Code
U0122
Generic
U — Network/User
Lost Communication With Vehicle Dynamics Control Module
Views:
UK: 30
EN: 71
RU: 63
AI status
Completed
Completed
100%
Causes
- Open or shorted CAN bus wiring to the VDC module
- Corroded, loose or damaged connector at the VDC module
- VDC module lost power or ground (bad fuse, relay, or wiring)
- Failed VDC module or internal CAN transceiver
- Network termination resistor missing or incorrect value
- Bus interference or excessive CAN bus voltage from another module
Symptoms
- ABS, traction control, ESP or VDC warning lamp illuminated
- Reduced or disabled stability/traction control functions
- Possible ABS faults or loss of ABS functions under braking
- Multiple U-codes on same network or intermittent communication
- No data available from VDC module on scan tool
What to check
- Use a capable scan tool to confirm U0122 and note any additional U-codes on the CAN network
- Check battery voltage and charging system (low battery can prevent modules from communicating reliably)
- Inspect fuses and relays supplying the VDC module
- Visually inspect VDC module connector for corrosion, bent pins, or water intrusion
- Inspect CAN wiring harness for physical damage, chafing, or recent repairs/aftermarket taps
- Verify other modules on same CAN bus are communicating normally
Signal parameters
- CAN bus idle voltages: CAN_H and CAN_L ~2.5 V (recessive)
- Dominant bus state: CAN_H ≈ 3.5 V, CAN_L ≈ 1.5 V (differential ~2 V)
- Expected termination: ~60 ohms across CAN_H and CAN_L (two 120 Ω resistors in parallel)
- Typical CAN bit rates vary by vehicle (commonly 250 kbps or 500 kbps) — confirm vehicle-specific bus speed with manufacturer data
- VDC module should periodically transmit diagnostic/vehicle dynamics messages (check frequency with a capable data logger)
Diagnostic algorithm
- Record freeze frame and all U-codes; note when the fault occurs (key on, driving, after wash)
- Attempt to communicate with VDC module using scan tool and note error (no response, timeout)
- Check battery voltage (key on engine off) and verify stable supply >12 V; inspect charging system
- Inspect and secure fuses/relays for the VDC module; verify module power and ground pins using a multimeter
- With ignition on, measure CAN_H and CAN_L at the VDC connector (backprobe) and at other known good module connectors; confirm idle voltages ~2.5 V and differential behavior when bus is active
- Measure resistance across CAN_H and CAN_L with power off; expect ≈60 Ω. If open or far from expected, inspect termination resistors and wiring
- If bus voltages or termination are abnormal, inspect wiring harness between VDC and nearest gateway/ECU for damage; repair any pinched or chafed wiring
- If bus appears healthy but module does not respond, disconnect the VDC module and verify whether the rest of network communication is restored (isolates a shorted module)
- Use an oscilloscope or CAN bus analyzer to view waveforms and message traffic; look for noise, missing messages, or collisions
- If VDC module power/ground and CAN transceiver checks fail only at the module, consider module replacement and reprogramming per manufacturer procedures
- After repairs, clear codes, perform relearns/programming if required, and road test to confirm communication restored
Likely causes
- Loose or corroded connector at VDC module
- Blown fuse or faulty power/ground to VDC module
- Damaged CAN_H or CAN_L wiring (chafing, pinched, cut)
- Failed CAN transceiver inside VDC module
- Short to battery or ground on CAN lines due to aftermarket accessory or wiring damage
Fault status
Status
U0122 - Lost Communication With Vehicle Dynamics Control Module (no response from VDC on vehicle CAN network)
Repair difficulty: Medium
Diagnostic time: 1.0-3.0 hours
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Code
U0122
HYUNDAI
U — Network/User
Lost Communication With Vehicle Dynamics Control Module | Lost Communication With Vehicle Dynamics Control Module (C-CAN) | CAN TCS Communication
Views:
UK: 14
EN: 48
RU: 46
AI status
Completed
Completed
100%
Causes
- Open or shorted CAN bus wiring to the VDC module
- Corroded, loose or damaged connector at the VDC module
- VDC module lost power or ground (bad fuse, relay, or wiring)
- Failed VDC module or internal CAN transceiver
- Network termination resistor missing or incorrect value
- Bus interference or excessive CAN bus voltage from another module
Symptoms
- ABS, traction control, ESP or VDC warning lamp illuminated
- Reduced or disabled stability/traction control functions
- Possible ABS faults or loss of ABS functions under braking
- Multiple U-codes on same network or intermittent communication
- No data available from VDC module on scan tool
What to check
- Use a capable scan tool to confirm U0122 and note any additional U-codes on the CAN network
- Check battery voltage and charging system (low battery can prevent modules from communicating reliably)
- Inspect fuses and relays supplying the VDC module
- Visually inspect VDC module connector for corrosion, bent pins, or water intrusion
- Inspect CAN wiring harness for physical damage, chafing, or recent repairs/aftermarket taps
- Verify other modules on same CAN bus are communicating normally
Signal parameters
- CAN bus idle voltages: CAN_H and CAN_L ~2.5 V (recessive)
- Dominant bus state: CAN_H ≈ 3.5 V, CAN_L ≈ 1.5 V (differential ~2 V)
- Expected termination: ~60 ohms across CAN_H and CAN_L (two 120 Ω resistors in parallel)
- Typical CAN bit rates vary by vehicle (commonly 250 kbps or 500 kbps) — confirm vehicle-specific bus speed with manufacturer data
- VDC module should periodically transmit diagnostic/vehicle dynamics messages (check frequency with a capable data logger)
Diagnostic algorithm
- Record freeze frame and all U-codes; note when the fault occurs (key on, driving, after wash)
- Attempt to communicate with VDC module using scan tool and note error (no response, timeout)
- Check battery voltage (key on engine off) and verify stable supply >12 V; inspect charging system
- Inspect and secure fuses/relays for the VDC module; verify module power and ground pins using a multimeter
- With ignition on, measure CAN_H and CAN_L at the VDC connector (backprobe) and at other known good module connectors; confirm idle voltages ~2.5 V and differential behavior when bus is active
- Measure resistance across CAN_H and CAN_L with power off; expect ≈60 Ω. If open or far from expected, inspect termination resistors and wiring
- If bus voltages or termination are abnormal, inspect wiring harness between VDC and nearest gateway/ECU for damage; repair any pinched or chafed wiring
- If bus appears healthy but module does not respond, disconnect the VDC module and verify whether the rest of network communication is restored (isolates a shorted module)
- Use an oscilloscope or CAN bus analyzer to view waveforms and message traffic; look for noise, missing messages, or collisions
- If VDC module power/ground and CAN transceiver checks fail only at the module, consider module replacement and reprogramming per manufacturer procedures
- After repairs, clear codes, perform relearns/programming if required, and road test to confirm communication restored
Likely causes
- Loose or corroded connector at VDC module
- Blown fuse or faulty power/ground to VDC module
- Damaged CAN_H or CAN_L wiring (chafing, pinched, cut)
- Failed CAN transceiver inside VDC module
- Short to battery or ground on CAN lines due to aftermarket accessory or wiring damage
Fault status
Status
U0122 - Lost Communication With Vehicle Dynamics Control Module (no response from VDC on vehicle CAN network)
Repair difficulty: Medium
Diagnostic time: 1.0-3.0 hours
Similar codes
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Code
U0122
LAND ROVER
U — Network/User
Lost communication with the vehicle's dynamic control module
Views:
UK: 10
EN: 57
RU: 50
AI status
Completed
Completed
100%
Causes
- Open or shorted CAN bus wiring to the VDC module
- Corroded, loose or damaged connector at the VDC module
- VDC module lost power or ground (bad fuse, relay, or wiring)
- Failed VDC module or internal CAN transceiver
- Network termination resistor missing or incorrect value
- Bus interference or excessive CAN bus voltage from another module
Symptoms
- ABS, traction control, ESP or VDC warning lamp illuminated
- Reduced or disabled stability/traction control functions
- Possible ABS faults or loss of ABS functions under braking
- Multiple U-codes on same network or intermittent communication
- No data available from VDC module on scan tool
What to check
- Use a capable scan tool to confirm U0122 and note any additional U-codes on the CAN network
- Check battery voltage and charging system (low battery can prevent modules from communicating reliably)
- Inspect fuses and relays supplying the VDC module
- Visually inspect VDC module connector for corrosion, bent pins, or water intrusion
- Inspect CAN wiring harness for physical damage, chafing, or recent repairs/aftermarket taps
- Verify other modules on same CAN bus are communicating normally
Signal parameters
- CAN bus idle voltages: CAN_H and CAN_L ~2.5 V (recessive)
- Dominant bus state: CAN_H ≈ 3.5 V, CAN_L ≈ 1.5 V (differential ~2 V)
- Expected termination: ~60 ohms across CAN_H and CAN_L (two 120 Ω resistors in parallel)
- Typical CAN bit rates vary by vehicle (commonly 250 kbps or 500 kbps) — confirm vehicle-specific bus speed with manufacturer data
- VDC module should periodically transmit diagnostic/vehicle dynamics messages (check frequency with a capable data logger)
Diagnostic algorithm
- Record freeze frame and all U-codes; note when the fault occurs (key on, driving, after wash)
- Attempt to communicate with VDC module using scan tool and note error (no response, timeout)
- Check battery voltage (key on engine off) and verify stable supply >12 V; inspect charging system
- Inspect and secure fuses/relays for the VDC module; verify module power and ground pins using a multimeter
- With ignition on, measure CAN_H and CAN_L at the VDC connector (backprobe) and at other known good module connectors; confirm idle voltages ~2.5 V and differential behavior when bus is active
- Measure resistance across CAN_H and CAN_L with power off; expect ≈60 Ω. If open or far from expected, inspect termination resistors and wiring
- If bus voltages or termination are abnormal, inspect wiring harness between VDC and nearest gateway/ECU for damage; repair any pinched or chafed wiring
- If bus appears healthy but module does not respond, disconnect the VDC module and verify whether the rest of network communication is restored (isolates a shorted module)
- Use an oscilloscope or CAN bus analyzer to view waveforms and message traffic; look for noise, missing messages, or collisions
- If VDC module power/ground and CAN transceiver checks fail only at the module, consider module replacement and reprogramming per manufacturer procedures
- After repairs, clear codes, perform relearns/programming if required, and road test to confirm communication restored
Likely causes
- Loose or corroded connector at VDC module
- Blown fuse or faulty power/ground to VDC module
- Damaged CAN_H or CAN_L wiring (chafing, pinched, cut)
- Failed CAN transceiver inside VDC module
- Short to battery or ground on CAN lines due to aftermarket accessory or wiring damage
Fault status
Status
U0122 - Lost Communication With Vehicle Dynamics Control Module (no response from VDC on vehicle CAN network)
Repair difficulty: Medium
Diagnostic time: 1.0-3.0 hours
Similar codes
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Workshop Manual199,00 UAH
Your experience will help others
+100 karma for a short comment :)
Was this AI description helpful?
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👍 Like
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