Code
U0297
Generic
U — Network/User
Lost Communication With AC/DC Converter Control Module B
Views:
UK: 19
EN: 25
RU: 18
AI status
Completed
Completed
100%
Causes
- Open or shorted CAN/LIN communication wiring between control module B and the network
- Corroded, loose, damaged or improperly seated connector at the AC/DC converter control module B
- Blown fuse, relay, or loss of module supply (power or ground)
- Failed AC/DC converter control module B
- Network interruption from another device (bus off condition, missing termination)
- Software/firmware error or module not programmed/configured
Symptoms
- DTC U0297 stored and/or MIL/warning lamp illuminated
- Reduced or disabled charging/conversion functions (loss of auxiliary 12V from converter)
- Loss of related systems that rely on converter data (charge management, displays)
- Intermittent or permanent electrical faults for accessories powered by the converter
- Possible limp-home mode depending on vehicle design
What to check
- Connect a diagnostic scan tool and confirm U0297 and any related network codes (U0073, U0100, etc.)
- Check for other AC/DC converter related codes (module A, B, communications) in all modules
- Visually inspect connectors and wiring to converter control module B for damage, corrosion, or water ingress
- Check dedicated fuses and relays for the converter control module and replace if blown
- Verify module supply voltage and ground at the module connector with key ON
- Backprobe and measure CAN High and CAN Low voltages at the module connector and at a known good network point
Signal parameters
- CAN Bus idle: CAN_H ≈ 2.5–3.5 V, CAN_L ≈ 1.5–2.5 V (both near 2.5 V nominal when recessive)
- CAN Bus dominant: CAN_H rises ~1.5 V above recessive, CAN_L falls ~1.0 V below recessive (differential ~2 V)
- Expected termination resistance across CAN H/L ≈ 60 ohms (two 120Ω resistors in parallel)
- Module supply: nominal 12 V system; expected presence of ignition-switched and battery power pins when required
Diagnostic algorithm
- Read and record all stored and pending codes and freeze-frame data from every control module; note related network codes.
- Cycle ignition and attempt module communication with a scan tool. Confirm the module ID is absent or not responding.
- Visually inspect converter B connector and wiring for damage, corrosion, looseness, or evidence of water.
- With ignition ON (engine OFF unless specified), verify power and ground circuits at converter B connector using a DMM.
- Backprobe CAN_H and CAN_L at converter connector and at a known-good network node. Verify voltages and check for activity while scanning.
- Measure resistance between CAN_H and CAN_L with ignition OFF to confirm ~60 ohms termination. Inspect for shorts to battery or ground on each line.
- If wiring and power/ground are good, disconnect other modules on the same branch (if serviceable) to isolate the fault and re-check communication.
- If communication is restored when converter is disconnected, suspect converter module fault. If not, trace harness for opens/shorts or replace/repair wiring and connectors.
- If module replacement is required, obtain correct part and any required programming/calibration. Clear codes and verify repair by road test and rescanning.
- If problem persists, consult manufacturer technical service bulletins for software updates or known network issues.
Likely causes
- Intermittent or broken CAN high/low wires at the converter connector or along harness
- Poor ground or low battery/ignition supply to the converter control module
- Water intrusion or corrosion at the module connector
- Failed converter control module (internal failure)
- Faulty termination resistor or short to battery/ground on the CAN bus
Fault status
Status
Lost Communication With AC/DC Converter Control Module B — module not responding on vehicle communication network.
Repair difficulty: Medium
Diagnostic time: 1.0-3.0 hours
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Code
U0297
HYUNDAI
U — Network/User
Lost Communication With AC to DC Converter Control Module “B”
Views:
UK: 12
EN: 19
RU: 14
AI status
Completed
Completed
100%
Causes
- Open or shorted CAN/LIN communication wiring between control module B and the network
- Corroded, loose, damaged or improperly seated connector at the AC/DC converter control module B
- Blown fuse, relay, or loss of module supply (power or ground)
- Failed AC/DC converter control module B
- Network interruption from another device (bus off condition, missing termination)
- Software/firmware error or module not programmed/configured
Symptoms
- DTC U0297 stored and/or MIL/warning lamp illuminated
- Reduced or disabled charging/conversion functions (loss of auxiliary 12V from converter)
- Loss of related systems that rely on converter data (charge management, displays)
- Intermittent or permanent electrical faults for accessories powered by the converter
- Possible limp-home mode depending on vehicle design
What to check
- Connect a diagnostic scan tool and confirm U0297 and any related network codes (U0073, U0100, etc.)
- Check for other AC/DC converter related codes (module A, B, communications) in all modules
- Visually inspect connectors and wiring to converter control module B for damage, corrosion, or water ingress
- Check dedicated fuses and relays for the converter control module and replace if blown
- Verify module supply voltage and ground at the module connector with key ON
- Backprobe and measure CAN High and CAN Low voltages at the module connector and at a known good network point
Signal parameters
- CAN Bus idle: CAN_H ≈ 2.5–3.5 V, CAN_L ≈ 1.5–2.5 V (both near 2.5 V nominal when recessive)
- CAN Bus dominant: CAN_H rises ~1.5 V above recessive, CAN_L falls ~1.0 V below recessive (differential ~2 V)
- Expected termination resistance across CAN H/L ≈ 60 ohms (two 120Ω resistors in parallel)
- Module supply: nominal 12 V system; expected presence of ignition-switched and battery power pins when required
Diagnostic algorithm
- Read and record all stored and pending codes and freeze-frame data from every control module; note related network codes.
- Cycle ignition and attempt module communication with a scan tool. Confirm the module ID is absent or not responding.
- Visually inspect converter B connector and wiring for damage, corrosion, looseness, or evidence of water.
- With ignition ON (engine OFF unless specified), verify power and ground circuits at converter B connector using a DMM.
- Backprobe CAN_H and CAN_L at converter connector and at a known-good network node. Verify voltages and check for activity while scanning.
- Measure resistance between CAN_H and CAN_L with ignition OFF to confirm ~60 ohms termination. Inspect for shorts to battery or ground on each line.
- If wiring and power/ground are good, disconnect other modules on the same branch (if serviceable) to isolate the fault and re-check communication.
- If communication is restored when converter is disconnected, suspect converter module fault. If not, trace harness for opens/shorts or replace/repair wiring and connectors.
- If module replacement is required, obtain correct part and any required programming/calibration. Clear codes and verify repair by road test and rescanning.
- If problem persists, consult manufacturer technical service bulletins for software updates or known network issues.
Likely causes
- Intermittent or broken CAN high/low wires at the converter connector or along harness
- Poor ground or low battery/ignition supply to the converter control module
- Water intrusion or corrosion at the module connector
- Failed converter control module (internal failure)
- Faulty termination resistor or short to battery/ground on the CAN bus
Fault status
Status
Lost Communication With AC/DC Converter Control Module B — module not responding on vehicle communication network.
Repair difficulty: Medium
Diagnostic time: 1.0-3.0 hours
Similar codes
Your experience will help others
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