Code
U1262
LAND ROVER
U — Network/User
SCP (J1850) Communication bus failure
Views:
UK: 5
EN: 11
RU: 7
AI status
Completed
Completed
100%
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
Similar codes
Workshop Manuals
Repair manuals for LAND ROVER
3
Land Rover Defender 300Tdi — Workshop Manual (1996 model year)
Workshop Manual199,00 UAH
Land Rover Defender Workshop Manual Supplement & Body Repair Manual (1999 & 2002 MY)
Workshop Manual199,00 UAH
Land Rover Range Rover — Electrical Library (LRL 0453ENG, 2002)
Workshop Manual199,00 UAH
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Code
U1262
Other
U — Network/User
SCP (J1850) Communication Bus Fault
Views:
UK: 17
EN: 37
RU: 27
AI status
Completed
Completed
100%
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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LAND ROVER 3
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