Q: I read a recent article discussing GM's problems with their faulty ignition switch. You have given the advice in the past to turn off the ignition if the throttle sticks. This was mentioned several times when "unintended acceleration" was a common topic in the news. Does the information in this article change that advice?
A: Very timely and important question. In past columns I have written about how to deal with unintended acceleration/stuck throttle situations. In short, a driver has three tools to mitigate the threat of crashing: Push the brake pedal as hard as humanly possible, shift the transmission into neutral or turn off the ignition.
With the recent news regarding unintended "ignition off" scenarios in certain GM vehicles, it's well worth revisiting this issue.
First off, even if the engine is not running and the ignition switch is in the off position, the brakes and steering remain functional. Without power assist provided by engine operation, considerably more physical effort will be required to brake and steer the vehicle, but it will still stop and turn.
Shifting the transmission into neutral in response to the threat from a stuck throttle or unintended acceleration will disconnect the engine from the drivetrain while maintaining power assist to the steering and brakes. While it may seem potentially destructive to the engine, most modern engine management systems have limiters to prevent the engine from over-revving in neutral by cutting spark and/or fuel to limit engine speed.
Obviously, switching the ignition off will stop any type of unintended acceleration or stuck throttle. And doing so will not lock the steering. The ignition switch cannot be turned to the locked position unless the transmission has been shifted into park.
To address your specific question as to turning off the ignition in response to unintended acceleration or a stuck throttle, keep in mind that the air bags and supplemental restraint systems are not instantaneously disabled if the ignition is switched off. These systems have some type of backup power supplies in case the battery is disconnected or destroyed in the first instant of a crash. These systems, often based on a capacitor storing enough electrical charge to deploy the airbags, can keep the airbags operational for several seconds after loss of battery power — but just as obviously, not long enough to completely deal with an unintended acceleration or stuck throttle scenario.
With today's motor vehicles, the best response to unintended acceleration or some type of stuck throttle is to simply shift the transmission into neutral, deal with the situation by steering and braking to a safe stop and then turning off the key. Every motorist should mentally anticipate this scenario and understand the steps necessary to safely deal with it.
