A method for detecting faults in an electro-hydraulic control system for a transmission, comprising: initiating a delivery of fluid to the electro-hydraulic control system, adjusting regulator control signals that request a main regulator valve of the electro-hydraulic control system to develop a main line pressure, in which adjusting regulator control signals comprises generating regulator control signals that request the main regulator valve to increase the main line pressure from a nominal level to a first pressure level and regulator control signals that request the main regulator valve to increase the main line pressure from the first pressure level to a second pressure level, receiving status signals that indicate status of a pressure switch of the electro-hydraulic control system, status of the pressure switch being based upon the main line pressure, detecting faults based upon regulator control signals requesting the main line pressure to increase to the first pressure level or the second pressure level and status signals indicative of status of the pressure switch at the corresponding first pressure level or second pressure level, in which detecting faults based on regulator control signals comprises detecting a fault of the electro-hydraulic control system in response to status signals indicating the pressure switch is in an inactive state and regulator control signals requested the main regulator valve to increase the main line pressure to the first pressure level, and in which detecting faults based on regulator control signals further comprises detecting a fault of the electro-hydraulic control system in response to status signals indicating the pressure switch is in an active state and regulator control signals requested the main regulator valve to increase the main line pressure to the second pressure level, and generating one or more diagnostic signals that are indicative of detected faults. initiating a delivery of fluid to the electro-hydraulic control system, adjusting regulator control signals that request a main regulator valve of the electro-hydraulic control system to develop a main line pressure, in which adjusting regulator control signals comprises generating regulator control signals that request the main regulator valve to increase the main line pressure from a nominal level to a first pressure level and regulator control signals that request the main regulator valve to increase the main line pressure from the first pressure level to a second pressure level, receiving status signals that indicate status of a pressure switch of the electro-hydraulic control system, status of the pressure switch being based upon the main line pressure, detecting faults based upon regulator control signals requesting the main line pressure to increase to the first pressure level or the second pressure level and status signals indicative of status of the pressure switch at the corresponding first pressure level or second pressure level, in which detecting faults based on regulator control signals comprises detecting a fault of the electro-hydraulic control system in response to status signals indicating the pressure switch is in an inactive state and regulator control signals requested the main regulator valve to increase the main line pressure to the first pressure level, and in which detecting faults based on regulator control signals further comprises detecting a fault of the electro-hydraulic control system in response to status signals indicating the pressure switch is in an active state and regulator control signals requested the main regulator valve to increase the main line pressure to the second pressure level, and generating one or more diagnostic signals that are indicative of detected faults.