Direct answer
ISO 16750-2 is part 2 of ISO 16750 and specifies the electrical load tests for electrical and electronic equipment in road vehicles, covering the DC supply voltage range, overvoltage, superimposed alternating voltage, voltage dip and recovery, reverse voltage, ground offset, open circuit and short circuit. Abnormalities in the vehicle power supply are largely covered by this part.
The six parts of ISO 16750 and what each covers
| Part | Content |
|---|---|
| Part 1 | Terms and general provisions |
| Part 2 | Electrical loads |
| Part 3 | Mechanical loads (vibration, shock) |
| Part 4 | Climatic loads (temperature, humidity, salt mist, ingress protection, etc.) |
| Part 5 | Chemical loads |
| Part 6 | Vehicle-level environment and others |
Part 2 is often mistaken for a subset of environmental testing. In fact it covers only conditions related to power supply and electrical connection, with no temperature or vibration. In an environmental test plan, Part 2 sits alongside Parts 3 and 4 — it is not a container for them.
The main test items in Part 2
| Test item | What it simulates | Typical concern |
|---|---|---|
| DC supply voltage range | Alternator output variation, different battery states of charge | All electronic components |
| Overvoltage | Voltage regulator failure and similar faults | 12 V / 24 V system components |
| Superimposed alternating voltage | Rectifier ripple | Modules sensitive to ripple |
| Slow decrease and increase of supply voltage | Voltage change during cranking | All electronic components |
| Voltage dip and recovery | The instant of engine start | All electronic components |
| Reverse voltage | Jump start with reversed polarity, servicing error | All electronic components |
| Ground offset | Poor grounding, potential difference between ground points | Sensors and signal-level devices |
| Open circuit | Broken harness, disconnected connector | Input and output circuits |
| Short circuit | Harness shorting | Output driver devices |
Functional status classes A / B / C / D
Immunity and electrical load tests do not simply ask "did it break" — they look at functional behaviour during and after the test:
- Class A: all functions perform as designed during and after the test
- Class B: temporary degradation is allowed during the test, with automatic recovery afterwards
- Class C: functional deviation is allowed during the test, but a manual reset or restart is needed to recover
- Class D: repair or replacement is needed to recover after the test
Which class a given item must reach is specified by the OEM or the customer standard. For the same product, different items may carry different classes.
Its relationship to the Chinese standard
GB/T 28046.2 is an identical adoption of ISO 16750-2, with the same technical content. Domestic OEMs mostly use GB/T 28046; export work and international customers mostly use ISO 16750, and the report should state the specific year version.
Two common misunderstandings
Assuming Part 2 covers all electrically related testing. Conducted immunity and transient immunity in EMC belong to the ISO 7637 series and to CISPR 25 / ISO 11452 — they are not in Part 2.
Ignoring the severity attached to the mounting location. Many parameters in Part 2 are also graded by system voltage class and mounting location, and taking the default level is often too lenient.
Where we stand
TMC LAB holds both CMA and CNAS accreditation and covers the electrical, mechanical and climatic load items of the ISO 16750 and GB/T 28046 series. We can list the Part 2 items one by one against your customer's standard for checking.
Related pages for this question
Last updated Technical criteria follow the current standards and the agreed scope; please confirm the specific project with the lab.
