Open potentiometer detection system

A method of determining a failure of a potentiometer having a resistive element coupled between a voltage input and ground and an adjustable arm determining a resistance of the resistive element, the method comprising:

• setting a first driver output coupled to the voltage input of the potentiometer to a first value;
• reading, while the voltage input of the potentiometer is set to the first value, a first sample voltage from the adjustable arm, and determining whether the first sample voltage is between a high threshold and a low threshold value, wherein the high and low threshold values represent highest and lowest voltages, respectively, of the potentiometer as used in a system in which a failure of the potentiometer is being determined;
• setting the first driver output coupled to the voltage input of the potentiometer to a second value that is lower than the first value;
• applying a voltage to the adjustable arm via a second driver output and a low pass filter including a capacitor;
• and
• reading a second sample from the adjustable arm and determining whether the second sample is below an arm threshold value, wherein the arm threshold value represents a minimum voltage when the adjustable arm is moved to ground.

A method of determining a failure of a potentiometer having a resistive element coupled between a voltage input and ground and an adjustable arm determining a resistance of the resistive element using a controller having a first driver output and a second driver output, the method comprising:

• coupling the first driver output to the voltage input of the potentiometer and coupling the second driver output to the adjustable arm via a low pass filter including a capacitor;
• setting the first driver output coupled to the voltage input of the potentiometer to a first value;
• reading, while the voltage input of the potentiometer is set to the first value, a first sample voltage from the adjustable arm after a delay determined by a time constant of the low pass filter;
• determining whether the first sample voltage is between a high threshold and a low threshold value, wherein the high and low threshold values represent highest and lowest voltages, respectively, of the potentiometer as used in a system in which a failure of the potentiometer is being determined;
• setting the first driver output coupled to the voltage input of the potentiometer to a second value that is lower than the first value;
• applying a voltage to the adjustable arm via the second driver output and the low pass filter;
• reading, while the voltage input of the potentiometer is set to the second value and while the voltage is applied to the adjustable arm via the second driver and the low pass filter, a second sample from the adjustable arm after a delay determined by the time constant of the low pass filter;
• and
• determining whether the second sample is below an arm threshold value via the controller, wherein the arm threshold value represents a minimum voltage when the adjustable arm is moved to ground.