DTC U3004-16: Acc Relay Circuit Malfunction (BCM): Outline

WARNING: This page is about a different car, the 2020 Mazda CX-30. However, it is still accessible from the selected car via links, so may be relevant.

DTC U3004:16 (BCM) DETECTION CONDITION AND POSSIBLE CAUSE

System malfunction location	ACC relay circuit malfunction
Detection condition	The body control module (BCM) detects that the ACC monitor voltage is lower than the standard.
Fail-safe	Not applicable
Possible cause	ACC relay malfunction Short to ground or open circuit in ACC relay power supply circuit Body control module (BCM) connector or terminal malfunction Short to ground or open circuit in ACC relay monitor circuit Body control module (BCM) malfunction
Courtesy of MAZDA MOTORS CORP.