you have the following parts:

  • HDC Control Module replacement (in case of Control Module Failure).
  • Wiring harness and connectors (in case of Electrical Faults).

Tools you’ll need to fix it

  • Socket set and ratchet.
  • Wrench Set.
  • Multimeter.
  • Techstream Diagnostic Tool.
  • HDC Brake Proportioning Valve Bleeder Kit.

How to fix it

1. Begin by identifying the issue, which could be electrical faults, control module failure, low battery voltage, or software issues.

2. If the problem is with the HDC Control Module, replace it with a new replacement.

3. If the issue is caused by electrical faults, inspect the wiring harness and connectors to make sure they are not damaged.

4. If the battery voltage is low, begin by checking the battery and charging system. Ensure the battery terminals and cables are clean, and the battery is completely charged.

5. Use the multimeter to check for voltage at the brake light switch, as it could also be the cause of the issue.

6. Use the Techstream Diagnostic Tool to reset any DTCs and re-initialize the HDC System.

7. Bleed the HDC Brake Proportioning Valve to ensure all air is out of the system.

Potential alternative causes (not mentioned above)

In some cases, the HDC System not available system fault could be caused by:

  • Failed brake light switch.
  • Failed brake booster.
  • Failed battery.


What is HDC?

HDC stands for Hill Descent Control, which is a system that helps drivers navigate steep slopes smoothly.

Why is my HDC System not available?

The HDC System not available system fault is generally caused by electrical faults, control module failure, low battery voltage, or software issues.

Can I still drive my Range Rover with the HDC System not available?

While it is still possible to drive with the HDC System not available, it is not recommended as it poses a risk to both passengers and the vehicle.

How can I prevent HDC system issues?

Regular maintenance of your Range Rover will help prevent HDC system issues. It’s recommended that you change the brake fluid every two years to maintain the system.


Range Rover HDC System not available system fault is a frustrating issue that can affect the smooth functioning of your vehicle. While the issue may have multiple causes, this troubleshooting guide and step-by-step guide can provide a solution.

If you follow these instructions and consult a professional when necessary, you can fix this issue and get your vehicle running at full capacity.

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