U0242

Code

LAND ROVER U — Network/User

Lost communication with headlight control module B

Brand: LAND ROVER

Type: U — Network/User

Views: UK: 16 EN: 47 RU: 18

AI status

Completed

ready

Completed 100%

Page language: EN

Causes

Faulty headlight control module B
Open/short or intermittent wiring between module and CAN bus or power/ground
Corroded or damaged connector pins at the headlight module
Blown fuse or missing module supply voltage
CAN bus termination or wiring fault (short to ground/power)
Module software/firmware fault or incomplete programming

Symptoms

Headlights reduced functionality (inoperative low/high beam, adaptive features disabled)
Dashboard message or warning lamp indicating headlight fault or network fault
Other lighting-related systems may default to limp mode
Related modules report communication faults or multiple U-codes
Interior message: 'Service Lighting' or similar

What to check

Connect a diagnostic scan tool to confirm U0242 and read related U-codes and freeze frame data
Check battery voltage (stable, >12V) and inspect fuses/relays for headlight/module circuits
Visually inspect headlight control module connector and wiring for corrosion, damage, or water ingress
Probe module connector for key voltages: 12V supply, ground continuity
Measure CAN bus voltages at the headlight module pins (CAN_H, CAN_L) and compare to expected values
Measure termination resistance between CAN_H and CAN_L (approx. 60 ohms with two 120Ω terminators)

Signal parameters

Module supply voltage: approx. 11–14 V with ignition on
Ground continuity: near 0 Ω to chassis ground
CAN bus idle voltages: CAN_H ≈ 2.5 V, CAN_L ≈ 2.5 V (recessive)
CAN dominant state: CAN_H ≈ 3.5 V, CAN_L ≈ 1.5 V during activity
Termination resistance (CAN_H to CAN_L): ≈ 60 Ω (two 120 Ω terminators in parallel)
Expected CAN activity: continuous message traffic on high-speed CAN when ignition on (confirm with scope/scan tool)

Diagnostic algorithm

Retrieve all stored and pending codes with a scan tool; note freeze frame and any related U-codes.
Confirm whether headlight control module B appears on the vehicle network (module present list).
Check battery voltage and relevant fuses/relays; replace/repair if faulty.
Visually inspect the headlight control module connector and wiring harness for damage, corrosion, or water entry; repair as needed.
With ignition on, measure module supply and ground at the module connector. Repair wiring or ground issues if out of range.
Measure CAN_H and CAN_L at the module connector and at other nodes/gateway. Compare voltages and check for expected differential activity with an oscilloscope if available.
Check termination resistance across CAN_H and CAN_L (~60 Ω). Locate and repair any short to battery or ground if termination is wrong.
If wiring and bus integrity are confirmed, attempt a module wake/reset following manufacturer procedure (power cycle; clear codes).
If module still does not communicate, consult service information for module reprogramming or reflashing. Reprogram only with proper tools and procedures.
If a module swap is required, confirm replacement unit is programmed/configured for the vehicle. After repair, clear codes and verify system operation and that the code does not return.

Likely causes

Bad connector or pin corrosion at headlight control module
Low battery or blown fuse feeding the headlight module
CAN bus short or broken wire near the headlight module
Failed headlight control module
Intermittent wiring due to chafing or water ingress

Fault status

⚠️ Status

Lost communication with Headlight Control Module B — no response on CAN bus

🟡 Repair difficulty: Medium

⏱️ Diagnostic time: 1.0-3.0 hours

Similar codes

Repair manuals

Manual library for LAND ROVER

320

Browse 320 LAND ROVER manuals: repair procedures, diagnostics, wiring diagrams, component locations, service data and Labor Times by year, model and trim.

LAND ROVER

Your experience will help others

+100 karma for a short comment :)

Was this AI description helpful?

Your feedback helps improve AI descriptions.

👍 Like 0 👎 Dislike 0

Send to email

U0242 — Lost communication with headlight control module B