Patent ID: 7609069
Filing Date: 2009-10-27
Classification: G01R

Abstract:
1. A method for testing the operation of a hydraulic solenoid valve having a valve solenoid of a vehicle control system, wherein the valve solenoid is connected between a power supply and a drain terminal of a Field Effect Transistor (FET), the FET also having a source terminal connected to ground and a gate terminal, the FET being responsive to a voltage applied to the gate terminal to switch between conducting and non-conducting states, wherein: the valve is an analog valve operative in a Pulse Width Modulated (PWM) mode in which a PWM voltage is applied to the FET gate with the method including the following steps: (a) sensing the supply voltage and the FET drain voltage during one of either the conducting or non-conducting state of the FET; (b) calculating the ratio of the FET drain voltage to the supply voltage; and (c) comparing the resulting ratio to a threshold to determine whether the solenoid coil is operative.