DTC B1478: Retained Accessory Power (Rap) Circuit High: Description
WARNING: This page is about a different car, the 2001 GMC Safari and 2001 Chevrolet Astro. However, it is still accessible from the selected car via links, so may be relevant.
Retained Accessory Power (RAP) function allows radio, power windows and driver information center (if equipped) to operate with doors closed and ignition off for up to 20 minutes. BCM monitors ignition switch position, door jamb switches and voltage on RAP relay control circuit. BCM will command RAP relay ON by grounding RAP relay control circuit. DTC B1478 will set, when BCM detects battery voltage on RAP relay control circuit with ignition switch in RUN position. BCM detects battery voltage when RAP is commanded off. These conditions must be met for 0.5 seconds.