C0584 indicates a low voltage condition in the B‑phase of the brake‑booster motor’s U, V, and W circuits. The power supply to the brake‑booster motor is insufficient, causing the system to detect an abnormal condition.
Corroded connectors, damaged harness, or broken wires can cause a voltage drop that triggers the low‑voltage condition.
A shorted or open winding within the motor itself can prevent proper voltage from being delivered.
A blown or high‑resistance fuse will limit voltage to the motor, resulting in the code.
Insufficient grounding can cause the circuit voltage to drop below the threshold.
The module that drives the motor may have internal faults that misinterpret voltage levels.
Very rarely, the power‑train control module can misread the circuit; this is a last‑resort consideration after all hardware has been verified.
No. The PCM is rarely the cause of C0584. Replace it only after confirming that all wiring, fuses, motor, and control module are functioning correctly.
Yes. A blown or high‑resistance fuse in the B‑phase circuit will reduce voltage and trigger the code.
A reset will turn off the MIL temporarily, but the code will return if the underlying low‑voltage condition remains.
No. The brake‑booster motor is an electric actuator that provides additional boost, while the brake‑assist pump (if equipped) is a separate hydraulic component.