U0484

Code

LAND ROVER U — Network/User

Invalid data received from the rear lighting control module B invalid

Brand: LAND ROVER

Type: U — Network/User

Views: UK: 17 EN: 27 RU: 24

AI status

Completed

ready

Completed 100%

Page language: EN

Causes

Faulty Rear Lighting Control Module B (internal failure)
Corroded/damaged connector or pin at RLCM B
Open/short in wiring between RLCM B and network supply or ground
CAN/LIN network fault (high/low voltage out of range, bus off)
Poor battery voltage or intermittent supply to module
Incorrect module programming/software mismatch after replacement or update

Symptoms

Warning messages or lamp icons on dash for rear lighting
Rear tail, brake, reverse or turn lights inoperative, intermittent, or behaving incorrectly
Other modules report related U-codes or ‘lost communication’ messages
Stored freeze frame data showing network voltage or runtime environment anomalies
Bulbs and fuses check OK but lights still faulty
Intermittent operation of rear lighting functions or permanent fail for one circuit

What to check

Read and record all stored DTCs and freeze frame data from the vehicle using a capable scan tool
Check for additional U-codes or CAN bus related codes in other modules
Inspect RLCM B connector for corrosion, bent pins, water entry, or damaged locking tab
Perform a visual inspection of rear harness and grounding points for chafing, corrosion or damage
Measure supply voltage and ground at RLCM B with connector connected and while operating rear lights
Verify CAN/LIN bus voltage levels at RLCM B (see signal_params) with key on and while operating affected functions

Signal parameters

CAN bus idle voltages ~2.5 V on CAN_H and CAN_L relative to chassis ground (should be close to each other)
Dominant CAN state: differential voltage present between CAN_H and CAN_L (approx 1.5–2.0 V differential)
Recessive CAN state: near 0 V differential, both lines ~2.5 V
Supply voltage to module: nominal battery voltage (~12–14.5 V) with ignition on
Ground continuity: low resistance (
Network message behavior: expected regular heartbeat messages from RLCM B; malformed or missing frames indicate data error (use a CAN analyzer)

Diagnostic algorithm

Connect a manufacturer-level scan tool and read all modules. Save codes and freeze frame. Note any other network codes.
Visually inspect RLCM B connector and nearby harness for corrosion, bent pins, water damage, or physical harm. Repair as necessary.
Check battery voltage and measure supply and ground at RLCM B with connector connected (key on). Confirm stable voltage under load.
Measure CAN_H and CAN_L voltages at the RLCM B connector with key on. Compare to signal_params. Look for stuck-high/low or excessive noise.
If voltages look normal, use an oscilloscope or CAN analyzer to capture traffic while operating rear lighting. Look for malformed frames, missing heartbeats, or bus collisions.
Perform a wiggle test on harness and connectors while monitoring for code changes or message dropouts to find intermittent faults.
Inspect and test other modules on the same network for related faults. Isolate the RLCM B by disconnecting it (only if safe and per manufacturer guidance) to see if the network stabilizes.
Verify module part numbers and software/calibration. If module was recently replaced or vehicle software updated, confirm correct coding and reprogram/reflash if required.
If wiring, supply, and network integrity are confirmed and issue persists, consider replacing RLCM B. Program and configure replacement module per manufacturer procedure.
Clear codes and perform a road test or operational cycles to ensure the fault does not return before closing repair.

Likely causes

Corroded or loose multi-pin connector at RLCM B causing data errors
Intermittent power or ground to RLCM B (voltage sag while driving)
Short to battery or ground on CAN/LIN wiring, pulling bus levels out of range
Module not coded or flashed to correct vehicle specification after service
Internal module fault due to moisture or component failure

Fault status

⚠️ Status

U0484 - Invalid data received from Rear Lighting Control Module B (communication/data integrity error)

🟡 Repair difficulty: Medium

⏱️ Diagnostic time: 1.0-3.0 hours

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U0484 — Invalid data received from the rear lighting control module B invalid