Code
U0252
Generic
U — Network/User
Lost Communication With Lighting Control Module - Rear B
Views:
UK: 26
EN: 63
RU: 18
AI status
Completed
Completed
100%
Causes
- Failed or unpowered rear lighting control module
- Open, shorted, or high-resistance wiring in the CAN/data-bus between the module and other controllers
- Corroded, loose or damaged connectors or pins at the module or junctions
- Blown fuse or lost ignition-switched/constant power or ground to the module
- Network termination or wiring harness damage (short to battery, ground, or another signal)
- Faulty gateway/BCM/other module that routes CAN messages
Symptoms
- Rear exterior lights (stop/taillights/turn signals) partially or completely inoperative
- Driver information/warning message about rear lights or network communication
- Other modules report loss of communication with the Rear Lighting Control Module
- CAN bus related errors or multiple U-codes present
- Intermittent operation of rear lighting functions (flicker, delayed response)
What to check
- Connect a scan tool and confirm U0252 and any other network codes; note any freeze-frame or network status data
- Check battery and charging voltage (should be ~12.4–14.6 V) before starting diagnostics
- Inspect fuses/relays powering the rear lighting control module and any related junction blocks
- Visually inspect connectors and wiring for corrosion, damage, or signs of moisture at the rear lighting module and intermediate junctions
- Check for other U-codes that indicate gateway/BCM or CAN bus faults
- With ignition on, verify module is present on the network with a capable scan tool (module list or CAN alive status)
Signal parameters
- CAN bus idle voltages (approx.): CAN_H ~2.5 V, CAN_L ~2.5 V (recessive)
- Dominant state: CAN_H ~3.5 V, CAN_L ~1.5 V (typical differential ≈2.0 V)
- Expected bus termination: combined ~60 ohms between CAN_H and CAN_L with ignition on (two 120 ohm terminators)
- Typical data rates: 250 kb/s or 500 kb/s depending on vehicle (confirm from wiring diagram)
- Supply voltage to module: battery/ignition feed ~12 V (range ~9–16 V when running)
- Module ground resistance to chassis: should be low (
Diagnostic algorithm
- Read all stored DTCs and freeze-frame data with a full-feature scan tool; record any related U-codes
- Verify battery voltage and ensure stable power; recharge if low and repeat scan to clear intermittent codes
- Locate rear lighting control module and its power/ground fuses/relays using wiring diagrams; check fuses and relays for continuity and correct operation
- Visually inspect connectors at the rear lighting module and intermediate splice/junction points for corrosion, bent pins, or loose terminals; disconnect and reseat connectors
- With ignition ON (engine off), use a multimeter to check for module supply voltage at the power pin(s) and solid chassis ground at the ground pin(s). Repair any open circuits
- Check CAN bus presence at the module: measure CAN_H and CAN_L voltages with key on; look for proper idle voltages and differential when exercising signals (activate turn signals/hazards)
- If the bus appears dead at the module but active elsewhere, trace wiring between the module and the nearest network node/junction; perform continuity and short-to-power/ground tests on CAN_H and CAN_L
- Wiggle-test wiring and connectors while monitoring bus activity to reproduce intermittent faults
- Measure termination resistance between CAN_H and CAN_L with power off; confirm ~60 ohms or per vehicle specification
- If wiring and power/ground are good and bus messages are present but the module does not respond, attempt module wake/initialization via scan tool; reprogram or update module software if update is available and indicated
- If available, swap with a known-good identical module (or substitute known working node) to confirm module failure—only after verifying VIN-specific programming requirements
- After repairs or replacement, clear DTCs and verify correct operation of rear lighting and that code does not return; perform final road test and re-scan
Likely causes
- Module has no battery/ignition power or bad ground at the rear lighting control module
- Broken or corroded connector or wiring harness near the rear lamp module or chassis junctions
- CAN High/Low shorted to each other or to supply/ground on the segment feeding the rear lighting module
- Faulty rear lighting control module
- Faulty gateway or bus driver in a controller upstream of the module
Fault status
Status
Controller reports loss of communication with the Rear Lighting Control Module. The network controller did not receive expected messages or responses from that module, so the ECU logged U0252 and may set related indicators or disable rear lighting functions.
Repair difficulty: Medium
Diagnostic time: 1-3 hours
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Code
U0252
HYUNDAI
U — Network/User
Lost Communication With Lighting Control Module Rear “B”
Views:
UK: 12
EN: 21
RU: 12
AI status
Completed
Completed
100%
Causes
- Failed or unpowered rear lighting control module
- Open, shorted, or high-resistance wiring in the CAN/data-bus between the module and other controllers
- Corroded, loose or damaged connectors or pins at the module or junctions
- Blown fuse or lost ignition-switched/constant power or ground to the module
- Network termination or wiring harness damage (short to battery, ground, or another signal)
- Faulty gateway/BCM/other module that routes CAN messages
Symptoms
- Rear exterior lights (stop/taillights/turn signals) partially or completely inoperative
- Driver information/warning message about rear lights or network communication
- Other modules report loss of communication with the Rear Lighting Control Module
- CAN bus related errors or multiple U-codes present
- Intermittent operation of rear lighting functions (flicker, delayed response)
What to check
- Connect a scan tool and confirm U0252 and any other network codes; note any freeze-frame or network status data
- Check battery and charging voltage (should be ~12.4–14.6 V) before starting diagnostics
- Inspect fuses/relays powering the rear lighting control module and any related junction blocks
- Visually inspect connectors and wiring for corrosion, damage, or signs of moisture at the rear lighting module and intermediate junctions
- Check for other U-codes that indicate gateway/BCM or CAN bus faults
- With ignition on, verify module is present on the network with a capable scan tool (module list or CAN alive status)
Signal parameters
- CAN bus idle voltages (approx.): CAN_H ~2.5 V, CAN_L ~2.5 V (recessive)
- Dominant state: CAN_H ~3.5 V, CAN_L ~1.5 V (typical differential ≈2.0 V)
- Expected bus termination: combined ~60 ohms between CAN_H and CAN_L with ignition on (two 120 ohm terminators)
- Typical data rates: 250 kb/s or 500 kb/s depending on vehicle (confirm from wiring diagram)
- Supply voltage to module: battery/ignition feed ~12 V (range ~9–16 V when running)
- Module ground resistance to chassis: should be low (
Diagnostic algorithm
- Read all stored DTCs and freeze-frame data with a full-feature scan tool; record any related U-codes
- Verify battery voltage and ensure stable power; recharge if low and repeat scan to clear intermittent codes
- Locate rear lighting control module and its power/ground fuses/relays using wiring diagrams; check fuses and relays for continuity and correct operation
- Visually inspect connectors at the rear lighting module and intermediate splice/junction points for corrosion, bent pins, or loose terminals; disconnect and reseat connectors
- With ignition ON (engine off), use a multimeter to check for module supply voltage at the power pin(s) and solid chassis ground at the ground pin(s). Repair any open circuits
- Check CAN bus presence at the module: measure CAN_H and CAN_L voltages with key on; look for proper idle voltages and differential when exercising signals (activate turn signals/hazards)
- If the bus appears dead at the module but active elsewhere, trace wiring between the module and the nearest network node/junction; perform continuity and short-to-power/ground tests on CAN_H and CAN_L
- Wiggle-test wiring and connectors while monitoring bus activity to reproduce intermittent faults
- Measure termination resistance between CAN_H and CAN_L with power off; confirm ~60 ohms or per vehicle specification
- If wiring and power/ground are good and bus messages are present but the module does not respond, attempt module wake/initialization via scan tool; reprogram or update module software if update is available and indicated
- If available, swap with a known-good identical module (or substitute known working node) to confirm module failure—only after verifying VIN-specific programming requirements
- After repairs or replacement, clear DTCs and verify correct operation of rear lighting and that code does not return; perform final road test and re-scan
Likely causes
- Module has no battery/ignition power or bad ground at the rear lighting control module
- Broken or corroded connector or wiring harness near the rear lamp module or chassis junctions
- CAN High/Low shorted to each other or to supply/ground on the segment feeding the rear lighting module
- Faulty rear lighting control module
- Faulty gateway or bus driver in a controller upstream of the module
Fault status
Status
Controller reports loss of communication with the Rear Lighting Control Module. The network controller did not receive expected messages or responses from that module, so the ECU logged U0252 and may set related indicators or disable rear lighting functions.
Repair difficulty: Medium
Diagnostic time: 1-3 hours
Similar codes
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Code
U0252
LAND ROVER
U — Network/User
Lost communication with the rear lighting control module B
Views:
UK: 6
EN: 17
RU: 5
AI status
Completed
Completed
100%
Causes
- Failed or unpowered rear lighting control module
- Open, shorted, or high-resistance wiring in the CAN/data-bus between the module and other controllers
- Corroded, loose or damaged connectors or pins at the module or junctions
- Blown fuse or lost ignition-switched/constant power or ground to the module
- Network termination or wiring harness damage (short to battery, ground, or another signal)
- Faulty gateway/BCM/other module that routes CAN messages
Symptoms
- Rear exterior lights (stop/taillights/turn signals) partially or completely inoperative
- Driver information/warning message about rear lights or network communication
- Other modules report loss of communication with the Rear Lighting Control Module
- CAN bus related errors or multiple U-codes present
- Intermittent operation of rear lighting functions (flicker, delayed response)
What to check
- Connect a scan tool and confirm U0252 and any other network codes; note any freeze-frame or network status data
- Check battery and charging voltage (should be ~12.4–14.6 V) before starting diagnostics
- Inspect fuses/relays powering the rear lighting control module and any related junction blocks
- Visually inspect connectors and wiring for corrosion, damage, or signs of moisture at the rear lighting module and intermediate junctions
- Check for other U-codes that indicate gateway/BCM or CAN bus faults
- With ignition on, verify module is present on the network with a capable scan tool (module list or CAN alive status)
Signal parameters
- CAN bus idle voltages (approx.): CAN_H ~2.5 V, CAN_L ~2.5 V (recessive)
- Dominant state: CAN_H ~3.5 V, CAN_L ~1.5 V (typical differential ≈2.0 V)
- Expected bus termination: combined ~60 ohms between CAN_H and CAN_L with ignition on (two 120 ohm terminators)
- Typical data rates: 250 kb/s or 500 kb/s depending on vehicle (confirm from wiring diagram)
- Supply voltage to module: battery/ignition feed ~12 V (range ~9–16 V when running)
- Module ground resistance to chassis: should be low (
Diagnostic algorithm
- Read all stored DTCs and freeze-frame data with a full-feature scan tool; record any related U-codes
- Verify battery voltage and ensure stable power; recharge if low and repeat scan to clear intermittent codes
- Locate rear lighting control module and its power/ground fuses/relays using wiring diagrams; check fuses and relays for continuity and correct operation
- Visually inspect connectors at the rear lighting module and intermediate splice/junction points for corrosion, bent pins, or loose terminals; disconnect and reseat connectors
- With ignition ON (engine off), use a multimeter to check for module supply voltage at the power pin(s) and solid chassis ground at the ground pin(s). Repair any open circuits
- Check CAN bus presence at the module: measure CAN_H and CAN_L voltages with key on; look for proper idle voltages and differential when exercising signals (activate turn signals/hazards)
- If the bus appears dead at the module but active elsewhere, trace wiring between the module and the nearest network node/junction; perform continuity and short-to-power/ground tests on CAN_H and CAN_L
- Wiggle-test wiring and connectors while monitoring bus activity to reproduce intermittent faults
- Measure termination resistance between CAN_H and CAN_L with power off; confirm ~60 ohms or per vehicle specification
- If wiring and power/ground are good and bus messages are present but the module does not respond, attempt module wake/initialization via scan tool; reprogram or update module software if update is available and indicated
- If available, swap with a known-good identical module (or substitute known working node) to confirm module failure—only after verifying VIN-specific programming requirements
- After repairs or replacement, clear DTCs and verify correct operation of rear lighting and that code does not return; perform final road test and re-scan
Likely causes
- Module has no battery/ignition power or bad ground at the rear lighting control module
- Broken or corroded connector or wiring harness near the rear lamp module or chassis junctions
- CAN High/Low shorted to each other or to supply/ground on the segment feeding the rear lighting module
- Faulty rear lighting control module
- Faulty gateway or bus driver in a controller upstream of the module
Fault status
Status
Controller reports loss of communication with the Rear Lighting Control Module. The network controller did not receive expected messages or responses from that module, so the ECU logged U0252 and may set related indicators or disable rear lighting functions.
Repair difficulty: Medium
Diagnostic time: 1-3 hours
Similar codes
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Repair manuals for LAND ROVER
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Land Rover Defender 300Tdi — Workshop Manual (1996 model year)
Workshop Manual199,00 UAH
Land Rover Defender Workshop Manual Supplement & Body Repair Manual (1999 & 2002 MY)
Workshop Manual199,00 UAH
Land Rover Range Rover — Electrical Library (LRL 0453ENG, 2002)
Workshop Manual199,00 UAH
Your experience will help others
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Was this AI description helpful?
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