Symptoms of a Bad or Failing Traction Control Switch

Traction control has evolved from being a luxury upgrade to a common OEM standard equipment item in recent years. The purpose of this system is to assist the driver in maintaining control of their vehicle when they are driving in bad weather conditions or when they encounter a quick maneuvering situation that requires emergency driving procedures. If a problem with this switch occurs, it may render the ABS and traction control system useless.

What is the traction control switch?

Traction control is a vehicle control system that is an enhancement of the Anti-Lock Brake System (ABS). This system works to prevent the loss of traction between the tires and the roadway. The traction control switch is typically located on the dashboard, steering wheel, or center console that when depressed sends a signal to the Antilock Braking System and monitors wheel speed along with braking action and sends this data to the ECU of the vehicle to be processed. The application of the traction control system occurs twice:

  • The driver applies the brakes: The TCS (traction control switch) will relay data whenever the tires start rotating at a speed that is faster than the speed of the vehicle (known as positive slip). This triggers the ABS system to be activated. The ABS will apply gradual pressure to the brake calipers in an effort to slow down the rate of tire rotation to match vehicle speed. This ensures that the tires maintain traction with the road.
  • Reducing engine power: On vehicles that utilize electronic throttle bodies, the throttle plate is closed slightly to reduce the amount of air entering the engine. By giving less air to the engine for the combustion process, less power is made by the engine. This decreases the amount of torque applied to the wheels, thereby slowing down the rotational speed of the tires.

Both instances help reduce the potential of a vehicle accident by automatically reducing the potential of having the wheels and tires locking up in hazardous situations. When the traction control switch works correctly, the system can function as intended for the lifespan of the vehicle. However, when it fails, it will cause a few symptoms or warning signs to occur. Noted below are a few of the common symptoms of a bad or damaged traction control switch which should alert you to contact a certified mechanic for inspection, service and replacement if needed.

1. Check Engine Light comes on

The traction control system constantly updates the ECM with data. If this component is faulty or damaged, it will usually trigger an OBD-II error code that is stored inside the ECM and triggers the Check Engine Light to appear. If you notice that this light or the traction control light comes on when the system is active, notify a local mechanic. A certified ASE mechanic will typically start the diagnosis by plugging in their digital scanner and downloading any error codes that are stored in the ECM. Once they find the right source of the error code, they will have a good starting point to begin their trace.

2. Car brakes inconsistently

The traction control switch is supposed to activate the ABS and wheel speed sensor that control the vehicle during non-typical driving situations. However, under serious and extremely rare situations, a broken traction control switch may send information to the ABS that causes a malfunction in this system. In some cases this means the brakes will be applied differently than they should (sometimes more aggressively, which can cause the tires to lock up, and other times not aggressively enough).

If this situation occurs, you should stop driving your car immediately and contact a certified mechanic to inspect and repair the issue as it is a safety concern and may lead to a vehicle accident.

3. Traction control switch does not depress

Most of the time, the problem with the traction control switch is attributed to function, meaning that you won't be able to turn it on or off. This is commonly caused by a traction control switch that is jammed with debris or has broken and won't depress. In this case, the mechanic will have to replace the traction control switch, which is a rather simple process.

Anytime you experience any of the above symptoms it is recommended to contact a local ASE certified mechanic so they can complete the right repairs that will ensure your traction control system works smooth for years.


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