U1222

Code

LAND ROVER U — Network/User

SCP (J1850) invalid or missing data for interior lights

Brand: LAND ROVER

Type: U — Network/User

Views: UK: 31 EN: 65 RU: 28

AI status

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Page language: EN

Causes

Open or short in SCP/J1850 wiring or connectors
Faulty interior lights module or body control module (BCM)
Low or unstable battery/vehicle voltage affecting communications
Corroded or intermittent connector at a module on the SCP network
Software/firmware mismatch or module not configured correctly
Damaged or noisy SCP bus (interference, short to supply or ground)

Symptoms

Dome/courtesy lights inoperative or intermittent
Interior lights behave erratically (stay on, do not dim, or do not respond to door switches)
Other modules on the SCP network may show communication faults or unexpected behavior
Relevant lamp or BCM-related functions fail or are disabled
Potential battery drain if lights remain on unexpectedly

What to check

Retrieve freeze frame and handshake data from all modules on the SCP/J1850 network with a capable scan tool
Check vehicle battery voltage and charging system for stable supply (with engine off and running)
Visually inspect connectors and wiring related to the BCM and interior lights module for corrosion, damage, or loose pins
Check for aftermarket accessories spliced into interior light circuits or network wiring
Monitor the SCP data stream (CAN-equivalent network trace) to confirm presence and quality of interior light messages

Signal parameters

Presence of periodic SCP interior-lights messages from the lighting module (message ID/name dependent on vehicle)
Message frequency: expected periodic transmission vs. request-response behavior (should be consistent with other modules)
Message contents: valid data bytes for interior lamp status and checksum/CRC if used
Bus voltage level on SCP line when idle and during transmission (stable, no excessive transients)

Diagnostic algorithm

Confirm the code: clear DTCs and recheck if U1222 returns; note if fault is permanent or intermittent.
Check battery and charging system voltage; ensure battery state is >12.4V during tests to avoid false comm errors.
Using a scan tool, view live data from the BCM and any interior light module; verify whether expected interior-light messages are present and valid.
Inspect connectors and wiring at the BCM and interior lighting module(s) for corrosion, bent pins, or damage. Wiggle test harnesses while monitoring live data for intermittent faults.
If messages are missing or corrupted, isolate by disconnecting nonessential modules on the same SCP bus one at a time (when safe) to see if communication resumes, or swap suspected module with known-good unit if available.
Check for recent repairs or aftermarket installations that may have disturbed the SCP wiring; remove or correct any splices or adapters.
If wiring and connectors are good but messages remain invalid, perform further module-level testing: reflashing or updating module software per manufacturer service information, or reprogramming as required.
Replace the faulty module only after confirming the module itself is the source of invalid data and wiring has been verified.
After repair, clear DTCs and verify normal operation and that U1222 does not return under normal conditions.

Likely causes

Damaged or loose connector at the interior lights lamp module or BCM
Faulty BCM or interior lighting module failing to transmit proper SCP messages
Aftermarket accessory or poor repair disturbed the SCP wiring harness
Battery recently disconnected or replaced and modules require reprogramming

Fault status

⚠️ Status

Stored when the BCM detects invalid or missing SCP/J1850 data related to interior lighting; may be intermittent or active depending on occurrence.

🟡 Repair difficulty: Medium

⏱️ Diagnostic time: 1.0-2.5 hours

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