C1626 — Implausible Control

Causes

• Faulty wheel-speed, yaw-rate or steering-angle sensor
• Intermittent or damaged wiring/connector to ABS/VDC/ESC module or sensors
• Low or unstable battery/charging system voltage
• Hydraulic modulator/ABS pump or valve fault
• Faulty ABS/VDC/ESP control module (internal failure)
• Improper or missing sensor calibration after service (e.g., steering angle)

Symptoms

• ABS, ESC/VDC or traction control warning lamp illuminated
• Stability/traction control intervention is disabled or reduced
• Unexpected braking or ABS activation
• Loss of traction control or inconsistent ABS behavior during stops
• Diagnostic trouble codes present and stored in ABS/ESC module

What to check

• Read all stored DTCs and freeze-frame data from ABS/ESC and engine control modules
• Note any related codes (wheel speed, steering angle, yaw sensor, power supply, CAN/LIN bus)
• Visual inspection of wiring, connectors and sensor mounting for damage, corrosion or loose pins
• Check battery voltage and charging system (engine running and key-on)
• Scan live data: wheel speeds, steering angle, yaw rate, lateral acceleration, brake pressure and system status
• Verify CAN/LIN bus communications and module presence

Signal parameters

• Battery/charging: key on ~12.2–12.8 V, engine running ~13.5–14.8 V; voltage dips or noise may cause faults
• Wheel speed sensors: signals from all four corners should be consistent at a given speed (differences should be small — typically
• Wheel sensor frequency: increases smoothly with wheel speed; abrupt dropouts indicate sensor or tone ring issues
• Steering angle: sensor angle should correlate with steering wheel position and calculated angle from wheel speeds; mismatch of several degrees is suspicious
• Yaw rate and lateral acceleration: values should be consistent with vehicle speed and steering angle (large mismatch = implausible)
• ABS hydraulic pressure: pump/valve commands should produce measurable pressure pulses during actuation tests

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