It happens when you least expect it. You start your Land Rover LR3, LR4, or Range Rover Sport, and suddenly the dashboard lights up like a Christmas tree.
"HDC Fault System Unavailable" appears on the screen. The ABS light is on. The Traction Control light is on. The suspension lowers to access height. Your car says "Special Programs Off".
In the Land Rover community, this phenomenon is famously known as "The Three Amigos" (referring to the three warning lights). It looks like a catastrophic failure, but it’s often just a $20 part.
Stop guessing. Today, we’ll use the iCarsoft LR V4.0 to find the exact culprit.
The "Three Amigos" Killer
Why Does "HDC Fault" Disable Everything?
Land Rovers are highly integrated. The HDC (Hill Descent Control) needs to know exactly how fast each wheel is turning. If the computer gets confusing data from even one sensor, it panics. For safety, it shuts down:
- ABS (Anti-lock Brakes)
- Traction Control
- Air Suspension (lowers to be safe)
- Terrain Response System
The result is a scary dashboard, but the car is usually mechanically fine.
The 3 Most Common Causes
1. Weak Battery (The #1 Suspect)
If your battery voltage drops below a certain threshold during startup, the sensitive ABS module throws a tantrum.
Diagnosis: Use your iCarsoft LR V4.0 to check voltage. If you have codes for "Low Voltage" in multiple modules, charge or replace your battery first. (See our Battery Guide).
2. Brake Light Switch ($15 Fix)
Believe it or not, a cheap plastic switch under your brake pedal is a common failure point. If the car thinks you are braking when you aren't, it throws an HDC fault.
Diagnosis: Go to Live Data in the ABS module. Look for "Brake Switch Status." Press the pedal. If the status doesn't change from "Off" to "On" instantly, the switch is dead.
3. Wheel Speed Sensor ($40 Fix)
Each wheel has a sensor that counts rotation. Mud, rust, or a broken wire can kill it.
Diagnosis: This is where the iCarsoft LR V4.0 pays for itself.
1. Run an "Auto Scan".
2. Look for a code like C1A93 (Rear Right Speed Sensor Circuit).
3. Verify with Live Data: Select "Wheel Speed" for all 4 wheels. Drive slowly (5 mph) in a straight line. If three wheels show "5 mph" and one shows "0 mph", you have found the bad sensor!
Steering Angle Sensor (SAS) Issues
Sometimes, if your steering wheel isn't perfectly straight when driving straight, the car gets confused. This often happens after an alignment.
The Fix: Use the iCarsoft LR V4.0 SAS Calibration function.
Menu: Service > SAS > Land Rover.
Follow the instructions (usually centering the wheel and holding it steady). This resets the "zero point" and often clears the lights instantly.
Don't Pay Dealer Prices for a $20 Sensor
A dealership will charge $150 just to plug in their computer and tell you it's a speed sensor. With the iCarsoft LR V4.0, you can diagnose it in 2 minutes and fix it yourself.
Fix Your Dashboard Lights Now
