B1971 Code: Meaning, Causes, and Symptoms | OBD2 Codes

B1971 – Inadvertent Power Fault


B1971 Possible Symptoms


Engine Light ON (or Service Engine Soon Warning Light)


B1971 Possible Causes


Faulty Inadvertent Power Relay,Inadvertent Power Relay harness is open or shorted,Inadvertent Power Relay circuit poor electrical connection,Faulty Body Control Module (BCM)


B1971 Description


If interior lights are accidentally left on, a Delayed Interior Lighting (DIL) feature provides automatic shutoff. The DIL relay is an integral component of the multifunction relay. When the ignition switch is in RUN position, The Body Control Module (BCM) continuously keeps output to DIL relay active. When the ignition switch is turned to OFF position, BCM will deactivate DIL relay output after 10 minutes. The 10-minute time-out period resets anytime BCM wakes up and any of the following states are detected: – A door is opened or closed, or driver door unlock message is received. – The trunk is opened or closed. – Interior lights are turned on. When DIL relay is energized, power is supplied to interior lights and high side of the interior light relay coil. The BCM continuously monitors output to DIL relay. The Diagnostic Trouble Code (DTC) B1971 will set when output is commanded on or off, and short or open is detected for at least 2 seconds. When DTC B1971 is set, BCM will continue to command the requested state of relay until it is achieved or no longer necessary. DTC B1971 will clear when conditions for fault no longer exist or when scan tool is used. A history DTC will clear after 50 consecutive ignition cycles if conditions for fault no longer exist.