Chassis, generic

C0584 Brake Booster Motor B Phase U-V-W Circuit Low

Check engine lightUsually off
EmissionsNot relevant
Drive cycleNot required
Limp modePossible

C0584 means a phase of booster motor B is held too low – shorted to ground, a lower transistor that will not switch off, or a driver whose gate supply has collapsed. No manufacturer publishes the code in its booster meaning; it shows up only in GM's older keyword list (PIP5094), where the number belonged to another system. Gate drivers such as TI's DRV8343-Q1 test every phase for a short to ground while the bridge is disabled, and the DRV8305-Q1 reports when its charge pump falls too far below the motor supply. With two independent winding systems, as in the Hyundai Mobis patent, a fault in one system must not pull down the other, so the module isolates side B and, where the design allows, keeps braking assist going on side A.

Likely causes

Phase lead of side B shorted to ground or housing
Lower transistor of power module B shorted
Gate-driver supply of channel B too low

Symptoms

  • Brake system warning and possibly reduced assist
  • Driver assistance braking functions may be limited

Repair estimate

DifficultyHardWorkshop job
Parts and labour€150–2,800
Time1–4 h

Typical range across vehicles; the real cost depends on what the testing finds.

Parts involved

brake booster motor bmotor phase wiring

Related codes

C0583C0585C0586C0580C0593

References: ti.com, ti.com, patents.google.com, static.nhtsa.gov.