C0596

Code

Generic C — Chassis

Brake Booster Motor A Current Sensor Circuit Range/Performance

Brand: Generic

Type: C — Chassis

Views: UK: 20 EN: 19 RU: 16

AI status

Completed

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Page language: EN

Causes

Open or short in the current sensor wiring or connector
Corroded, loose or contaminated connector or poor ground
Faulty brake booster motor current sensor (shunt, Hall or integrated sensor)
Failing brake booster motor drawing abnormal current (mechanical binding or electrical fault)
Faulty motor driver or brake control module (ECU/BCM)
Low battery voltage or poor charging system affecting sensor/readings

Symptoms

Brake/ABS warning lamp and/or traction control light illuminated
Reduced or no electric brake boost; harder brake pedal effort
Reduced braking performance or increased stopping distance
Store of related boost/ABS fault codes
Possible limp or reduced functionality of related regenerative/brake systems

What to check

Read and record freeze frame and live data with a scan tool; capture when fault is active
Verify battery voltage and charging system before testing (low voltage can cause false faults)
Visually inspect connectors and wiring at the brake booster motor and sensor for corrosion, damage, water ingress, and secure connections
Backprobe sensor connector and measure sensor output voltage while operating the booster (follow OEM safety procedures)
Measure motor current with an appropriate clamp meter during operation (compare to expected behavior)
Check continuity and resistance of wiring between sensor and module; check for intermittent opens by wiggling harness while watching live data

Signal parameters

Sensor type: analog current-sense (shunt or Hall) providing a voltage proportional to motor current or a CAN/serial message depending on design
Typical sensor output: proportional voltage in the module’s input range (commonly 0–5 V) — voltage increases with motor current
Expected behavior: near-zero output with motor off, steady proportional output when motor runs; may include PWM ripple from motor driver
Motor current: can be several amps to tens of amps under load (design-dependent) — use clamp meter for actual measurement

Diagnostic algorithm

Use a scan tool: retrieve C0596 and related codes, view freeze frame and live data while reproducing condition. Attempt to clear codes and see if they return.
Verify battery voltage and charging system (minimum stable voltage per OEM). Low voltage can create false current-sensor readings.
Visually inspect connectors, seals and wiring at brake booster motor and control module. Repair any corrosion, bent pins, or damaged insulation.
With service info in hand, backprobe the current sensor connector. Measure reference, ground and sensor output voltage with motor off and while commanding the booster (take safety precautions). Compare to expected values in service manual.
Measure motor current with a DC clamp meter while commanding motor operation. Compare measured current vs expected and observe for spikes, excessive draw or unusual behavior.
Check continuity/resistance of sensor wiring to module; look for short to battery or ground. Wiggle harness to check for intermittent faults.
If wiring and connectors are good but readings remain out of range, swap or bench-test the current sensor or replace the motor assembly per OEM procedure.
If motor and sensor bench tests are normal, suspect the motor driver or control module. Confirm driver outputs and communication; perform module reflash or replacement only after verifying upstream components.
After repairs, clear codes and perform a road or functional test to confirm the fault does not return.

Likely causes

Damaged or corroded connector at current sensor or motor
Faulty current sensor on brake booster motor
Wiring short/open between sensor and control module
High motor current due to mechanical binding in electric booster

Fault status

⚠️ Status

Stored when the brake booster motor A current sensor signal is outside the expected range or is not performing correctly. This may trigger brake/ABS warnings and reduce electric boost until the issue is resolved.

🟡 Repair difficulty: Medium

⏱️ Diagnostic time: 1-3 hours

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