U2516

Code

LAND ROVER U — Network/User

U2516 — Loss of communication with rear electronic module

Brand: LAND ROVER

Type: U — Network/User

Views: UK: 26 EN: 38 RU: 34

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Page language: EN

Causes

Open, shorted or noisy CAN bus wiring between REM and network
Loss of power or ground to the REM (blown fuse, poor ground, battery issues)
Corroded or damaged REM connector or pins (water ingress)
REM internal electronic failure or firmware fault
Faulty gateway/central module or other module pulling the CAN bus down
Incorrect or interrupted module programming or software update

Symptoms

Rear lights, tailgate release, rear wiper, parking sensors or rear door functions inoperative
Instrument cluster or message center displays communication/fault warnings
One or more related systems show fault codes or disabled status
Intermittent loss of rear functions that may return after ignition cycle
Possible multiple U-code entries referencing rear module or CAN network

What to check

Connect a diagnostic scan tool and confirm U2516 plus any related stored or pending U/C codes
Verify battery voltage (>=12.4 V) and inspect battery terminals for corrosion
Check fuses/relays supplying the REM and replace if blown
Visually inspect REM connector and wiring for corrosion, bent pins, water damage or physical damage
Check for presence of the REM on the vehicle network (scan tool node list / module finder)
Use scan tool to view CAN bus error counters and bus activity/status

Signal parameters

CAN_H idle ≈ 2.5 V, CAN_L idle ≈ 2.5 V (recessive). During dominant bits CAN_H ≈ 3.5 V, CAN_L ≈ 1.5 V
Differential CAN voltage during activity ≈ 2.0 V (dominant) vs ≈ 0 V (recessive)
Termination: two 120 Ω resistors in parallel ≈ 60 Ω across CAN_H–CAN_L
Expected module responses: REM should appear on network node list and publish periodic messages (message frequency varies by vehicle)
Observe CAN error counters and bus load with a scope or advanced scan tool for noise or collisions

Diagnostic algorithm

Capture freeze frame and full list of stored codes; note any other U-codes or B/C codes that may point to related issues.
Confirm inability to communicate with the REM using a dealer-level or capable OEM scan tool. Attempt to read module ID where supported.
Check battery voltage and main fuses/relays that feed the REM. Replace any blown fuses and retest communication.
Visually inspect the REM and harness for corrosion, water entry, crushed/abraded wiring and connector pin damage. Repair as required.
Verify power and ground at the REM connector pins with ignition on. Repair any poor connections before proceeding.
With ignition on, measure CAN_H and CAN_L at the REM connector: verify idle voltages (~2.5 V), differential and check for short to power/ground.
Measure termination resistance across CAN_H and CAN_L (~60 Ω). If open or far from spec, trace wiring to find missing terminator or open circuit.
Use an oscilloscope (preferred) or advanced CAN tester to view waveform quality and activity. Look for excessive noise, voltage spikes or missing frames.
Disconnect the REM and inspect connector terminals for corrosion; test continuity of CAN lines back to the nearest gateway/module. Isolate to find short/open.
If wiring and power/grounds are good, attempt to re-establish communication after clearing codes. If module remains non-responsive, consider module swap with a known-good REM (if available) or replacement following OEM pairing/programming procedures.
If module replacement required, follow manufacturer procedures for coding/calibration, and check for any required software updates or TSBs. Recheck all affected systems and clear codes.
Document findings and repair actions. If intermittent or complex network issues persist, consult manufacturer technical support or wiring diagrams for backbone tracing.

Likely causes

Poor power/ground or blown fuse to the REM
Damaged or corroded REM connector at the rear of the vehicle
CAN_H or CAN_L shorted to battery, ground, or each other
Open/poor continuity in CAN wiring harness (pins broken or chafed)
REM hardware failure or module software mismatch
Intermittent fault caused by water intrusion into rear module area

Fault status

⚠️ Status

Loss of communication with Rear Electronic Module (REM) — no valid CAN responses from the REM detected by the network.

🟡 Repair difficulty: Medium

⏱️ Diagnostic time: 1.5 - 4.0 hours

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