Electric power steering (EPS) can stop working due to various electrical or mechanical faults within its sophisticated system, leading to a sudden loss of power assist and making steering difficult.
Understanding Electric Power Steering (EPS)
Unlike traditional hydraulic power steering systems that rely on a pump, fluid, and hoses, electric power steering systems use an electric motor to provide steering assistance. This motor is controlled by an Electronic Control Unit (ECU) that receives input from various sensors, such as torque sensors and steering angle sensors, to determine how much assistance is needed. This design is more fuel-efficient and allows for advanced features, but it is also susceptible to specific electronic and electrical issues.
Common Causes of EPS System Failure
When an electric power steering system stops working, it's typically due to one or more of the following issues:
1. Electrical Component Malfunctions
The heart of an EPS system is its electrical components. Failure in any of these critical parts can immediately disable the power assist.
- Electric Motor Failure: The electric motor is directly responsible for providing the steering assistance. If this motor fails due to internal wear, damage, or overheating, the EPS system will cease to function, leaving you with manual steering.
- Sensor Issues: EPS relies heavily on sensors to determine driver input and vehicle speed.
- Torque Sensor: Detects how much force the driver is applying to the steering wheel. A faulty torque sensor can send incorrect signals or no signals at all, causing the ECU to either provide no assist or inconsistent assist.
- Steering Angle Sensor: Measures the steering wheel's position and rate of turn. Problems with this sensor can lead to the system not knowing how much or in what direction to apply power.
- Electronic Control Unit (ECU) Problems: The ECU acts as the brain of the EPS system, processing sensor data and controlling the electric motor. If the ECU experiences an internal fault, software glitch, or loses power, it cannot command the system properly, leading to a loss of power steering.
- Wiring and Fuse Problems: Damaged wiring, corroded connectors, or a blown fuse in the EPS circuit can interrupt the power supply to the motor or the communication between the ECU and other components, effectively shutting down the system.
2. Battery and Charging System Issues
A healthy vehicle electrical system is crucial for EPS operation.
- Low Battery Voltage: The EPS motor requires a significant amount of electrical power. If the vehicle's battery is weak, failing, or if the alternator is not charging it properly, there might not be enough voltage or current to power the EPS motor, causing it to stop working or perform intermittently.
- Alternator Failure: A malfunctioning alternator prevents the battery from charging and supplying consistent power to the vehicle's electrical systems, including EPS.
3. Software Glitches
Modern EPS systems often involve complex software.
- Firmware Bugs or Corruptions: Just like any computer system, the ECU's software can experience bugs, errors, or become corrupted, leading to incorrect operation or complete shutdown of the power steering assist.
4. Physical Damage
External factors can also impact the EPS system.
- Impact Damage: A collision or hitting a large pothole can physically damage EPS components, wiring, or even the steering column itself, affecting the system's functionality.
- Water Ingress: Exposure to water, especially in components not properly sealed, can cause short circuits or corrosion, leading to electrical failures.
Common Symptoms of EPS Failure
If your electric power steering is failing, you might notice:
- A sudden increase in effort required to turn the steering wheel, especially at low speeds or when stationary.
- A warning light illuminating on your dashboard, often showing a steering wheel icon, sometimes accompanied by an exclamation mark.
- Intermittent loss of power assist, where steering becomes heavy and then lightens again.
- Unusual noises coming from the steering column area, such as humming or clicking, though this is less common with EPS compared to hydraulic systems.
What to Do When EPS Fails
If your electric power steering stops working:
- Reduce Speed: As steering becomes significantly harder, reduce your speed and proceed with caution.
- Pull Over Safely: If possible, find a safe place to pull over and stop the vehicle.
- Check for Warning Lights: Note any dashboard warning lights.
- Restart the Vehicle: Sometimes, a simple restart can temporarily reset a minor electronic glitch. If the power steering returns after a restart, it's still advisable to have it checked.
- Seek Professional Diagnosis: Due to the complexity of EPS, it's crucial to have a qualified mechanic diagnose the issue. They can use specialized diagnostic tools to read fault codes from the ECU and identify the exact cause of the failure.
Understanding the potential causes helps in identifying the problem and seeking appropriate repairs to restore the ease and safety of your vehicle's steering.
