3 ms·

It's kind of funny that now that everything in a car is effectively software-controlled something like a mechanical ignition switch is still left to control a m

by yason 13y ago

It's kind of funny that now that everything in a car is effectively software-controlled something like a mechanical ignition switch is still left to control a main circuit that's so crucial it will stop the engine if broken. To think, we do have wireless car keys already, with just a start/stop button on the instruction panel. Even with physical keys I would assume that this particular circuit would be controlled via a relay and the car computer would only let the driver to stop the engine by removing the key if the car was not moving.

moioci 13y ago
In the news over the last couple of years, I've seen more than one report of schoolchildren stopping a runaway school bus (driver passed out, etc.) by turning off the ignition key. So this behavior can be a feature, not a bug.
- yason 13y ago
  Turning off the engine doesn't have to be attached to the mechanical ignition switch. There are already cars where the ignition switch is completely wireless and software-controlled. For example, many cars offer a start-stop feature which turns the engine off when standing in red lights and automatically starting it again the foot moves from brake pedal to the accelerator. People are going to learn that there's no such thing as ignition switch anymore. Motorcycles have red kill switches that shut down the engine completely. A school bus or a car could have something like that.
Mister_Snuggles 13y ago
It really depends on the car. My car, for example, is a Chrysler 300 and there is no real connection between the key and what provides power to the engine. Here[1] is a diagram showing how the CAN bus works on the Chrysler/Dodge LX platform vehicles. The SCM/SKREEM module on that diagram is where the ignition switch and logic that talks to the keyfob is and makes sure you have a valid key. Here's a recall related to the module which hints a little bit about what it is and does[3]. Note on the recall that this applies to a whole bunch of Dodge/Chrysler platforms. Based on the wiring diagram[2] (for Dodge trucks, which is one of the platforms that [3] applies to), the SCM/SKREEM (called Node-Wireless Ignition in one diagram and WCM in another) uses a 2-wire CAN bus for its communication. Once the SCM/SKREEM validates the key it sends a message on the CAN bus to the engine controller to tell it to start the engine. In these vehicles, whether the engine is on or off is purely under software control. That said, I'm not going to try turning my car off while I'm driving. [1] http://the8thlayerof.net/2013/11/10/canbus-vehicle-network-data-capture-tapping-the-can-network-wires-chrysler-lx-platform-2006-dodge-charger-srt8/ http://the8thlayerof.net/2013/11/10/canbus-vehicle-network-d... [2] http://tucrrc.utulsa.edu/DodgeCAN.html http://tucrrc.utulsa.edu/DodgeCAN.html [3] http://project-jk.com/images/tsb/TSB_08-007-08.pdf http://project-jk.com/images/tsb/TSB_08-007-08.pdf
rcxdude 13y ago
Given how Toyota has had the opposite problem, I would not be comfortable if the engine could not be stopped in this manner.

by yason 13y ago

moioci 13y ago

In the news over the last couple of years, I've seen more than one report of schoolchildren stopping a runaway school bus (driver passed out, etc.) by turning off the ignition key. So this behavior can be a feature, not a bug.

yason 13y ago
Turning off the engine doesn't have to be attached to the mechanical ignition switch. There are already cars where the ignition switch is completely wireless and software-controlled. For example, many cars offer a start-stop feature which turns the engine off when standing in red lights and automatically starting it again the foot moves from brake pedal to the accelerator. People are going to learn that there's no such thing as ignition switch anymore. Motorcycles have red kill switches that shut down the engine completely. A school bus or a car could have something like that.

Mister_Snuggles 13y ago

It really depends on the car. My car, for example, is a Chrysler 300 and there is no real connection between the key and what provides power to the engine. Here[1] is a diagram showing how the CAN bus works on the Chrysler/Dodge LX platform vehicles. The SCM/SKREEM module on that diagram is where the ignition switch and logic that talks to the keyfob is and makes sure you have a valid key. Here's a recall related to the module which hints a little bit about what it is and does[3]. Note on the recall that this applies to a whole bunch of Dodge/Chrysler platforms. Based on the wiring diagram[2] (for Dodge trucks, which is one of the platforms that [3] applies to), the SCM/SKREEM (called Node-Wireless Ignition in one diagram and WCM in another) uses a 2-wire CAN bus for its communication. Once the SCM/SKREEM validates the key it sends a message on the CAN bus to the engine controller to tell it to start the engine. In these vehicles, whether the engine is on or off is purely under software control. That said, I'm not going to try turning my car off while I'm driving. [1] http://the8thlayerof.net/2013/11/10/canbus-vehicle-network-data-capture-tapping-the-can-network-wires-chrysler-lx-platform-2006-dodge-charger-srt8/ http://the8thlayerof.net/2013/11/10/canbus-vehicle-network-d... [2] http://tucrrc.utulsa.edu/DodgeCAN.html http://tucrrc.utulsa.edu/DodgeCAN.html [3] http://project-jk.com/images/tsb/TSB_08-007-08.pdf http://project-jk.com/images/tsb/TSB_08-007-08.pdf

rcxdude 13y ago

Given how Toyota has had the opposite problem, I would not be comfortable if the engine could not be stopped in this manner.