Automotive Throttle by Wire Problems

Automotive Throttle by Wire Problems
Car throttle with shallow depth of field on a white background

Automotive throttle by wire systems have come a long way in the last five years. Although the system is now more reliable than first-generation systems, there remains plenty of room for improvement. Here we’ll discuss how Electronic Throttle Control (ETC) works and review common problems associated with automobiles that utilize the technology.

Why We Need ETC

Car throttle with shallow depth of field on a white background

Automobile manufacturers have been chomping at the bit to roll out electronic actuator controlled throttle systems for decades. The advantage from their point of view is the ability to remove the driver from throttle decisions in certain situations. Things like smart cruise control, stability safety systems, traction control and anti lock brakes systems are now able to close the throttle when necessary. Although this is essentially ignoring the driver’s request it enhances safety in panic situations when drivers are likely to make poor decisions.

Throttle by Wire Operation

Electronic throttle control replaces the manual cables that use to connect between the gas pedal and the throttle plate. This physical connection is now completed using sensors, wiring and a control module. To be more specific, they mount a throttle position sensor in the gas pedal. This variable potentiometer sends the current throttle position to the control module where the signal is analyzed. From the module, they send voltage to a control motor mounted in the throttle body. This actuator carries out the command to open the throttle plate, thereby allowing more air to flow into the engine. The action increases RPMs and power output. Using the control module as the middleman allows the computer to use other input variables in the decision-making process. As an example, the cruise control system no longer needs the complicated servos and actuators since the computer is capable of holding the throttle open in the right position when the cruise switch is activated.

GM Electronic Throttle Control Problems

Like many new systems the electronic throttle control has hit a few bumps in the road. For General Motors the problem has been most evident on their full size light-duty truck line from 2001 through 2009. Problems with the actuator motor in the throttle body or the throttle position sensor mounted near the butterfly has caused a wide variety of complaints from motorists.Warning lights in the dash seem to provide the first clue that something is going wrong. Drivers have reported traction control, service stability track and engine power reduced lights coming on intermittently. Although individual instances of these warning lights will have to be diagnosed on a case-by-case basis, often the failure is a malfunction in the throttle body. Unfortunately the actuator and throttle position sensor that can fail are not serviced separately. Complete replacement throttle body units are in the range of $250-$400 depending on the year, make and model and where the parts originate from.

Chrysler Throttle Control Issues

Chrysler products are not immune from problems with the drive by wire system. However, what is different on Chrysler automobiles is they have a separate electronic throttle control light. The ETC light will come on when a malfunction is detected. A check engine light with a throttle position sensor code set in memory can also occur. Also different from GM, the throttle position sensor is replaceable depending on the year make and model. In some cases, motorists will have to tow the vehicle in for service when complete throttle body failure occurs, because the throttle plate will not open.

Automotive Throttle by Wire Headlines

Some companies like Toyota and Audi have had their share of bad press from either sudden acceleration syndrome or throttle control problems where the automobile performed an action that was not expected. The complaints in these cases started to surface before a problem was identified. When Toyota drivers began to complain, the motor company’s investigation led them to believe interference with the floor mat was the culprit. In 2002 the national Highway traffic safety administration (NHTSA) contracted NASA scientists to study the issue. In the end they could not confirm or deny that a software problem was responsible for the unintended acceleration or that the problem actually occurred as they were unable to reproduce it in regular driving situations. In October 2013 a grand jury returned a verdict finding Toyota liable in the case of a collision in 2007. In the end throttle by wire systems will make it past these bumps in the road just like the mass air flow sensor and other automotive components that didn’t work perfectly when they were initially launched.