Now that winter has come and gone (Sorry I bought new powder skis.), how was your winter driving experience? Many of you are driving vehicles with some type of traction enhancing system. At the simplest level a basic two wheel drive vehicle (be it front or rear wheel drive) when equipped with an antilock braking can also have a traction control system.
How do you know if your vehicle has traction control? Above and beyond feeling and hearing it work, the other way to know is recognizing the system’s warning lamp in the instrument cluster. This warning lamp is orange. It may be an almost circle with an arrow on one end surrounding a triangle with an exclamation mark in the middle. It may be a caricature of a vehicle with a two squiggly tire tracks behind it. I know there are others but these are the most common.
When you turn your car on and then start it these lights, like the rest of the warning lights, should come on for a short time and then go off. This is called a bulb check and also a system check. If the light does not go off the system is not working and requires repair. If the light does not turn on at all it is also very likely that the system requires repair and again is non functional.
A basic traction control system is an addition to an anti lock brake system. The anti lock brake system releases or holds brake pressure (applied by the driver from the brake pedal) at the individual brakes at each wheel or pair of wheels to stop the wheel or wheels from skidding. A traction control system adds the function of applying brake pressure to the individual driven wheels without any brake pedal input from the driver.
If a driven wheel starts to spin, that wheel is automatically braked (without driver input) and the axle system then transfers the driving force to the other wheel that is not spinning yet. If the other wheel starts to slip then it is braked and power flow is directed back to the other wheel again.
The effectiveness of this system is limited. In its original guise a driver with a heavy foot would still likely end up with alternating spinning tires and going no where. In the last fifteen years most vehicles have become drive by wire. I wrote about this in a previous article. Our throttle pedals are no longer connected to the throttle plate that allows air into the engine as we desire. Now our movement of the gas pedal is only an electronic request to open the throttle plate.
More modern traction control systems are therefore able to ignore our throttle request when it is unreasonable. Asking for too much power falls on deaf ears so to speak. The traction control system reduces power in order to stop the wheels from spinning.
As you can imagine or you may already have noticed these traction control systems are not perfect. In certain conditions we want to spin our tires especially when snow is deep and extra slippery.
It would be nearly impossible to move without spinning a tire. Some traction control systems will do just that. You can put your vehicle in gear at a standstill and the vehicle will not even rotate a tire.
Sometimes a little slipping will get your vehicle to move to an area where there may be a little more traction. Sometimes a very slippery section is coming up ahead and we need some more speed. We will accept a lack of control with a little more acceleration.
Thankfully most vehicles are equipped with a button to disable the traction control. That may be just what you need to get yourself moving from a standstill or let you get a run at that steep section.
Trail’s Ron Nutini is a licensed automotive technician and graduate of mechanical engineering from UBC. E-mail: email@example.com