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Home / DTC / U0484 — Invalid Data Received From Lighting Control Module Rear “A”

U0484 — Invalid Data Received From Lighting Control Module Rear “A”

Detailed page for trouble code U0484.

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U0484

HYUNDAI U — Network/User

Invalid Data Received From Lighting Control Module Rear “A”

Brand: HYUNDAI
Type: U — Network/User
Views: UK: 25 EN: 42 RU: 25
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Page language: EN

Causes

  • Faulty Lighting Control Module (Rear A)
  • Poor connector or wiring (corrosion, bent pins, damaged insulation) at the LCM or intermediate junctions
  • CAN bus wiring short to ground or battery, or open circuit
  • Missing or incorrect termination resistor on CAN bus
  • Low or unstable battery/charging system voltage
  • Software mismatch or corrupted module programming

Symptoms

  • Rear lights (tail/brake/turn) may operate intermittently or not at all
  • Dash warnings related to exterior lighting or communication
  • Illuminated MIL or network-related warning lamps
  • Other body-control features may behave erratically if network traffic is affected
  • No communication with rear LCM using a scan tool or invalid data displayed

What to check

  • Use a scan tool to read all U-codes and freeze frame; check for multiple modules reporting communication issues
  • Visually inspect rear LCM connector and wiring harness for corrosion, damage, or loose pins
  • Verify battery voltage and charging system (>12.4 V at rest; >13.5 V running)
  • Check for correct CAN bus termination (approx. 60 ohms across CAN H and CAN L at rest)
  • Attempt to communicate directly with the rear LCM using OEM scanner and view live data
  • Backprobe the LCM CAN H and CAN L to observe voltage waveforms with scope or DMM (while cranking/running)

Signal parameters

  • CAN recessive state: both CAN H and CAN L ~2.5 V (nominal)
  • CAN dominant state: CAN H ~3.5 V, CAN L ~1.5 V (differential ~2.0 V)
  • Termination resistance: ~60 ohms measured across CAN H and CAN L with IGN off
  • Expected module response: rear LCM should appear on network and provide status frames at defined intervals (use OEM tool to view message IDs and frequencies)
  • Watch for stuck-high/low or noisy CAN lines and voltage dips below ~9–10 V during operation

Diagnostic algorithm

  1. Connect an OEM-level scan tool and record all stored and pending codes and freeze frame data. Note related network codes.
  2. Verify battery voltage and charging system condition. Repair charging/battery issues before communications troubleshooting.
  3. Clear code(s) and attempt to reproduce. If code returns, proceed with network diagnostics.
  4. Inspect the rear LCM connector and harness for corrosion, bent pins, water ingress, or physical damage. Repair or replace as required.
  5. Using a DMM or scope, measure CAN H and CAN L at the rear LCM connector with ignition on. Confirm recessive and dominant voltages and differential signals.
  6. Measure termination resistance across CAN H/L with ignition off (expect ~60 ohms). If incorrect, locate and repair missing/failed termination.
  7. Check for shorts to battery or ground on CAN H and CAN L (resistance to B+ or ground). Repair wiring faults.
  8. If wiring and bus integrity are good, attempt direct communication with the rear LCM via scan tool. If it does not respond or data is invalid while other modules are healthy, consider module fault.
  9. If available, update rear LCM software/firmware per OEM service procedure or reprogram module. Re-test.
  10. If fault persists after wiring and software verification, substitute a known-good rear LCM (or bench test/repair) and verify cure before replacing other components.
  11. After repair, clear codes and perform a road test/functional check of rear lighting and network stability.

Likely causes

  • Corroded/damaged connector or wiring at rear LCM
  • LCM hardware fault or internal failure
  • CAN bus short or open between rear LCM and main bus
  • Software/firmware mismatch after module replacement or update
  • Intermittent low voltage condition affecting module operation

Fault status

⚠️ Status
Invalid data received from Lighting Control Module Rear 'A' — communication frames are corrupted, out-of-range, or the module is not responding correctly on the vehicle network.
🟡 Repair difficulty: Medium
⏱️ Diagnostic time: 0.5-2.5 hours
84

Browse 84 HYUNDAI manuals: repair procedures, diagnostics, wiring diagrams, component locations, service data and Labor Times by year, model and trim.

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