Circuit Description
WARNING: This page does not describe the selected car, but rather 6 other vehicles, including the 2002 GMC Sierra, 2002 GMC Cab & Chassis Sierra, 2002 GMC C3500 HD, 2002 Chevrolet Silverado, and 2002 Chevrolet Cab & Chassis Silverado. However, it is still accessible from the selected car via links, so may be relevant.
Electronic Frontal Sensor (EFS) uses a unidirectional 2-wire circuit. EFS modulates current on the interface to send identification, State Of Health (SOH) and deployment commands to Sensing and Diagnostic Module (SDM). SDM provides power and ground to EFS. When ignition is turned on and power from SDM is detected by EFS, EFS performs internal diagnostics, then sends an identification message to EFS. SDM receives identification message within 5 seconds of power being turned on and determines if message is valid. EFS continually communicates a status message to SDM. When a fault is detected, SDM resets EFS twice by removing and reapplying power to SIS. If fault is still present, SDM will set applicable DTC.