Code
U1400
Generic
U — Network/User
Invalid Data Received From Control Module
AI status
Completed
Completed
100%
Causes
- Faulty or intermittent wiring/connectors on vehicle data bus
- Failed control module (sender or receiver)
- Network voltage problems (low battery, poor ground)
- Missing or incorrect termination/resistors on bus
- Software mismatch or corrupted module software
- Electromagnetic interference or short to chassis
Symptoms
- Illumination of MIL or communication-related warning lights
- Loss of function of one or more control systems (e.g., ABS, transmission, body controls)
- Intermittent or persistent fault codes stored from multiple modules
- Unresponsive modules or delayed responses to inputs
- Multiple modules reporting communication errors
What to check
- Scan all modules with a professional diagnostic tool; record freeze frame and U-codes
- Check battery voltage (static and cranking) and main ground connections
- Inspect CAN/LIN wiring harness for damage, corrosion, or poorly seated connectors
- Check network termination resistors (typically ~60 ohms across CAN H/L) and continuity
- Backprobe module connector pins while operating to verify signal voltages
- Review module part numbers and software levels for mismatches and TSBs
Signal parameters
- CAN bus voltage idle: ~2.5V on CAN_H and CAN_L relative to ground
- CAN differential voltage during frames: ~2.0V (dominant) / ~0V (recessive)
- LIN bus idle voltage ~Battery through pull-up (varies by vehicle)
- Message frequency and ID presence for expected module (messages per second)
- Bit error/frame error counters (if available via diagnostic tool)
- CRC or checksum fields in module messages (if supported)
Diagnostic algorithm
- Retrieve all stored and pending U- and P- codes from every module; note module source and timestamp.
- Verify vehicle battery voltage and good chassis/engine ground connections; charge or load-test battery if low.
- Visually inspect all connectors and wiring on the affected bus(s) for corrosion, damage, or loose pins; repair as needed.
- With a scope or CAN diagnostic tool, monitor the bus for valid frames, message IDs, differential voltages, and error frames while exercising systems.
- Check and measure termination resistance across CAN H/L at key network points; repair open/shorted terminators.
- Isolate the issue by disconnecting suspected modules one at a time (when safe) to see if errors clear, identifying a failing node.
- If a module was recently replaced or reprogrammed, confirm correct part number and software calibration; reflash or reprogram per manufacturer procedures.
- Repair any wiring/connector faults, replace failed modules or transceivers as indicated, then clear codes and re-test for recurrence.
- If intermittent, recreate conditions (temperature, vibration) that cause the fault and retest; consider protective routing or shielding for wiring.
- Check manufacturer service information for TSBs or known network issues before module replacement.
Likely causes
- Damaged CAN/LIN wires (chafing, pinched, corrosion) causing bit errors
- Loose or corroded connector pins at modules or junctions
- Failed module sending corrupted messages due to internal fault
- Low battery voltage or poor ground causing communication errors
- Incorrect or incomplete reprogramming after module replacement
- Failed CAN transceiver or physical layer components (terminator resistor open/short)
Fault status
Status
Invalid data received from another control module on vehicle network
Repair difficulty: Medium
Diagnostic time: 1.0-3.5 hours
Similar codes
Repair manuals
Brands with available manuals
8,118
The library contains 8,118 repair and diagnostic manuals. Choose a brand to open the full manual tree by year, model and trim.
Your experience will help others
+100 karma for a short comment :)
Was this AI description helpful?
Your feedback helps improve AI descriptions.
👍 Like
0
👎 Dislike
0
Send to email