TIE-IN WITH ABS, VSC SYSTEMS
As I mentioned earlier, drive-by-wire electronic throttle control offers many options for engineers as they design modern-day vehicles and embrace even more driver aids — especially when combined with anti-lock brakes, computer-controlled transmission and vehicle stability control all tied together in a controlled area network. Just recently, Mazda announced it would be adding the technology needed to enable engine shutdown if the PCM sees a request for throttle and brake at the same time to prevent unintended acceleration. That alone wouldn’t be possible without drive-by-wire throttle, nor would they have been able to eliminate the idle air control motor or cruise control diaphragm.
While those advantages alone are good reasons to go with drive-by-wire, it really shines when it’s tied into the Dynamic Stability and Traction Control systems and, I would expect, future accident-avoidance systems. With all the control units communicating, we have vehicle speed, individual wheel speeds and steering angle inputs available to us. Add in the recently included lateral acceleration and vehicle rotation or “yaw” sensors and the computers can now compare the driver’s input to what the vehicle is actually doing.
If the sensors indicate that the driver could use some help to maintain control, electronic throttle gives the stability control system another option. In the event the vehicle is under-steering or pushing, the system can now reduce engine power as well as apply the inside rear brake with the ABS system to help the driver regain control, or the outside front if an over-steering or loose condition is sensed to bring the rear of the car under control.
The same applies to traction control; through a combination of brake application and power reduction, the slipping wheels can be controlled to maintain traction and control. None of these systems would exist without the active controls made possible by electronically controlled systems.
As you’ve come to expect from my articles, this won’t make you a Mazda specialist, but I hope it does make you more comfortable taking on these fine cars as they find their way into your bays. I also hope it helped remove some of the apprehension you feel when faced with the drive-by-wire systems that are becoming more common.
If there is one thing you take from this article, it should be that since you have Internet access at the shop, get in the habit of using it as an essential part of the diagnostic process. Information to help speed your diagnostic process is out there, and it’s foolish not to use it.