Automotive Voltage Test — ISO 16750-2 / ISO 7637

What Is Voltage?

The voltage test verifies a component's resistance to voltage variations encountered in the vehicle electrical system — undervoltage, overvoltage, reverse polarity, voltage sag during cranking, and transients such as load dump. The vehicle network does not behave like a stable laboratory source; these tests represent real conditions.

Purpose of Voltage

The purpose is to show that the component is not damaged by network disturbances and retains its defined functional status.

Which Products Is Voltage Applied To?

Electronic control units (ECUs)
Sensors and actuators
Instrument-cluster and multimedia units
Lighting modules
Power-electronics units

In Which Sectors Is Voltage Used?

AutomotiveElectrical & Electronics

Standards Related to Voltage

ISO 16750-2Environmental conditions in vehicle electrical/electronic equipment test
ISO 7637-2electrical transients conducted in vehicles test
ISO 7637-3electrical transients conducted in vehicles test
LV 124
VW 80000

Voltage Conditions

Supply-voltage range: Within the declared operating range; verification at the lower and upper limits
Transients: ISO 7637-2 pulses (1, 2a, 2b, 3a, 3b, 4) and the load-dump pulse (5a/5b)
Functional status: Evaluated according to the A–E classification defined in ISO 16750

Equipment for Voltage

Programmable DC power supply
Transient pulse generator
Oscilloscope
Load simulator and interface box
Data logger and function-monitoring system

Sample Requirements for Voltage

Component and original wiring harness
An interface suited to function monitoring must be provided
The declared operating voltage range and current draw must be stated
Since some tests may be destructive, multiple specimens may be required

Duration of Voltage

A typical voltage test set takes a few days; comprehensive OEM specifications such as LV 124 can extend to weeks.

Voltage Procedure

1The component is connected and function monitoring is set up.
2The reference function is verified at nominal voltage.
3The voltage range is swept at the lower and upper limits.
4The cranking voltage profile is applied.
5Reverse-polarity and overvoltage tests are performed.
6ISO 7637 transient pulses are applied.
7The functional status is classified for each test.

Voltage Acceptance Criteria

The acceptance criterion is the functional-status class defined in the customer's specification for each test (e.g. Class C after load dump: function is interrupted but recovers on its own). Classes are defined in ISO 16750; the specification determines which class is required for which test.

Evaluation of Results

Functional status is evaluated separately during and after the test. Permanent damage or a loss of function that does not self-recover is the most severe finding.

Voltage Report

Component description and software version
Applied standard and test list
Conditions and waveforms for each test
Functional-status classifications
Post-test component condition

Accreditation

EUROLAB holds internationally recognised accreditation obtained from accreditation bodies party to the IAF and ILAC multilateral recognition arrangements, under ISO/IEC 17025 for laboratory testing, ISO/IEC 17020 for inspection and surveillance, and ISO/IEC 17021-1 and ISO/IEC 17065 for system and product certification. This chain ensures the reports and certificates issued are accepted worldwide.

Whether this test can be offered within accredited scope depends on your product and the standard applied; since accreditation is method-based, the scope is confirmed in writing at the quotation stage.

Scope and authorisations

Related Regulations

OEM electrical specifications (LV 124, VW 80000, etc.)

Otomotiv Testleri — What Does This Testing Field Cover?

The section below describes the field that the Voltage test belongs to; the conditions and acceptance criteria of this particular test are given in the sections above. The scope specific to your product is confirmed in writing at the quotation stage.

Automotive testing shows that a component keeps working under conditions representing the loads it will meet over the life of the vehicle. A vehicle is not a single product but an ENVIRONMENT: vibration, temperature cycling, salt water, stone impact, electrical transients and electromagnetic noise are all present at the same time and for years.

What distinguishes this family is that VEHICLE MANUFACTURER SPECIFICATIONS sit on top of the standards. ISO and SAE publications establish the common ground; but Volkswagen, BMW, Ford, Stellantis, Toyota and Renault define different severity levels, additional tests and different acceptance criteria in their own specifications. For a component, the phrase "complies with automotive standards" is not sufficient on its own; which manufacturer's specification, and which revision of it, must be answered.

The family carries three separate processes together and they are often confused. Homologation covers the type approvals a vehicle needs to enter traffic and runs under state authority. Supplier approval means passing the vehicle manufacturer's own quality and testing requirements and is a commercial relationship. The third is design verification: the engineering team demonstrating that its own design meets its targets.

At component level the test plan is built around the LOCATION OF USE. A module in the engine bay and a module in the boot do not go through the same temperature and vibration profile; a component inside a door and one in the roof console do not see the same water and dust exposure. The ISO 16750 series is the common framework for this location-based approach.

The shift to electric vehicles has reshaped the field. High-voltage safety, insulation coordination, battery safety, charging interface conformity and the electromagnetic behaviour of high-voltage components have been added to the classical automotive test set. In a quiet vehicle, acoustic and vibration expectations have changed too; sounds once masked by the combustion engine are now audible.

The quality system side cannot be separated from testing in this field. A manufacturer under IATF 16949 presents test results in the PPAP file; measurement system analysis, process capability study and the control plan stand around the test report. A single good result is not enough — the process must be shown to be able to repeat it.

Method groups in this field

Environmental and climatic
Temperature cycling, thermal shock, damp heat, salt spray, dust and water ingress (IP), solar radiation. Severity levels vary with the mounting location.
Mechanical
Sine and random vibration, shock, mechanical loads, fastener torque and durability cycles.
Electrical
Supply voltage variations, transients (ISO 7637), reverse polarity, overvoltage, short circuit and sleep current measurements.
EMC
Component emissions (CISPR 25), radiated and conducted immunity (ISO 11452 series), electrostatic discharge (ISO 10605).
Materials and emissions
Odour, fogging and VOC emissions from interior materials; flammability; UV ageing; coating durability and stone impact.
Functional safety and cyber security
Functional safety evidence under ISO 26262 and cyber security engineering under ISO/SAE 21434; these are tied to regulation through UNECE R155 and R156.

Commonly confused in this field

An automotive report without a specification reference is not accepted in the supply chain; which OEM specification and revision was applied must be stated.
Type approval and supplier approval are different processes. A component with E-Mark approval is not thereby considered to have passed the OEM's own acceptance tests.
A result obtained on a prototype does not carry over to series production; PPAP is done with series production parts.
On the EMC side, measuring emissions alone is incomplete; immunity is a separate body of work and is more critical in a vehicle.
On electric vehicle components, high-voltage safety is a distinct competence; classical 12 V test infrastructure is not sufficient.

Which decisions these results support

Supplier component approval and the PPAP file
UNECE type approval and E-Mark marking
Design verification and durability evidence
Root cause analysis of field complaints and warranty returns
Assessing the impact of a design or supplier change

Related Tests

Frequently Asked Questions About Voltage

What is load dump?

It is a high-energy voltage surge arising when the battery connection is broken while the alternator is running. It is one of the most demanding transients for vehicle electronics and is defined as Pulse 5a/5b in ISO 7637-2.

What do the functional-status classes mean?

They are defined in ISO 16750 from A to E: A, all functions operate normally; B, a temporary deviation followed by a return to normal; C, function is interrupted and recovers on its own; D, recovery requires user intervention; E, permanent damage. The specification states the acceptable class for each test.