Reference
Glossary
Every acronym and identifier these docs use, explained once.
This glossary explains the labels and abbreviations used in Hanterill and its guides.
If you are new to vehicle diagnostics, start with the Diagnostics group below: those are the terms you will see on your very first scan.
Diagnostics
- ECUElectronic Control Unit
- A small computer inside the car that runs one job, such as the brakes or the windows.
- DTCDiagnostic Trouble Code
- A code a module stores when it detects a problem, printed as seven characters such as B171D57.
- DIDData Identifier
- A number used to ask a module for one specific value, such as its serial number or cell voltages.
- SoHState of Health
- How much capacity a battery has left compared with when it was new, as a percentage.
- SoCState of Charge
- How full the battery is right now, as a percentage of its current capacity.
- PIDParameter Identifier
- A channel of live data that can be sampled on a schedule, such as pack current or motor speed.
- NRCNegative Response Code
- The reason a module refused a request: unsupported service, wrong session, too busy, and so on.
- Freeze frameStored snapshot record
- The conditions a module recorded at the moment a fault occurred, such as speed and temperature.
- CoverageDiagnostic coverage
- How many of the modules a scan planned to read actually answered, reported honestly including the failures.
- EPBElectric Parking Brake
- The electronic handbrake, whose calipers can be retracted for pad or disc work.
Protocols
- DoIPDiagnostics over Internet Protocol (ISO 13400)
- The standard that lets diagnostic messages travel over ordinary Ethernet to the car.
- UDSUnified Diagnostic Services (ISO 14229)
- The language of the questions: read a value, read fault codes, open a session, clear codes.
- ENETEthernet diagnostic cable (OBD-II to RJ45)
- The passive copper cable that carries Ethernet from your laptop to the car's diagnostic port.
- OBD-IIOn-Board Diagnostics, second generation
- The standard diagnostic socket under the dashboard, required on cars since the 1990s.
- RJ45Registered Jack 45
- The standard Ethernet plug, the same one a home network cable uses.
- TCPTransmission Control Protocol
- The reliable, ordered connection type. Diagnostic messages travel over TCP on port 13400.
- UDPUser Datagram Protocol
- The fire-and-forget message type used to announce a vehicle on the local network.
- ISOInternational Organization for Standardization
- The body that publishes the standards this tool implements, such as ISO 13400 and ISO 14229.
- SAESociety of Automotive Engineers
- The body behind the fault-code naming standard (SAE J2012) that gives DTCs their letters and digits.
- LINLocal Interconnect Network
- A cheap, slow bus used for simple parts such as a door switch or a mirror.
- CANController Area Network
- The classic in-car bus. Some older platforms serve battery data over it rather than over Ethernet.
- VINVehicle Identification Number
- The car's 17-character identity, shown on the Vehicle screen and in reports, with one-click masking when sharing exports.
- OTAOver-the-Air
- A software update delivered remotely rather than at a workshop.
Battery and high voltage
- BECMBattery Energy Control Module
- The computer that manages the traction battery and reports its health, charge and cell voltages.
- BMSBattery Monitoring Sensor
- The sensor on the 12 V battery that reports its state to the car.
- HVHigh Voltage
- The several-hundred-volt system that drives the motors. Hazardous, and never to be touched without training.
- Cell groupSeries cell group
- A set of battery cells wired in series that the module reports as one voltage, the unit the cell matrix shows.
- OBCOn-Board Charger
- The module that converts AC mains into DC to charge the pack.
- IHFAInverter, High voltage Front Axle
- The module that turns battery DC into motor drive current for the front axle.
- IEMInverter, ERAD Module
- The inverter for the rear axle motor (ERAD: Electric Rear Axle Drive).
- HVACHeating, Ventilation and Air Conditioning
- The climate system: heat pump, heater circuit, compressor and blend doors.
Modules
- CEMCentral Electronic Module
- The car's central body computer, which also holds the gateway to the diagnostic network.
- VGMVehicle Gateway Module
- The firewall between the outside diagnostic connection and the car's internal networks.
- TCAMTelematics and Connectivity Antenna Module
- The module that carries the cellular modem, GNSS position and the emergency backup battery.
- IHUInfotainment Head Unit
- The main screen computer (Android Automotive on the reference platform).
- VCU1Vehicle Control Unit 1
- The module that coordinates drive and torque across the axles.
- DIMDriver Information Module
- The instrument cluster behind the steering wheel, and the keeper of the service counter.
- SRSSupplemental Restraint System
- The airbag and restraint controllers. A live fault here is treated as safety-critical.
- BCM2Brake Control Module 2
- The ABS, stability control and parking-brake controller.
- PSCMPower Steering Control Module
- The electric power steering controller.
- SASSteering Angle Sensor
- The sensor that reports how far and how fast the wheel is turned.
- ASDMActive Safety Domain Master
- The module that fuses camera and radar data for driver-assistance features.
- ADASAdvanced Driver Assistance Systems
- The driver-assistance features: forward camera, radar, surround view and their calibration.
- ECMEngine Control Module
- The combustion engine controller. Present on the hybrid and PHEV variants, silent on a BEV.
- TCMTransmission Control Module
- The gearbox controller on combustion and hybrid variants.
Platforms and bodies
- CMACompact Modular Architecture
- The platform under the Polestar 2 and the smaller electric Volvos, and the one Hanterill was built on.
- SPAScalable Product Architecture
- The larger Volvo platform, mostly plug-in hybrids and combustion cars. Provisional DoIP connection, fault scans and early battery reads are wired, while deeper battery verification continues.
- SEASustainable Experience Architecture
- The Geely-family electric platform under the EX30 class. Definitions exist and still need testing on more cars.
- SPA2Second-generation Scalable Product Architecture
- The newest large platform (EX90, Polestar 3). Under investigation, not usable for diagnostics.
- BEVBattery Electric Vehicle
- A car driven purely by a battery and electric motors, with no combustion engine.
- PHEVPlug-in Hybrid Electric Vehicle
- A car with both a combustion engine and a chargeable battery.
- ICEInternal Combustion Engine
- A petrol or diesel engine. The CMA platform has hybrid variants, so the engine side is catalogued too.
- GNSSGlobal Navigation Satellite System
- The satellite positioning system (GPS and its siblings) reported by the telematics module.
Pairs of terms that are easy to mix up#
A few terms sound similar but measure very different things:
- SoH versus SoC: State of Health (SoH) is how much usable storage capacity the battery pack still holds compared with when it left the factory. State of Charge (SoC) is how full the battery is right now, like a fuel gauge. A battery pack can be at 93% State of Health while sitting at 20% State of Charge.
- Battery SoH, cell delta, and the Inspection Report score: Three separate numbers. SoH is reported by the battery management module as an overall capacity percentage. Cell delta is the voltage gap (in millivolts) between the highest and lowest individual cells at that moment. The Inspection Report score is an overall 0-to-100 vehicle evaluation that combines battery health, cell balance, fault codes, and module responses. See Battery diagnostics.
- ECU versus DID: An ECU (Electronic Control Unit) is a physical computer box inside the car (such as the brake controller or climate controller). A DID (Data Identifier) is a single numbered measurement or setting inside that computer (such as cabin temperature or software version). One ECU answers hundreds of different DIDs.
- DTC versus freeze frame: A DTC (Diagnostic Trouble Code) is the fault code itself, telling you what went wrong. A freeze frame is the snapshot of vehicle conditions (speed, voltage, temperature, mileage) recorded at the exact moment that fault occurred.
- Compatible versus supported: Compatible means Hanterill can connect to the vehicle and read core identification and fault codes. Supported means the full set of subsystem readings and formulas has been verified on live cars of that platform. See Supported vehicles.
- Provisional versus verified: A reading marked verified has had its unit, scaling formula, and physical range confirmed on live vehicles. A reading marked provisional is decoded using a working formula that is still being cross-checked across additional models and trim levels.
Common diagnostic actions explained#
When Hanterill communicates with your car over the diagnostic cable, almost everything it does comes down to six standard types of messages:
- Open a diagnostic session
- Tells a module to wake up its diagnostic interface so it can answer detailed identification and sensor reads.
- Keep-alive heartbeat (Tester Present)
- A quiet periodic signal sent while a scan is running so the car does not put its modules back to sleep mid-read.
- Read a data value
- Asks a module for one specific measurement or identity record (such as battery voltage, coolant temperature, or VIN).
- Read fault codes
- Asks a module to list any stored, pending, or permanent Diagnostic Trouble Codes and their freeze-frame snapshots.
- Clear stored fault codes
- Instructs a module to erase its stored fault history. Because this changes the car's state, Hanterill always asks for your confirmation first.
- Run a service routine
- Starts a built-in maintenance procedure inside a module (such as retracting the parking brake for pad replacement or resetting the service reminder) after you confirm the safety prompt.
Next#
- Screen tour: see where these terms appear inside the app.
- ECU reference: every control unit code and what it manages in the car.