U0005

Code

LAND ROVER U — Network/User

High-speed CAN communication bus (+) high

Brand: LAND ROVER

Type: U — Network/User

Views: UK: 41 EN: 51 RU: 44

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Page language: EN

Causes

Short circuit of CAN_H to battery voltage (12 V)
Faulty CAN transceiver or control module driving CAN_H high
Damaged wiring or chafed insulation contacting power
Corroded or loose connector pins causing improper voltage levels
Incorrect or missing termination (open/shorted resistor)
Aftermarket device or module connected to the CAN bus causing a fault

Symptoms

Multiple control modules show communication faults or are not detected
CAN-related DTCs present (communication/network errors)
Intermittent or permanent loss of functions controlled over the bus (e.g., engine, ABS, cluster, infotainment)
Erratic instrument cluster readings or warning lights
Vehicle may not start or go into limp mode if critical modules lose communication

What to check

Read and record all stored and pending U- and P-codes and freeze-frame data from all modules.
Visually inspect CAN_H and CAN_L wiring, terminals and connectors for damage, corrosion or intrusion by other wiring.
Check battery voltage and main grounds; ensure stable supply before testing bus voltages.
Measure DC voltage of CAN_H and CAN_L relative to chassis ground with key ON, engine OFF (expected idle about 2.5 V each).
Measure resistance across CAN_H to CAN_L with the bus disconnected and ignition off; expected ≈ 60 ohms (two 120 Ω terminators in parallel).
Probe CAN_H and CAN_L with an oscilloscope while exercising network traffic to view waveform and identify a driver stuck dominant/high.

Signal parameters

Idle (recessive) voltage: CAN_H ≈ 2.5 V (typical range ~2.0–3.0 V), CAN_L ≈ 2.5 V
Dominant state: CAN_H ≈ 3.5 V, CAN_L ≈ 1.5 V (differential ≈ 2.0 V)
Termination resistance (bus end-to-end with ignition off): ≈ 60 Ω (two 120 Ω in parallel)
High-speed CAN bit rate (typical): 500 kbps (model-dependent; some systems use 250 kbps)

Diagnostic algorithm

Record all active and pending codes from all modules and note which modules report loss of communication.
Perform a visual inspection of CAN wiring, connectors, and module grounds for obvious damage or corrosion.
Verify battery voltage and main chassis/engine ground connections are clean and tight.
With ignition ON (engine OFF), measure CAN_H and CAN_L voltages at a convenient connector pin; compare to expected idle values (~2.5 V).
Measure resistance between CAN_H and CAN_L with ignition OFF; verify ≈ 60 Ω. If open or very low, suspect missing terminators or short.
If CAN_H is high, isolate by disconnecting connectors or unplugging modules (start with non-critical/accessible modules) one at a time while monitoring CAN_H to see if voltage returns to normal.
Use an oscilloscope to examine bus waveforms to identify a node driving the bus high or excessive noise. Look for a stuck dominant state on CAN_H.
Inspect and repair damaged wiring or replace corroded connectors. Replace the module if its transceiver is identified as the cause.
After repairs, clear codes, cycle ignition and run the vehicle to verify bus voltages and that all modules communicate normally.
If intermittent, perform extended road test and logging, and consider replacement of harness sections or modules causing the intermittent event.

Likely causes

Short to battery on CAN_H wiring (most common)
Failed transceiver in one control module forcing CAN_H high
Damaged connector or pin contamination at a module on the high-speed CAN
Missing/failed termination resistor causing abnormal voltages

Fault status

⚠️ Status

High-speed CAN bus: CAN_H voltage above allowed threshold. Communication errors detected on the high-speed CAN network.

🟡 Repair difficulty: Medium

⏱️ Diagnostic time: 1.0-3.0 hours

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U0005 — High-speed CAN communication bus (+) high