U2604

Code

LAND ROVER U — Network/User

Lost Communication with Transfer Case Control Module

Brand: LAND ROVER

Type: U — Network/User

Views: UK: 34 EN: 62 RU: 37

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Page language: EN

Causes

Faulty Transfer Case Control Module (TCCM)
Open or shorted CAN/LIN bus wiring between TCCM and network
Poor power supply or ground to the TCCM (blown fuse, corroded ground)
Corroded or damaged connector at TCCM
Termination resistor open or shorted on CAN bus
Software/firmware mismatch or module requiring reflash

Symptoms

Transfer case warning light or 4x4 system warning message
Inability to shift between 2WD/4WD modes or transfer case stuck
Reduced traction / limp-home mode or limited drive modes
Other modules report CAN bus communication errors
Intermittent or permanent loss of features related to transfer case

What to check

Use a diagnostic scan tool to read and record all U-codes and freeze frame data
Verify battery voltage is within normal range (12.4–12.8 V at rest; 13.5–14.8 V while running)
Inspect TCCM connector and harness for corrosion, pin damage, water ingress or chafing
Verify fuses and ignition power feeds to the TCCM
Check network status on scan tool for module presence and bus errors
Measure CAN High/Low voltages at the TCCM connector with ignition on

Signal parameters

CAN High (idle): ~2.5 V (recessive), CAN Low (idle): ~2.5 V; dominant state: CANH ~3.5 V, CANL ~1.5 V
Differential voltage when idle: near 0 V; dominant differential ~2.0 V
Bus termination: ~60 ohms across CAN H and CAN L (two 120 ohm terminators in parallel)
Expected: TCCM should appear on network and respond to CAN messages (module ID present in scan tool)
No excessive bus error counters or repeated bus-off status reported

Diagnostic algorithm

Connect a scan tool and document U2604 plus any related codes and freeze data. Note module presence on network.
Check battery voltage and charge if necessary. Repeat communication test.
Visually inspect TCCM connector, pins and harness for damage, corrosion, water, or rodent damage. Repair as needed.
Verify power and ground at the TCCM connector with ignition ON. Check relevant fuses and relays. Repair any open circuits.
With ignition ON, measure CAN H/L voltages at the TCCM connector. Compare to expected values. If abnormal, isolate wiring to find short/open.
Measure resistance across CAN H and CAN L with ignition OFF — it should be approximately 60 ohms. If not, inspect termination resistors and wiring to other modules.
If voltages and termination are correct, attempt to communicate with the TCCM via the scan tool. If module is not present, perform a wiggle test of connectors/harness while monitoring communication.
If a short to battery or ground is suspected, isolate segments of the bus (disconnect other modules or remove connectors) to locate the fault.
If harness and network are good but the TCCM does not respond, consider reflashing/reprogramming the module per manufacturer procedures. Check for required software updates or calibration.
Replace TCCM only after confirming the module is defective and that wiring, power, ground, and bus termination are correct. After replacement, program/configure the new module and clear codes, then verify system operation.

Likely causes

Disconnected or corroded connector at the TCCM
CAN high/low short to power or ground near TCCM
Failed TCCM hardware or internal controller fault
Blown fuse or poor battery/ignition supply to module

Fault status

⚠️ Status

Lost communication with Transfer Case Control Module (network fault)

🟡 Repair difficulty: Medium

⏱️ Diagnostic time: 1.0-3.0 hours

Repair manuals

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