Automotive Diagnostics
Glossary & Terminology

Term used to describe the many systems and emerging technologies in modern vehicles, existing in some as early as 2006. Includes Lidar, Radar, sonar, object detection, lane keep assist, blind spot detection, thermal imaging (night vision), brake assist, active cruise control, and active lighting. All systems use sensors and cameras that require calibrations.

A scan tool developed and marketed outside of OEM dealer sources. Capabilities can range from basic to highly specialized, depending on the software packages purchased for the tool.

A laptop, PC, or tablet based software package that uses the device's computing resources and connects to a vehicle via USB, Bluetooth, or Wi-Fi (VCI). Both OEM and aftermarket versions are available.

A suitable battery charger, voltage maintainer, or fully charged jump box connected during KOEO mode — especially critical during programming. Prevents vehicle voltage falling below normal levels.

A vehicle communication protocol replacing older protocols since 2003. Primarily a 2-wire network connecting modules to the diagnostic (DLC) connector. As of 2008, all US vehicles must implement CAN.

Not programming — the process of putting a module into "learn mode" with predetermined standard set points. Like setting your bathroom scale to "0" before weighing. Must be done with a compatible scan tool.

Similar to calibration but not as detailed as programming. Coding must be entered into modules using a scan tool when a component has been replaced or the system reset.

A DTC type requiring a road test. Specific conditions must be met before the module runs a system function self-check. Some DTCs of this type require multiple drive cycles before a fault can detect and trigger.

A DTC self-check type where circuits and conditions are monitored at all times the key is on or engine is running. A code sets whenever a fault is present.

Diagnostic Trouble Codes created during the normal course of performing required repair operations. Disconnecting sensors, lights, modules, wiring, and the battery during repairs triggers multiple fault codes.

The 16-pin, D-shaped connector used to connect scan tools to vehicle data networks. Located within a mandated distance from the driver's steering wheel, usually beneath the knee bolster.

Codes obtained during a vehicle scan, specific to module functions and outputs. A DTC does not indicate a specific component has failed, but that there is trouble within the component or its circuit.

A specific vehicle operating sequence reproducing all driving scenarios: starting, driving through all gears, full warm-up to operating temperature, steering both directions, stop, idle, and shut off.

A calibration procedure requiring the vehicle to be put into a learn state and then operated under specified conditions until calibration is complete.

Something not working on the vehicle as designed. Faults monitored by a module result in a DTC being stored if the fault is outside expected parameters.

A snapshot of sensor data captured at the exact moment a DTC was set. Required for all OBD2 emissions codes. Used by technicians to determine operating conditions of the fault.

A fault that is continuously monitored and is present at the time of scan — the code will not clear. The fault must be located and repaired before any code can be cleared.

A fault code that is not currently active. The code was set at some point but has since passed the module's subsequent self-check.

A fault that is conditionally or intermittently present, possibly creating symptoms only under specific circumstances. Intermittent faults are often the most difficult to locate and correct.

Vehicle electrical systems powered without the engine running. Battery support is required for extended procedures as the battery drains quickly.

The vehicle is on with the engine running, or in "ready mode" for hybrid vehicles.

Real-time sensor input values, circuit resistance values, and module output states displayed on a scan tool during an active vehicle connection.

Any warning lamp on the instrument cluster — Check Engine, ABS, Airbag/SRS, Traction Control, Oil Pressure, Coolant Temperature, Tyre Pressure, and others.

A scan tool equipped only with basic OBD2 emission-control capabilities. Body controls, airbags, ABS, theft deterrent, seat belt data — are not included and require an Enhanced or OEM-level scan tool.

A scan tool function activating individual vehicle components for diagnostic verification — commanding headlamps, cooling fans, A/C compressors, wipers, door locks, and more.

A code that has failed or marginally passed the vehicle's built-in test routines. If it passes 2 or more consecutive self-tests, the pending code self-clears.

A procedure required for most replacement modules. New modules ship with generic base software that cannot operate in any specific vehicle until the correct program file is downloaded from the manufacturer.

Performed before repairs begin. Identifies areas of concern within the vehicle's computer networks, components, and safety systems.

Performed when the vehicle is completely reassembled before final QC. Verifies all required calibrations and programming are completed.

Sources for vehicle repair information, schematics, wiring diagrams, calibration procedures, and diagnostic test procedures from ALLDATA, Mitchell1, Identifix, Haynes Pro, and others.

A type of static calibration used for occupant detection systems, steering angle sensors, brake pedal position sensors, and idle air control "idle learn" procedures.