U1262

Code

LAND ROVER U — Network/User

SCP (J1850) Communication bus failure

Brand: LAND ROVER

Type: U — Network/User

Views: UK: 17 EN: 38 RU: 21

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Page language: EN

Causes

Open, short, or intermittent wiring on the SCP (J1850) bus
Corroded or loose connectors at modules or splice points
Failed control module (ECM/BCM/other) pulling the bus down
Missing or incorrect termination or bus resistors
Low battery voltage, poor battery connections or weak charging system
Blown fuse supplying power to one or more bus modules

Symptoms

MIL illuminated and U1262 stored in memory
Loss of communication with one or more modules (e.g., BCM, ABS, instrument cluster)
Multiple unrelated warnings or features not working (locks, lights, HVAC, instrumentation)
Scan tool unable to connect to some modules or shows 'bus off' or timeout errors
Intermittent faults that change with vibration or connector manipulation

What to check

Check and record battery voltage and charging system health
Inspect fuses and fusible links related to the affected modules
Visually inspect SCP/J1850 wiring, connectors, and ground points for corrosion, damage, or loose pins
Use a scan tool to read module presence and communication status across the network
Wiggle connectors and harnesses while monitoring bus communication for intermittent changes
Disconnect aftermarket devices that connect to vehicle wiring and re-check

Signal parameters

SCP/J1850 is a vehicle serial communication bus; traffic appears as digital pulse trains when active
Idle bus state is typically a defined voltage level and active communication is visible as periodic voltage transitions (use oscilloscope to view)
Expected behavior: multiple modules respond to scan tool queries; no module should continuously hold the bus dominant
If the bus is shorted to power or ground the waveform will be absent or held at a static voltage
Refer to Land Rover factory documentation for exact waveform timing, voltage thresholds and termination requirements

Diagnostic algorithm

Retrieve freeze frame and full DTC list with a diagnostic scanner; note any other communication codes.
Verify battery voltage (12.4–12.8 V resting) and inspect battery terminals and main grounds; charge or repair as needed.
Inspect all fuses and power feeds for modules on the SCP bus; replace any blown fuses and re-test.
Visually inspect connectors, splice points and harness routing for physical damage, corrosion or water ingress; repair or secure as required.
With scanner connected, identify which modules are not responding. Attempt to communicate with each module individually.
Perform wiggle/pressure tests at suspect connectors while monitoring bus communication and stored codes to find intermittent faults.
Measure power and ground at non-communicating modules; verify they have proper supply and ground continuity.
If basic checks pass, use an oscilloscope to probe the bus at multiple locations. Look for expected pulse activity and compare waveforms between locations to isolate area of failure.
Isolate and disconnect suspect module(s) one at a time and observe if bus communication is restored to identify a module loading the bus.
If a faulty module is identified, verify with manufacturer procedures (reprogram/replace only after isolating as root cause).
After repairs, clear codes, perform a full system scan and road test to confirm the fault does not return. Update module software if recommended by manufacturer.

Likely causes

Damaged or disconnected wiring harness on J1850/SCP circuit
Corroded connector at a commonly affected module (BCM, IPC, ECM)
Single failed module loading or shorting the bus
Loose battery or poor ground affecting communication
Recent repair or aftermarket installation disturbed the bus wiring

Fault status

⚠️ Status

SCP (J1850) Communication bus failure — loss of communication on the SCP/J1850 network

🟡 Repair difficulty: Medium

⏱️ Diagnostic time: 1.0-3.0 hours

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