Engine Control Module Case Study

Case Synopsis: The front of a commercial truck collided with the rear of a passenger vehicle that had slowed for congested traffic. No injuries were immediately reported and damage to the truck was minimal. Police cited the truck operator with various violations and, after they cleared the scene, allowed the truck operator to continue his trip to his home terminal. Although reporting nothing to police regarding his vehicle, the truck operator advised maintenance personnel that he heard an air leak coming from his truck and that the brakes on the company’s trailer had failed preventing him from stopping in time to avoid the collision. For unspecified reasons, maintenance personnel replaced various brake system components on the incident trailer. Subsequently, the truck operator sued the trailer company for injuries and wage loss suffered as a result of the collision citing defective trailer brakes as the cause of the incident and thus his injuries.

Expert Analysis: Plaintiff retained a local truck mechanic that reviewed the service records documenting the post-incident brake service, as well as the plaintiff’s testimony, and authored two reports explaining how and why the post-incident repairs proved there was a brake malfunction that caused the incident. Despite any physical evidence or explanation for why the components were replaced, the expert correlated the post-incident repair to the alleged air leak, and in turn, to the alleged trailer brake failure. However, plaintiff ignored certain important facts regarding commercial truck air brake system operation in forming his opinions. Overlooked was the fact that the trailer brakes and tires would have locked immediately had an air leak occurred in the manner the plaintiff testified it did.

Defense experts conducted a series of tests based on the plaintiff’s own testimony that demonstrated the effect the alleged air leak would have had on vehicle braking. Using the truck’s on-board engine control module (ECM) as a data collection and recording tool, vehicle speed, brake application timing, and deceleration rates were recorded and calculated. The results disproved plaintiff’s allegations that the air leak, occurring where plaintiff testified it did, had no effect on vehicle braking performance. The testing also rebutted plaintiff’s expert’s theory that the air leak would have resulted in a complete loss of brakes by demonstrating the fail-safe, automatic trailer brake application resulting from loss of air pressure.

Result: After arbitration, the case settled for a small fraction of plaintiff’s initial demand.