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Home / DTC / U0047 — Vehicle Communication Bus C Performance

U0047 — Vehicle Communication Bus C Performance

Detailed page for trouble code U0047.

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Code

U0047

HYUNDAI U — Network/User

Vehicle Communication Bus C Performance

Brand: HYUNDAI
Type: U — Network/User
AI status
Completed
ready
Completed 100%
Page language: EN

Causes

  • Damaged or corroded wiring or connectors on Bus C
  • Short to battery or ground on CAN/LIN wires
  • Open circuit or intermittent connection in bus wiring
  • Missing or failed termination resistor(s)
  • Failed or malfunctioning control module attached to Bus C
  • Water ingress or mechanical damage to connectors or modules

Symptoms

  • Multiple modules report communication errors or go offline
  • Warning lights or communication-related messages on cluster
  • Loss of functions controlled by Bus C (doors, HVAC, BCM features)
  • Intermittent operation of accessories or erratic module behavior
  • Possible no-crank / no-start if critical modules are affected

What to check

  • Read all modules with a diagnostic scanner and record U-codes and freeze frame
  • Inspect Bus C wiring harness, connectors, and module grounds for damage or corrosion
  • Verify battery voltage and charging system health
  • Measure DC resistance between CAN_H and CAN_L (power off) — approx. 60 Ω typical with two 120 Ω terminators in parallel
  • Check for short to 12V or ground from CAN/LIN wires (back-probe pins with meter)
  • Visually inspect and, if applicable, remove moisture/debris from connectors and modules

Signal parameters

  • CAN recessive: CAN_H ≈ 2.5 V, CAN_L ≈ 2.5 V (no dominant bits)
  • CAN dominant: CAN_H ≈ 3.5 V, CAN_L ≈ 1.5 V (differential ≈ 2 V)
  • Typical bus idle differential ≈ 0 V to low-level noise; dominant pulses when active
  • Termination: two 120 Ω resistors (one at each end) giving ~60 Ω end-to-end
  • Message presence: key module IDs and periodic messages should be observed on Bus C (use scope or CAN sniffer to confirm)

Diagnostic algorithm

  1. Connect a factory or full-function scan tool, read all modules and note additional U-codes and timestamps.
  2. Check battery voltage and charge state; ensure stable power during diagnosis.
  3. Inspect connectors, harnesses, and module grounds on Bus C for corrosion, damage, or loose pins; repair as needed.
  4. With ignition off, measure resistance between CAN_H and CAN_L at a convenient connector — expect ~60 Ω. If far off, disconnect modules one at a time to locate short or open.
  5. Back-probe CAN_H and CAN_L with a lab scope or CAN logger with ignition on. Look for proper recessive/dominant voltages and clean waveform. Note missing IDs or excessive noise.
  6. Isolate segments: unplug suspect modules or remove connectors to see if the fault clears, indicating a module or harness fault.
  7. Check for shorts to 12V or ground on the bus wiring; repair insulation or replace wiring as necessary.
  8. If a single module is suspected, verify power/ground to that module and, if available, swap with a known-good unit or consult manufacturer guidance before replacement.
  9. Check for relevant TSBs or software updates; perform module reprogramming if recommended by manufacturer.
  10. After repairs, clear codes, cycle ignition, and test drive while monitoring Bus C messages to confirm the fault does not return.

Likely causes

  • Open/shorted CAN_H or CAN_L (or LIN) wiring between modules
  • Failed module driving the bus (transceiver fault)
  • Corroded connector or pin causing intermittent connection
  • Incorrect or missing termination resistor (120 Ω per end)
  • Intermittent power/ground to one or more Bus C modules

Fault status

⚠️ Status
Vehicle Communication Bus C performance fault — disrupted or degraded communications detected on Bus C. Multiple modules may be unresponsive or reporting communication errors.
🟡 Repair difficulty: Medium
⏱️ Diagnostic time: 1.0-3.5 hours

Similar codes

U0073 U0100 U0101 U0115 U0121
371

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