C0580

Code

Generic C — Chassis

Brake Booster Motor A Phase U-V-W Circuit Low

Brand: Generic

Type: C — Chassis

Views: UK: 23 EN: 37 RU: 23

AI status

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Page language: EN

Causes

Open circuit or high resistance in U/V/W phase wiring or connector
Short to ground or short to battery on a phase conductor
Failed electric brake booster motor (winding short/open)
Faulty motor driver / ABS/Brake ECU output stage
Low battery voltage or poor battery/ground connections
Corroded or damaged connector pins or terminal shorts

Symptoms

ABS, traction control, or master warning lamp illumination
Reduced or lost electric brake assist; unusually hard brake pedal or altered pedal feel
Brake system fault messages on dash (electric booster fault)
Stored ABS/brake module DTCs and possible limp-home mode
Intermittent faults that may appear under load or vibration

What to check

Read and record DTC(s) and freeze-frame data with a compatible scan tool
Verify battery voltage and charging system under rest and under load (engine running)
Visually inspect motor connector, pins, and wiring for corrosion, damage, or water entry
Wiggle-test wiring harness while monitoring live data or observing code occurrence
Check fuses, relays, and any inline connectors for the booster motor supply
Measure continuity and resistance of each motor phase (U, V, W) to each other and to ground/B+ with connector disconnected

Signal parameters

Control: three-phase PWM outputs from brake/ABS control module (multi-level switching)
Supply: system battery voltage present at motor supply/relay when booster is commanded (~battery voltage; consult OEM)
Phase-to-phase resistance: typically low (low ohms range); consult vehicle-specific service data
Expected waveform: switching/PWM on all phases when motor commanded; absence or DC low indicates low circuit condition
If a phase is shorted to ground, measured voltage will be near 0V; if shorted to B+, measured voltage will be near battery potential

Diagnostic algorithm

Verify C0580 present and note freeze-frame and related DTCs (check for accompanying supply or CAN faults)
Check battery state and charging system; ensure battery >= 12.4V (engine off) and charging normally with engine running
Turn ignition off and disconnect negative battery terminal if required by manufacturer before working on high-current circuits
Visually inspect booster motor connector and harness for damage/corrosion; repair corroded terminals as needed
With connector disconnected, measure resistance between motor phase terminals (U-V, V-W, U-W) and compare to service spec; look for open circuits or significant imbalance
Check resistance from each phase to chassis ground and to battery positive to detect short to ground or B+
Reconnect and with a scan tool command the booster motor while observing live data or using an oscilloscope to view PWM on phase outputs from control module; if PWM present but motor phases low, suspect wiring/connectors or motor
If control module outputs are missing, test for supply power and proper grounds at module; inspect module power fuses/relays
If wiring and supply are good but the motor does not respond and phase resistances are out of spec, replace or bench-test the booster motor assembly
If outputs from the brake/ABS module are faulty (no PWM or stuck low/high) after wiring verification, consider module repair/replacement per OEM procedures
After repairs, clear codes and perform functional test/road test to confirm diagnosis and that code does not return

Likely causes

Damaged phase wire insulation chafed to chassis (short to ground)
Loose or corroded booster motor connector or poor terminal contact
Failed motor driver inside brake ECU due to overheating or water intrusion
Low battery or weak charging system causing supply dropout when motor is commanded
Open or very high-resistance motor winding

Fault status

⚠️ Status

Electric brake booster motor A phase circuit voltage below expected threshold (U-V-W). May reduce electric brake assist; fault stored by brake/ABS control module.

🟡 Repair difficulty: Medium

⏱️ Diagnostic time: 1.0-4.0 hours

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