The airbag diagnostic module (or control unit) does a lot more than monitor your safety restraint system. This electronic component has evolved from a series of inertia switches and triggers to an Event Data Recorder (EDR), similar to those found in airplanes. This unit, first of all, isn’t black. Second of all, this unit is fast becoming one of the most important pieces of equipment in a car today. With the ability to record events and circumstances, manufacturers, lawyers and governments are all vying for both control and accessibility to these units.
Although Diagnostic Control Units have been in vehicles since 1976, they have only been recording data since 1994. The amount of data they collect is currently determined by each manufacturer. EDRs record between 5 and 20 seconds of data both prior to and subsequent to a crash event. The information they collect includes data such as vehicle speed, throttle position, brake switch position, gas pedal position, tire pressure warning lamp mode, ignition switch logic, transmission selector position, service engine lamp mode, outside temperature, door status (all 4), cruise control mode, engine speed, antilock brake system mode, steering angle and yaw rate (if equipped). All of this information is used by law enforcement, accident recreation professionals, lawyers and engineers, each for their own purposes.
The most recent controversy has been the Toyota worldwide recall for “sudden acceleration”. Toyota is one of the companies that, in the past, has not allowed software to access their ACUs (Airbag Control Units). A recent article released by AP (Associated Press) indicated that there was only one laptop in the entire US that was capable of reading Toyota event data. The article indicated that the data belonged to Toyota and that Toyota either refused to provide key information, settled pending lawsuits or provided printouts with the key columns blank when forced to provide access or event data. Subsequent to the media frenzy over the sudden acceleration incidents and recall, Toyota issued a press release addressing these concerns and provided both NHTSA as well as Transport Canada. Over 150 laptops capable of reading these vehicles have been released to other authorities.
But it’s not just Toyota that has issues with the ‘black box”. Ford has a unique issue discovered during the capture of data during an investigation. Some 2005 and later Ford vehicles have an additional event data recorder in the Powertrain Control Module (PCM). If airbags or seat belt pretensioners deployed, these vehicles are designed to store vehicle speed, brake on/off, ABS on/off, accelerator pedal position, and other parameters for 20 seconds before the crash and 5 seconds after the crash at 0.2 seconds intervals. But the problem Ford is experiencing is related to the data locking signal which is supposed to set after a crash with an airbag deployment. Electrical shorts caused by a crash or complete power loss in the vehicle can prevent this signal from being sent. As these recorders are designed to ‘continuously overwrite themselves’ the crash data may be lost if the key is not shut off within 25 seconds of a crash event.
There are documented instances where there was a severe crash, vehicle power was lost, but a well meaning investigator restored power to check other functions in the vehicle. In doing so, they unintentionally overwrote the event data and spoiled the only evidence available detailing the crash event timing and data.
Currently, the following manufacturers have event data recorders in the ACUs (this list may already be incomplete at of the time of this publishing).
Dodge
Chrysler
Jeep
Ford
Lincoln
Mercury
Buick
Cadillac
Chevrolet
Geo
Oldsmobile
Pontiac
Saturn
GMC
Hummer
Saab
Holden
Sterling
Mitsubishi
Isuzu
Suzuki
Toyota
Lexus
Scion
What the Future Holds
New legislation by the US government has mandated that all vehicles produced by 2012 must include an event data recorder. As most of us do not actually read the laws pending in our government, here is some of the legislation that they have voted on and passed.
The Secretary shall initiate a rulemaking proceeding requiring that the event data recorders required to be installed in passenger vehicles…-
(1) be temperature, water, crash, and tamper resistant; and
(2) continuously record vehicle operational data that can be accessed for retrieval and analysis
Specifications- The rule--
(1) shall require such recorders to record, for a reasonable time before, during, and after a crash or airbag deployment, information that includes engine performance, steering, braking, acceleration, vehicle speed, seat belt use, and airbag deployment level, deactivation status, deployment time, and deployment stage, and may require such recorders to record other data, such as data related to vehicle rollovers, as the Secretary considers appropriate;
(2) shall require such recorders to record data for at least 60 seconds prior to, and 15 seconds after, a crash or airbag deployment;
(3) may require such recorders to capture certain events such as rapid deceleration, full-throttle acceleration lasting more than 15 seconds, and full braking lasting more than 10 seconds, even if there is not a crash or airbag deployment;
(4) may not require information recorded or transmitted by such data recorders to include the vehicle’s location;
(5) shall require that data stored on such recorders be accessible, regardless of vehicle manufacturer or model, with commercially available equipment; and
(6) shall specify data format requirements and other requirements, and shall require an interoperable data access port to facilitate universal accessibility and analysis.
The upside to this is that all of us will have proof positive of the events that led up to and after a crash event. Certain aspects of liability will be determined more easily and driver error will quickly be assessed.
The downside of this is these new units are estimated to cost between two and three times more than the current diagnostic units. This will once again raise the cost of our vehicles substantially, increase insurance costs and increase the rate of total losses from vehicle damages.