U0046

Code

LAND ROVER U — Network/User

Vehicle Communication Bus C

Brand: LAND ROVER

Type: U — Network/User

Views: UK: 15 EN: 39 RU: 26

AI status

Completed

ready

Completed 100%

Page language: EN

Causes

Open, short to ground, or short to battery in CAN Bus C wiring
Failed or intermittent module (ECU) on Bus C
Missing or failed CAN bus termination resistor(s)
Corroded, loose or damaged connectors at a module or splice
Low battery voltage or poor battery/ground connections
Aftermarket device or accessory improperly connected to the bus

Symptoms

Multiple U-codes and/or MIL illuminated
Specific features or systems on Bus C unavailable (e.g., ABS, stability control, instrument cluster, gateway functions)
Scanner shows no response or intermittent responses from one or more modules on Bus C
Random or permanent loss of message data, incorrect instrument readouts
Vehicle may enter limp mode or disable dependent systems

What to check

Read and record all stored and pending codes from all modules (note module addressing)
Visually inspect wiring, connectors and splices for damage, corrosion, water ingress, bent pins or loose connectors
Check battery voltage and charging system; ensure strong battery and clean ground connections
Check for aftermarket modules/devices tied into vehicle networks and disconnect if present
Confirm vehicle service history and Technical Service Bulletins (TSBs) for known Bus C issues or software updates

Signal parameters

CAN bus idle differential voltage: ~0 V differential with CAN_H ≈2.5 V and CAN_L ≈2.5 V (recessive)
CAN dominant state: CAN_H ≈3.5 V, CAN_L ≈1.5 V (approximate values)
Two 120 Ω terminators present → measured end-to-end ≈60 Ω across differential
Oscilloscope expected: clean square-ish differential CAN waveform at vehicle data rate (commonly 500 kb/s or 250 kb/s depending on vehicle)

Diagnostic algorithm

Connect a professional-level scan tool and download U0046 plus all communication-related codes from every module; note which modules report loss of Bus C
Confirm battery voltage >12.4 V (engine off) and good charging system; ensure solid battery negative to chassis and engine ground connections
Perform visual inspection of Bus C wiring harness from modules that are on that bus; check connectors for corrosion, bent pins, or water damage
With ignition on, measure DC resistance across CAN_H to CAN_L at two points (end points) — expected approximately 60 Ω; if open or very high resistance, suspect open or missing terminator(s)
Use a digital multimeter to check for shorts to ground or battery on CAN_H and CAN_L (voltage presence when others disconnected)
If resistance and voltages look normal, use an oscilloscope (or CAN diagnostic tool) at a module connector to view CAN_H and CAN_L waveforms; look for noise, missing frames, stuck dominant or recessive states, or low amplitude
If a single module is suspected, disconnect modules on Bus C one at a time (with vehicle power as required by manufacturer) to see if fault clears — this can isolate a faulty node that is pulling the bus down
Inspect and repair any damaged wiring or connectors found; clean and re-pin as required using OEM procedures
After repair or isolation, clear codes and verify communication is restored and no other modules report fault codes; if communication is intermittent, inspect for intermittent wiring faults (move harness while monitoring)
If wiring and connectors check good and a specific module is non-responsive, follow OEM procedures for module reprogramming or replacement; check for software updates and reflash as required

Likely causes

Broken/shorted CAN wiring or connector on Bus C
Failed module attached to Bus C
Missing or faulty terminator resistor(s)
Battery/ground issue causing communication loss

Fault status

⚠️ Status

Communication fault detected on Vehicle Communication Bus C — one or more modules not communicating or invalid messages received.

🔴 Repair difficulty: Hard

⏱️ Diagnostic time: 2.0-5.0 hours

Similar codes

Repair manuals

Manual library for LAND ROVER

413

Browse 413 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