Your Car's Computer Can Be Used Against You In A DUI Crash

In every DUI related car crash information about the speed of the vehicle, whether brakes were pressed prior to impact and other relevant evidence is often crucial in proving gross negligence.  In recent years the police have been getting creative in downloading data from the cars computer or SDM ( sensing diagnostic module) during their investigation. An SDM can provide important information about how the car was being driven moments prior to impact.

In one recent published opinion, People vs. Diaz, the Court noted the following:

"Every vehicle with air bags has an air bag control module that monitors a developing crash and, based on the information received, decides whether to deploy the air bags.   In addition, the module runs a diagnostic examination to make sure that its system is operating properly.   The module also has a function that records data and, after a crash, stores some of that data in the EDR, which is a component of the air bag control module.   For General Motors Corporation vehicles, this module is known as a sensing diagnostic module (SDM)․  In addition to recording such matters as the warning lamp status (which, when lighted indicates problems) and whether the driver's belt is buckled, an EDR captures information about the severity of a crash, known as the delta force or the change of speed, and the duration of the crash.   Moreover, the EDR records and stores four matters for a five-second period before a crash event—the vehicle speed, the engine revolutions per minute (RPM), the brake switch status (whether the brake has been applied), and the throttle position.“The SDM, which is controlled by a microprocessor, has multiple functions:  (1) it determines if a severe enough impact has occurred to warrant deployment of the air bag;  (2) it monitors the air bag's components;  and (3) it permanently records information.   The SDM contains software that analyzes the longitudinal deceleration of a vehicle to determine whether a deployment event has occurred based on testing that was done previously to determine what events would require protection by an air bag.   When the SDM senses an event (either a deployment event or an event that is not severe enough to require an air bag—that is, a near-deployment event), that information is recorded to the microprocessor's electrically erasable programmable read-only memory (EEPROM).   When the air bag is deployed, the SDM records the event as a ‘Code 51.’)   If the data from an EDR is properly evaluated, it can provide an impartial source of evidence for the reconstruction and biomechanics community to utilize"