On-board diagnosis of the drive circuit of an electronically controlled injector

Abstract

On-board diagnosis regulations, drive safety, and facility of service require that the engine control unit must detect malfunctions of the electronically controlled fuel injection system. For injector drive circuit faults, there are two types of fault definition in the Society of Automotive Engineers J2012 regulation, it is not enough to satisfy the above requirements. Through analysing the feedback current and voltage of the drive circuit under faulty and no-fault conditions and abstracting fault symptoms, this paper extends further the range of on-board diagnosis strategies, including an open circuit, a high-side drive short circuit to the low-side drive, a high- (or low-)side drive short circuit to the power supply, and a high- (or low-) side drive short circuit to the ground. After the circuit fault is confirmed, the diagnosis strategy can trigger an appropriate failure strategy to guarantee safety and to avoid emissions deterioration. In order to enhance the diagnosis reliability, the key constants of the diagnosis strategies are calibrated using a statistical method.