Patent ID: 8436623

Claim:
An electromagnetic load circuit failure diagnosis device in which a high-side switch element is connected on a side of a power supply voltage terminal of an electromagnetic load provided between the power supply voltage terminal and a ground, a low-side switch element connected on the ground side, the high-side switch element and the low-side switch element opened/closed by a control signal of a switch element driving signal generating circuit, the failure diagnosis device comprising: failure diagnosis means that detects a layer short-circuit failure in which the high-side switch element, the low-side switch element or the electromagnetic load short-circuits with the power supply voltage terminal or the ground in a state of having a predetermined impedance, and performs a failure diagnosis, wherein the failure diagnosis means performs a layer short-circuit failure diagnosis during the period when a current is conducted through the electromagnetic load by the control signal of the switch element driving signal generating circuit, and detects a layer short-circuit failure by comparing the number of on/off operations of chopping of the high-side switch element or the low-side switch element with a predetermined number of times that is a failure diagnosis threshold.