TCS Switch: Traction Control Button Deactivation and the System Behind It

About TCS Switch, Traction control is no longer an optional feature in vehicles because it provides safety when driving on slippery roads. 

But most cars have a TCS switch to turn off the feature if you want to engage in sporty maneuvers. These include drifting when racing past corners.

Turning off the feature can also help you drive out of sticky situations when you get stuck in heavy snow or mud.

Here’s how the system works and the symptoms of a TCS switch failure.

Table of Contents

What Is a TCS Switch?

A TCS switch is a button that controls or enables you to deactivate the traction control system

Its placement or position can vary depending on the vehicle’s make and model, but the symbol drawn on it is standard.

It is a car with two wavy lines following its wheels to indicate skidding. Also, it has the word “off” below the image.

Symptoms of a TCS Switch Failure

If this switch fails, you can experience these four symptoms when driving.

Illuminated Traction Control Light

This light turning on doesn’t always mean the TCS is faulty. It can light up briefly when you turn on the engine or if the wheels lose traction by spinning quickly. 

However, if the light remains on for a while, the switch might be faulty.

An illuminated traction control light

An illuminated traction control light

Remember, the function of this switch is to deactivate the TCS feature. And it indicates the system is off by turning on the traction control light. 

Therefore, it can turn off the system when faulty, making the light remain on.

Illuminated Check Engine Light

A faulty traction control switch that turns off the TCS can trigger the check engine light to turn on.

In most cases, you’ll get the error codes P0856 or P0858 when you scan the ECU for diagnostic trouble codes using an OBD-II scanner.

An illuminated check engine warning light

An illuminated check engine warning light

If the switch is okay, check its connector and wiring to the powertrain control module.

Unresponsiveness

A bad traction control switch might be unresponsive, preventing you from turning off traction control when stuck or racing.

So, you might think you’ve turned off the feature, but it will be running in the background. Therefore, it will apply brakes when you don’t need this assistance.

This failure will be particularly disadvantageous if you’re stuck in the mud or heavy snow; you won’t be able to get out.

Stuck Switch

Dirt and drinks like coffee and juices can also damage the TCS switch. They can cause it to stick in the depressed position, making the traction control system remain off. Or they can short or corrode the contacts.

You can solve this issue by removing and cleaning the button or replacing it if it has shorted inside.

A person pressing the TCS switch

A person pressing the TCS switch

Depending on the car make and model, replacing this unit can cost anywhere from $20 to $100.

How Traction Control Works

Let’s take a step back to explain how this system works so that you know why it is dangerous to drive when off.

The traction control system became a standard safety feature in all vehicles built after 2011. This standardization became effective in all vehicles sold in the United States after 2012.

This system is part of the electronic stability control. It gets activated when the throttle input, engine power, and torque transfer (driving speed) don’t match the road surface conditions.

The difference in stability with traction control on and off

The difference in stability with traction control on and off

It intervenes in the vehicle’s operations by applying one or more of the following actions.

  • Applying brakes to one or more wheels
  • Cutting fuel supply to one or more cylinders
  • Reducing or suppressing the spark sequencing in one or more cylinders
  • Actuating the boost control solenoid in turbocharged engines to cut engine power
  • Closing the throttle in drive-by-wire systems

In most cars, the system cuts engine torque and brakes on one or more wheels. It does so because it shares the electro-hydraulic brake actuator and wheel speed sensors with the anti-lock braking system.

So, if it detects one wheel spinning faster than the others, it activates the ABS control unit to stop it. This braking will transfer more power to the wheel axle with more traction.

You might feel the brake pedal pulsate and see the dashboard ABS light turn on.

The ABS dashboard warning light

The ABS dashboard warning light

Traction Control in AWD Cars

Traction control activation in AWD cars will lock the system tighter in full-time AWD systems. This locking supplies more torque to the non-slipping wheels.

However, in part-time AWD systems, traction control engages the electronically controlled coupling in the transaxle or transfer case. This action sends more power to the wheels with grip.

Traction Control vs. Anti-Lock Braking

These two systems are interlinked and share actuators and sensors. But they are not the same. Here’s how they compare.

Purpose

The traction control system prevents wheel spin when you drive on slippery surfaces, such as muddy and snowy roads. 

So, its purpose is to help you control the vehicle by minimizing skidding. It brakes individual wheels and adjusts engine torque output to achieve that objective.

But the antilock brake system enhances braking performance by preventing wheel lockup when you press the brake pedal hard. 

Otherwise, the wheels would lock and skid, making it impossible to steer the vehicle.

An ABS control unit in the engine bay

An ABS control unit in the engine bay

Operation

TCS monitors the wheel speed sensors to get traction and wheel speed data. 

If it detects wheel slippage, it cuts engine power and brakes the slipping wheels. This action sends more torque to those with grip.

ABS also reads data from the wheel speed sensors. But it modulates the braking pressure if it senses the wheel is about to lock and skid.

Conditions for Activation

Traction control becomes active when the system detects wheels slipping during acceleration using wheel speed sensor data.

But ABS kicks in when you brake hard or apply emergency brakes. 

The system helps maintain steering control in dry and wet driving conditions, while TCS sends more torque to the wheels with grip.

A hydroplaning car with vs. without ABS

A hydroplaning car with vs. without ABS

Wrap Up

As you can see, the TCS switch is vital for controlling the traction control system in modern vehicles.

Although the TCS is on by default, the switch can turn off if faulty. This deactivation makes you drive with zero stability on slippery or loose surfaces.

If you need to replace this button or want to redo the wiring, we can help you source the parts. Contact us or comment below, and we’ll get the details.