U0297

Code

Generic U — Network/User

Lost Communication With AC/DC Converter Control Module B

Brand: Generic

Type: U — Network/User

Views: UK: 25 EN: 29 RU: 26

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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

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

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

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

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.

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