DTC B1C84:12 [Front Body Control Module (FBCM)]: Notes

WARNING: This page is about a different car, the 2017 Mazda CX-5. However, it is still accessible from the selected car via links, so may be relevant.

DTC B1C84:12 (FRONT BODY CONTROL MODULE) DETECTION CONDITION AND POSSIBLE CAUSES

Description	Rear window defogger relay circuit malfunction
Detection condition	Front body control module (FBCM) detects a short to power supply in the rear window defogger relay circuit with the ignition switched ON (engine off or on).
Fail-safe function	Not applicable
Possible cause	Rear window defogger relay malfunction Front body control module (FBCM) connector or terminal malfunction Short to power supply in wiring harness between rear window defogger relay terminal E and front body control module (FBCM) terminal 1P Front body control module (FBCM) malfunction