Modern cars come with a variety of advanced systems aimed at making you a safer driver. One such system is Vehicle Dynamic Control (VDC), which ultimately is designed to improve traction.
When there is a problem with this system, you will see the VDC light come on to your dashboard.
In this article, we discuss the reasons the VDC light might come on and what you should do about it.
What Does VDC Light Mean?
“VDC” stands for Vehicle Dynamic Control, and the VDC light comes on when there is a problem with either the anti-lock brake and/or traction control systems.
Vehicle Dynamic Control (VDC) system engages with your vehicle’s anti-lock brake system to increase traction. When VDC engages, you may feel some vibration in the brake pedal.
This does not mean that there is a problem with the VDC system, it simply means that VDC is engaged and working with the anti-lock brake system.
Typically, the VDC applies brake force individually at the wheels to counteract slippage. If the vehicle happens to be understeering, your VDC will apply brake force on the outer front wheel to pull it back into a turn.
VDC will not steer the vehicle for you, but it will provide assistance to make the car easier to drive.
VDC is constantly monitoring the direction and steering of the vehicle. The VDC uses this information to determine the intended intent of the driver vs. the actual vehicle response.
If there are no deviations from what the driver intended, VDC does nothing. However, if there is a problem, the VDC system will assist to counteract the loss of traction and wheel slip.
What Does VDC OFF Mean?
Your vehicle has a VDC OFF warning indicator light on the dashboard. This warning light stays dark, as long as the stability control system is turned on.
When the VDC off indicator is lit, the system protection is off. This would occur if the driver turned the system protection off, or if the system has disabled itself due to a malfunction.
Your vehicle has a VDC OFF lights on your dash. These warning lights will usually remain dark as long as your vehicle’s stability control system is on.
If the VDC off indicator light is illuminated, that means that the driver has turned it off or that the vehicle has disabled it automatically due to a failure.
What Does VDC Do?
VDC is used to control the brakes individually at each wheel. The vehicle control module keeps track of wheel rotation speed and the direction of the steering wheel plus a few other parameters.
When the system recognizes that the vehicle is departing from the actual direction the driver is traveling from, then the VDC goes to work.
To illustrate how VDC works, let’s take oversteering as an example. Both front wheels are rotating at differing speeds, because the outer wheel speed is greater than the inner wheel speed. The difference in wheel speed can cause the car to spin out-of-control.
VDC will prevent this scenario when the outer front wheel brake is applied by VDC. Applying the brakes scrubs off speed on the outer wheel, which reduces the speed differential between both front wheels.
Some VDC models will also temporarily delivery less power to the output shaft. These VDC systems will either pull back on the throttle, delay the ignition spark timing, or do both at the same time. So, then drop in engine power allows the car to slow down and make the car much more controllable.
Causes of VDC Light
Common causes of a VDC light are a bad ABS wheel sensor, a bad steering angle sensor, or low brake fluid. It can also turn on if you go symptomatic on a low-quality road. In certain rare cases, a bad steering rack or a bad control module may contribute to a VDC light.
Here is a more detailed list of the common causes of a VDC light:
#1. Bad Wheel Sensors.
Each of your wheels has sensors attached that monitor speed and function. Whatever information these sensors relay is sent to the ECU, which processes all the information it receives.
For instance, if a wheel begins to slip that would cause it to spin quicker than the other wheels, the speed is measured and then relayed to the ECU to report that something is a problem.
The VDC then engages the system to reduce power to that particular wheel and provide improvement in traction.
If your wheel sensor were to become faulty, the proper information would not be sent and the VDC light would come on or illuminate with the indication that a wheel sensor is broken or has some sort of debris obstructing it from functioning properly.
#2. Bad Steering Angle Sensors.
Any wheel that has traction control is going to have steering angle sensors as well. Their purpose is to track the angle of the wheel while driving. However, the design of the sensors won’t hold up to getting dirty or, in some cases, fail altogether.
When the steering angle sensors become faulty or dirty, the vehicle dynamics control (VDC) light will come on. You will notice this more than likely happened even when you are driving on a smooth, clear surface where you have not needed the traction control.
#3. Low Brake Fluid.
Additionally, low brake fluid is a common issue that makes the VDC light come on. As your brakes wear down, the brake fluid will continue to get lower and lower in the reservoir even if there is no fluid leak.
When you change the brake pads and push the brake caliper in, the fluid will rise back to the appropriate levels.
You should check the fluid reservoir in the engine compartment and add brake fluid if it is low.
#4. Low-Quality Roads.
The VDC system is effective at holding stability when traveling over slippery surfaces. But, if the conditions become severe, this too can trigger the system to become faulty.
If you are traveling over ice and snow, you may see the VDC light illuminate briefly until traction is recovered, but you should not have any other issues causing the light to come on when you begin driving normally again.
#5. Bad Steering Rack.
The steering rack is the mechanical component that allows the vehicle’s wheels to turn in response to input from the steering wheel, which is mounted to the steering system on the body of the vehicle.
The steering rack is a hydraulic component that uses fluid to turn the wheels. If the steering rack fails, or is malfunctioning, you could then have trouble steering the vehicle which may cause the VDC light to come on.
#6. Bad ECU.
The car has many sensors constantly sending messages to the car’s computer. The computer is what takes information from the data being sent to it from the sensors and translates it into real-life action.
For example, once the wheels start to slip, the ECU has to cut power to the wheel for correction.
Yet, the ECU may not always work correctly, and always read the messages from the sensors, and when that doesn’t happen, the ECU may trigger the VDC light.
How to Deactivate VDC Light?
To deactivate the VDC light, you must first determine the cause. If the light is illuminated simply because of the road, you’re driving on, it should turn off once driving conditions return to normal—this means that no action is needed.
If the VDC light is illuminated because of a bad sensor, you will need to change the sensor. Sometimes, the sensors can be cleaned, which provides some cost savings. A mechanic will also check the wiring of the sensors to make sure everything is properly working.
But if your car needs a new steering rack or a new ECU, that’s a more expensive repair job. The steering rack can be tricky to replace because it takes time to fix. The ECU, to get a proper reprogram, will also need a professional.
First and foremost, the easiest way to deactivate a VDC light is to check the brake fluid level and replace it if it’s low. Then read the trouble codes if you have a diagnostic scanner.
Check for any technical service bulletins or recalls for your specific car. For example, some Infiniti car models have technical service bulletins related to the VDC light.