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U3003 Network

Battery Voltage

The control module detected battery voltage outside its acceptable operating window. Either too low (drained battery, weak charging) or too high (charging system overvoltage).

Affected components

  • Battery
  • Alternator
  • Charging system

Common causes

  • High likelihood: Battery aged or sulfated
  • Medium likelihood: Alternator regulator fault (over- or undervoltage)
  • Low likelihood: Gateway module routing CAN messages incorrectly

Possible symptoms

  • Multiple warning lights may illuminate
  • Affected modules may go into limp mode or shut down
  • Specific functions inoperative depending on module
  • Diagnostic tools may show communication faults

Diagnostic notes

  • The malfunction indicator lamp may illuminate
  • A drive cycle may be required after repair

Sources

Diagnostic information is provided for reference only. Confirm the code with a compatible scan tool and follow the vehicle manufacturer's service procedures before replacing components.

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