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Home / DTC / U0520 — Invalid Data Received From Vehicle Dynamics Control Module

U0520 — Invalid Data Received From Vehicle Dynamics Control Module

Detailed page for trouble code U0520.

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U0520

Generic U — Network/User

Invalid Data Received From Vehicle Dynamics Control Module

Brand: Generic
Type: U — Network/User
Views: UK: 3 EN: 6 RU: 3
AI status
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Page language: EN

Causes

  • Corrupted CAN messages from VDC module (bad checksum, wrong length, invalid data)
  • Intermittent or failed CAN physical layer (open/shorted wires, poor connector/crimp)
  • Failed VDC module or internal software/firmware error
  • Incorrect or mismatched software/calibration in VDC or another module
  • Low or unstable battery/ground voltage affecting module operation
  • Aftermarket devices or wiring taps loading the CAN bus

Symptoms

  • ABS, traction control or stability control warning lamp(s) illuminated
  • Reduced or altered brake/traction/stability functionality
  • One or more communication-related U-codes present
  • Intermittent operation of VDC-controlled features
  • Possible drivability complaints if VDC data used by engine/transmission controls

What to check

  • Read and record all diagnostic trouble codes (scan all modules) and freeze frame data
  • Check for other module U-codes that indicate broader CAN bus issues (U0100, U0121, etc.)
  • Inspect battery voltage and main grounds for proper connections and cleanliness
  • Visually inspect VDC module connector and CAN wiring for damage, corrosion, or loose pins
  • Use scan tool to monitor VDC messages and data stream for validity and update rate
  • Measure CAN bus termination resistance across CAN_H and CAN_L (≈60 ohms typical)

Signal parameters

  • CAN recessive voltage: CAN_H ≈ 2.5 V, CAN_L ≈ 2.5 V (both reference to chassis)
  • CAN dominant voltages: CAN_H ≈ 3.5 V, CAN_L ≈ 1.5 V (differential ≈ 2.0 V)
  • Typical CAN bus termination: two 120 Ω resistors in parallel (~60 Ω total)
  • Common bus speeds: 250 kb/s or 500 kb/s (verify vehicle-specific rate before replacement)
  • Expected VDC message frequency: typically repeated periodically (example 5–20 Hz depending on signal)
  • Watch for excessive BUS ERROR counters and CRC/checksum failures in message frames

Diagnostic algorithm

  1. Retrieve all codes and freeze-frame data. Note occurrence pattern (ignition cycles, driving conditions).
  2. Check battery state of charge and main chassis/engine grounds. Repair as needed and clear codes.
  3. Visually inspect the VDC module connector and CAN wiring harness for damage, corrosion, pin push-out, or aftermarket splices.
  4. With a scan tool, observe live data from the VDC module and other modules that use VDC data. Confirm whether VDC messages appear and if values are plausible.
  5. Check for related U-codes on other modules (indicative of bus-wide failure). If many U-codes present, focus on CAN physical layer.
  6. Measure resistance between CAN_H and CAN_L with ignition off; expect ~60 Ω. If outside tolerance, locate open/short/removed termination.
  7. Use an oscilloscope or CAN bus analyzer to inspect CAN_H and CAN_L waveforms while engine is running and when fault occurs. Look for missing frames, dominant/recessive anomalies, noise, or malformed frames.
  8. Isolate the VDC module: disconnect the VDC connector and check whether bus behavior changes and other modules still receive valid data. If disconnecting VDC clears invalid data but creates 'module not present' codes, the VDC unit likely transmits corrupted frames.
  9. If wiring and bus physical layer are good, perform module software level checks: verify calibration/software levels for VDC and related modules; reflash/update if required.
  10. If tests point to a failed VDC module, consider replacement or repair. After replacement or repair, clear codes, recheck communications, and road-test to confirm resolution.
  11. If intermittent, perform wiggle tests on wiring and connectors while monitoring bus traffic to reproduce the issue.

Likely causes

  • Damaged or corroded connector at VDC module
  • Wire short between CAN_H and CAN_L or short to battery/ground
  • Failed VDC module transmitter circuitry
  • Missing or incorrect CAN termination resistor
  • Software mismatch after module replacement or update

Fault status

⚠️ Status
Invalid/corrupted messages received from the Vehicle Dynamics Control module. CAN frames may have incorrect length, checksum/CRC failures, unexpected data, or timing errors. Communication integrity between VDC and other modules is compromised.
🟡 Repair difficulty: Medium
⏱️ Diagnostic time: 1-4 hours

Similar codes

U0100 U0121 U0140 U0155 U0420
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