{
  "node": {
    "id": "term:dtc",
    "type": "Term",
    "label": "Diagnostic trouble code",
    "properties": {
      "id": "dtc",
      "name": "Diagnostic trouble code",
      "abbr": "DTC",
      "aka": [
        "fault code"
      ],
      "section": "topic-data",
      "definition": "A coded fault a controller stores when a check fails — a cell overvoltage, a sensor out of range, an isolation fault — with a status and often a snapshot of conditions when it occurred. Reading and interpreting DTCs is the first step of any battery root-cause analysis.",
      "related": [
        "uds",
        "bmu",
        "insulation-resistance",
        "freeze-frame"
      ],
      "url": "https://lemonergy.com/learn/glossary/dtc/",
      "mentions": [
        "insulation-fault"
      ]
    }
  },
  "edges": [
    {
      "id": "edge:4129",
      "source": "term:dtc",
      "target": "topic:topic-data",
      "type": "belongsTo",
      "properties": {
        "sourceFile": "terms.json"
      }
    },
    {
      "id": "edge:4130",
      "source": "term:dtc",
      "target": "term:uds",
      "type": "relatedTo",
      "properties": {
        "sourceFile": "terms.json",
        "meaning": "Related context; not a causal claim"
      }
    },
    {
      "id": "edge:4131",
      "source": "term:dtc",
      "target": "term:bmu",
      "type": "relatedTo",
      "properties": {
        "sourceFile": "terms.json",
        "meaning": "Related context; not a causal claim"
      }
    },
    {
      "id": "edge:4132",
      "source": "term:dtc",
      "target": "term:insulation-resistance",
      "type": "relatedTo",
      "properties": {
        "sourceFile": "terms.json",
        "meaning": "Related context; not a causal claim"
      }
    },
    {
      "id": "edge:4133",
      "source": "term:dtc",
      "target": "term:freeze-frame",
      "type": "relatedTo",
      "properties": {
        "sourceFile": "terms.json",
        "meaning": "Related context; not a causal claim"
      }
    },
    {
      "id": "edge:mentions/dtc/insulation-fault",
      "source": "term:dtc",
      "target": "term:insulation-fault",
      "type": "mentions",
      "properties": {
        "sourceFile": "terms.json",
        "method": "build_glossary.mention_index + mentions",
        "field": "definition",
        "meaning": "Text mention; not a causal claim"
      }
    }
  ],
  "neighbors": [
    {
      "id": "topic:topic-data",
      "type": "Topic",
      "label": "Data, communication and electronics",
      "properties": {
        "id": "topic-data",
        "name": "Data, communication and electronics",
        "lede": "The control units, chips, protocols and file formats through which a battery is measured, controlled and logged.",
        "context": "Separate quantities from encoding and transport.",
        "example": "2500 in a log might mean 25.00 °C, 2.5 V or raw counts. Units and scale must accompany the value.",
        "lesson_url": "https://lemonergy.com/learn/fundamentals/battery-basics/",
        "lesson_label": "Open battery basics"
      }
    },
    {
      "id": "term:uds",
      "type": "Term",
      "label": "Unified diagnostic services",
      "properties": {
        "id": "uds",
        "name": "Unified diagnostic services",
        "abbr": "UDS",
        "aka": [
          "ISO 14229"
        ],
        "section": "topic-data",
        "definition": "The standard diagnostic protocol of vehicle controllers, ISO 14229: services to read data and fault codes, run routines, change sessions and flash firmware. A service tool talks UDS to the BMU over CAN to read cell data, clear faults or update software.",
        "related": [
          "dtc",
          "flashing",
          "can-bus",
          "odx",
          "ecu"
        ],
        "url": "https://lemonergy.com/learn/glossary/uds/",
        "mentions": [
          "bmu",
          "firmware"
        ]
      }
    },
    {
      "id": "term:bmu",
      "type": "Term",
      "label": "Battery management unit",
      "properties": {
        "id": "bmu",
        "name": "Battery management unit",
        "abbr": "BMU",
        "aka": [
          "BMS master",
          "master BMS"
        ],
        "section": "topic-data",
        "definition": "The master controller of a battery management system: it collects cell voltages and temperatures from the monitoring boards, runs the state estimation and protection logic, drives the contactors and talks to the vehicle. In some architectures the same name is used for a per-module slave, so a datasheet’s block diagram is the safe reference.",
        "related": [
          "bms",
          "cell-supervision-circuit",
          "bcu",
          "contactor",
          "can-bus",
          "bms-power-modes"
        ],
        "url": "https://lemonergy.com/learn/glossary/bmu/",
        "mentions": [
          "datasheet"
        ]
      }
    },
    {
      "id": "term:insulation-resistance",
      "type": "Term",
      "label": "Insulation resistance",
      "properties": {
        "id": "insulation-resistance",
        "name": "Insulation resistance",
        "aka": [
          "isolation resistance",
          "IMD"
        ],
        "section": "topic-hvsafety",
        "definition": "The resistance between the high-voltage circuit and the vehicle chassis, which must stay above about 100 Ω per volt of pack voltage so a person touching the chassis is safe. An insulation monitoring device measures it continuously.",
        "unit": "Ω/V",
        "related": [
          "pack-voltage",
          "high-voltage-interlock",
          "functional-safety",
          "insulation-test"
        ],
        "url": "https://lemonergy.com/learn/glossary/insulation-resistance/",
        "mentions": [
          "volt"
        ]
      }
    },
    {
      "id": "term:freeze-frame",
      "type": "Term",
      "label": "Freeze frame",
      "properties": {
        "id": "freeze-frame",
        "name": "Freeze frame",
        "aka": [
          "snapshot data",
          "extended data record"
        ],
        "section": "topic-data",
        "definition": "The set of values a controller saves at the moment a fault is detected — SOC, temperatures, current, the worst cell — attached to the trouble code. It is often the only record of the conditions that caused an intermittent fault.",
        "related": [
          "dtc",
          "uds",
          "data-logger"
        ],
        "url": "https://lemonergy.com/learn/glossary/freeze-frame/",
        "mentions": [
          "state-of-charge"
        ]
      }
    },
    {
      "id": "term:insulation-fault",
      "type": "Term",
      "label": "Insulation fault",
      "properties": {
        "id": "insulation-fault",
        "name": "Insulation fault",
        "aka": [
          "ground fault",
          "earth fault",
          "isolation fault",
          "chassis fault"
        ],
        "section": "topic-hvsafety",
        "definition": "An unintended low-resistance path between a high-voltage conductor and the chassis, from damaged insulation, coolant leaks or moisture. A vehicle’s high-voltage system floats free of the chassis, so a single fault drives no current; a second on the other pole completes a circuit through the chassis. The insulation monitor therefore flags the first before a second can arise.",
        "related": [
          "insulation-resistance",
          "insulation-test",
          "equipotential-bonding",
          "dtc",
          "voltage-class"
        ],
        "url": "https://lemonergy.com/learn/glossary/insulation-fault/",
        "mentions": []
      }
    }
  ]
}