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Home / DTC / U0543 — Invalid Data Received From Headlamp Control Module “B”

U0543 — Invalid Data Received From Headlamp Control Module “B”

Detailed page for trouble code U0543.

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U0543

HYUNDAI U — Network/User

Invalid Data Received From Headlamp Control Module “B”

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

Causes

  • Faulty Headlamp Control Module “B” (internal failure)
  • CAN (or LIN) bus communication errors or high bit-error rate
  • Damaged wiring or connectors (broken wires, corrosion, water intrusion)
  • Poor power supply or ground to the headlamp control module
  • Faulty or missing termination resistor on the CAN bus
  • Intermittent short to voltage or ground on network lines

Symptoms

  • Malfunction Indicator Lamp (MIL) or warning lamp illuminated
  • Headlamps not working correctly (flicker, stuck on/off, reduced brightness)
  • Adaptive/auto-leveling headlamp functions disabled or erratic
  • Dashboard message indicating lamp/module fault
  • Other modules reporting related communication or data errors
  • DTCs stored for headlamp circuit or network communication

What to check

  • Use a full-function scan tool to read all stored and pending DTCs, and record freeze-frame data
  • Check for related U-codes or module communication faults (multiple modules)
  • Visually inspect headlamp connectors, wiring harness and module for corrosion, damage or water
  • Verify proper battery voltage and test ground at the headlamp control module
  • Check CAN/LIN wiring for continuity, shorts to battery/ground, and proper routing
  • Measure CAN_H and CAN_L voltages with key ON (idle ~2.5 V each; differential ~0 V idle, dominant ~2 V)

Signal parameters

  • CAN_H / CAN_L idle voltage: ~2.5 V on each line; differential ~0 V when recessive
  • CAN dominant differential: ~+2.0 V (CAN_H ~3.5 V, CAN_L ~1.5 V) during transmission
  • Typical message frequency: depends on vehicle network (headlamp status messages often 1–50 Hz)
  • Example data fields expected from Headlamp Control Module B: headlamp_status (0 = OK, 1 = Fault), left_beam_command (0–100% or discrete states), right_beam_command (0–100% or discrete states), adaptive_level (normalized value or degrees), turn_signal_state (off/left/right), error_flags (bitmask)
  • Expected status values: headlamp_status = OK (0) under normal operation; brightness values within 0–100% or defined discrete states

Diagnostic algorithm

  1. Connect a scan tool and capture all DTCs and freeze-frame data. Note related U-codes and module communication faults.
  2. Inspect the headlamp control module B connector and wiring for corrosion, damage, water, and secure mating. Repair any physical damage.
  3. With ignition on, monitor live data for headlamp module messages. Confirm whether the module is transmitting valid messages or producing out-of-range values.
  4. Check battery voltage and verify a good ground at the headlamp control module. Repair poor power/ground connections.
  5. Measure CAN_H and CAN_L voltages and use an oscilloscope if available to verify clean differential signalling and lack of noise/reflections.
  6. Measure bus termination resistance and continuity of CAN wires between modules; repair shorts/open circuits as needed.
  7. If wiring and bus are good, attempt to reprogram or update the headlamp control module software per dealer procedures/TBS and re-test.
  8. If the code persists after wiring, power, and software checks, consider replacing the headlamp control module B. If replacing, follow proper programming/coding procedures and recheck network for additional faults.
  9. After repairs, clear DTCs and verify proper function of headlamps and that the U0543 code does not return during road test and module communication monitoring.

Likely causes

  • Intermittent or failed CAN communication between BCM/IPC and Headlamp Control Module B
  • Corroded or loose connector at the headlamp control module or harness
  • Headlamp Control Module B internal fault
  • Power/ground fault at the headlamp module (low battery voltage, loose ground)
  • Software mismatch or required module reflash

Fault status

⚠️ Status
Invalid Data Received From Headlamp Control Module "B" — communications or data integrity issue detected. Check headlamp module power/ground, harness/connectors, CAN/LIN bus integrity, and module software.
🟡 Repair difficulty: Medium
⏱️ Diagnostic time: 1.0 - 3.0 hours

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371

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