Automotive Wire Harness Open‑Short Simulator

1. Basic Understanding of Equipment

1.1 Model Classification

LISUN Model	LIS-LSCS-1730	LIS-LSCS-1750
Number of Switches	Route 30	Route 50
Maximum Voltage	60 VDC/220 VAC
Maximum Current	10 A per channel, 50 A maximum for the entire unit
On/Off Switches (S1)	<20 mΩ/10 A
Short-Circuit Switches (S2/S3)	<20 mΩ/10 A
Power Switches (S4/S5)	<5 mΩ/50 A
Open-Circuit/Short-Circuit Trip Time	20 ms–10000 s
Number of cycles	1–10000 times
Number of Test Steps	Steps 1–255
Feature Configuration	Full touchscreen, built-in standard library, voltage and current monitoring
Control System	10.1-inch Android Capacitive Touchscreen Display with Chinese and English Support
Operating Environment	Temperature: 10–40°C; Humidity: 30%–70%
Dimensions	460 × 180 × 550 mm
Weight	About 8 kg

1.2 Compliance with Reference Standards

This equipment’s testing capabilities fully cover the requirements of the following international standards, national standards, and corporate standards of major automakers, and can be used directly for compliance testing under the corresponding provisions.

1.2.1 International and National Standards

Standard Number and Section	Standard Title	Corresponding Test Items
GB/T 45120-2024, Clause 10.15	Road Vehicles—Electrical Requirements and Tests for 48-V Power Supplies: Short Circuits in Signal Lines and Load Circuits	48V System Signal Line/Load Circuit Short-Circuit Test
GB/T 28046.2-2011, Clauses 4.9 and 4.10	Environmental Conditions and Tests for Electrical and Electronic Equipment in Road Vehicles—Part 2: Electrical Loads	Open-Circuit Test / Short-Circuit Protection Test
ISO 16750-2:2023, Clauses 4.9 and 4.10	Road Vehicles—Environmental Conditions and Testing for Electrical and Electronic Equipment—Part 2: Electrical Loads	Open-Circuit Test / Short-Circuit and Overload Protection Test

1.2.2 Corporate Standards of Major Automakers

Standard Number and Section	Standard Title	Corresponding Test Items
JA 3700-MH-4-2021/2025, Section 4.20	FAW Group Passenger Vehicle Electronic and Electrical Components: Electrical Environmental Specifications	Short-Circuit Test
QLP YSY 0231-2024, Section 16.17	Zhejiang Leapmotor Technology Co., Ltd. Corporate Standards	Short-Circuit Protection Testing for Signal Lines and Load Circuits
QSK J07.362-2024, Sections 5.17/5.20	Electrical Test Methods for Saelis Electrical and Electronic Components and Subsystems	Connector Disconnection Test / Short-Circuit Test of Signal and Load Circuits
SMTC 3 800 001, Section 5.16	SAIC Group General Testing Requirements for Electronic and Electrical Components	Short-Circuit Protection Testing for Signal Lines and Driver Circuits
VW 80000:2021/2022 E-17/E-20	Test Specifications for Electrical Units in Vehicles Weighing Up to 3.5 metric tons	Signal and Load Circuit Short-Circuit Test / Reverse Power Feed-Through Test
VDS 28401-02 [4]:2025, Section 6.1.5	Dongfeng Nissan General EMC Test Standard for E& E Components on the Test Bench: EQ/TE05	Input/Output Port Short-Circuit Test to Power and Ground

1.3 Application Scenarios

The LIS-LSCS Series Automotive Wire Harness Open‑Short Simulator is a specialized testing device designed for automotive electronic and electrical testing and R& D. It can simulate standard test conditions—such as open circuits, short circuits, short circuits to the power supply, short circuits to ground, and connector disconnections—on signal lines and load circuits, meeting the stringent testing requirements for wiring harness reliability and protection performance set forth by GB national standards, ISO international standards, as well as the stringent testing requirements of major automakers regarding wiring reliability and protection performance. The equipment supports independent or synchronized control of multiple channels, allowing all tests to be completed with a single wiring setup, which significantly simplifies manual operations and improves testing efficiency and consistency.

1.3.1 Applicable Industries and Scenarios

Automotive OEMs: DV/PV validation of components, incoming quality sampling inspections, and electrical reliability testing; Automotive parts manufacturers: Factory-level reliability testing of wiring harnesses, controllers, and sensors; Third-party testing organizations: Automotive electronics compliance certification and standards conformity testing; Research and education: R& D in automotive electronics technology, as well as teaching and experimental demonstrations.

1.3.2 Test Subjects

Complete low-voltage wiring harness assemblies and local wiring harness subsystems; input and output ports for various automotive controllers (BCM, ECU, VCU, BMS, etc.); wiring harnesses for in-vehicle sensors and actuators; and wiring harnesses for external components such as body electronics and in-vehicle entertainment systems.

2. Precautions for Use

2.1 Environmental Requirements

Ambient temperature: 23 °C ± 5 °C; relative humidity: 45–75%, non-condensing; altitude: ≤2000 m; no strong vibrations or electromagnetic interference in the vicinity; the equipment must not be used in dusty or flammable and explosive environments.

2.2 Power Supply Requirements

Input power supply: AC 220 V ±10%, 50 Hz; Input power: ≤1 kW; The power supply must be properly grounded, with a grounding resistance of ≤1 Ω; It is recommended to use a voltage regulator to prevent power grid fluctuations from affecting test accuracy.

2.3 Wiring Principles

Use power cables with the specified wire gauge to prevent overheating under high current conditions; keep test cables as short as possible and route them in parallel to minimize the impact of parasitic parameters; ensure that the DUT (Device Under Test) enclosure is reliably connected to the equipment’s protective ground; and route signal and power cables separately to avoid cross-interference.

2.4 Operational Safety Guidelines

Wear appropriate insulated protective gear; before testing, ensure that all connections are secure and that there are no exposed conductors; do not touch or connect/disconnect wiring harnesses or cables during testing; if you hear unusual noises, smell an unusual odor, or notice smoke, disconnect the power immediately; when conducting prolonged continuous testing, ensure adequate ventilation and heat dissipation for the equipment.

3. Equipment Overview and Wiring

3.1 Front Panel

See Figure 3-1.

Number	Note
①	Device power Switches: Press briefly to turn on, press and hold to turn off.
②	10.1-inch Capacitive Touchscreen
③	USB1 port: Used by LISUN engineers for device debugging; users do not need to use it
④	USB 2.0 port, which can be used to connect a mouse to control the touchscreen, or to connect a USB flash drive to upgrade the software or update database files

3.2 Back Panel

See Figure 3-2.

Number	Note
①	Power cord receptacle and fuse; ensure the input power supply is properly grounded
②	Circuit breaker, main power switch for the input power supply for equipment
③	Protective grounding terminal: If the input power supply does not have a reliable ground connection, this terminal must be connected separately to ground.
④	DUT Power Input Connector: A suitable external power supply must be provided for the DUT. You may use LISUN’s LIS-APS series four-quadrant power supply, or another suitable DC regulated power supply appropriate for the DUT. Pay attention to polarity.
⑤	DUT power output connector; connect the DUT power cord here. Observe the polarity.
⑥	DUT Power Switches
⑦	Signal wire harnesses for continuity, short circuit, and connection testing; 30/50 channels total
⑧	RS485 interface/LAN port, which can be connected to a computer to use the host software (for backup purposes). The host software offers the same functionality as the touchscreen; please contact us if needed.

3.3 Introduction to Accessories

See Figure 3-3.

Number	Note
①	Power Cord
②	Ground Wire
③	Signal Line Connection Module
④	DUT Power Supply Input and Output Cables
⑤	Ethernet cable, used to connect a computer to host software

See Figures 3-4 for a schematic diagram of the external power supply and DUT connections:

See Figures 3-4 for a schematic diagram of the external power supply and DUT connections:

4. Introduction to the Touchscreen Program

4.1 Test Interface

See Figure 4-1.

Number	Note
①	Equipment Main Circuit Schematic
②	Select the channel you want to test
③	Click to run the device’s built-in standard tests, or select a custom test
④	If you select the device’s built-in standards, all test parameters in the red-bordered areas have already been configured according to the corresponding standards and do not need to be modified; if you select “Custom Test,” you can modify the test parameters.
⑤	For custom tests, you can save the configured test parameters to the device so they can be recalled later.
⑥	Runtime is displayed and calculated automatically; a progress bar will appear to show the test progress once the test begins.
⑦	Switches for S1 through S5 have already been configured in the test parameters. However, if you need certain Switches to remain normally open during the test, you can manually click to close Switches corresponding switch before the test begins, ensuring it remains in the normally open state throughout the test.
⑧	RUN: Once you have selected the waveform and other parameters, click this button to start the test. During the test, the progress bar updates once per second to show the current progress until the test is complete. Click this button again during the test to stop the current test.
⑨	Display the DUT’s current voltage and current

Test Parameter Overview: a) Add, delete, or reset test steps; Switches Switch status settings; c) Test duration; Switches: simultaneous or individual; e) Run mode: manual or automatic (in automatic mode, the system automatically proceeds to the next test step once the current one is completed); f) Number of cycles.

4.2 Database File Interface

See Figure 4-2.

Number	Note
①	Test Plan Standard Library Management. You can manage the custom test parameters you have saved; please do not modify or delete the test parameters built into the device.
②	If you have other standard tests but do not wish to create custom tests, please contact us and send us the details of the relevant standards. We will guide you through the process of updating the database file with those standards directly using a USB drive.

4.3 Settings Interface

See Figure 4-3.

Number	Note
①	Switch Between Chinese and English
②	Communication settings are set to “LOCAL” by default. If you need to use host computer software, you can switch to the RS485 or LAN port. Please contact us.
③	Volume Settings

4.4 About the Interface

For device information, firmware version, and copyright notice, see Figure 4-4.

5. Procedures for Conducting Continuity and Short-Circuit Tests on Automotive Wiring Harnesses

5.1 General Operating Procedures

5.1.1 Wiring

Ensure that both the device and the DUT are powered off; use a test cable to connect the device’s DUT power output port to the DUT’s power cord; Use a cable to connect an external power supply (LIS-APS or other regulated DC power supply) to the DUT input power supply connector on the rear panel of the device; connect the DUT signal cables to the signal cable channels on the rear panel of the device using the dedicated terminals.

5.1.2 Parameter Settings

Set the test parameters as described in Section 4.1, and select the channels you want to test.

5.1.3 Test Execution Steps

Turn on the external power supply and connect it to the DUT; turn Switches on the back of the device and verify that the DUT is operating normally; on the touchscreen test interface, click the RUN button to start the test; observe the DUT’s operating status and record any observations; wait for the test to complete; in case of an emergency, you may press the stop button to halt the test immediately.

5.2 Typical Standard Test Conditions and Criteria for Acceptance

5.2.1 Open-Circuit Test (Corresponding to GB/T 28046.2, Section 4.9 / ISO 16750-2, Section 4.9)

Test Objective: To verify the DUT’s functional behavior under open-circuit faults in signal and load lines, as well as its ability to recover after the fault is cleared.

Pass/Fail Criteria: Grade A: All functions operate completely normally during and after testing, with no performance degradation; Grade B: Acceptable temporary degradation occurs during testing; functionality automatically recovers after the fault is resolved; Grade C: Functionality fails during testing but can be restored through manual reset or reboot, with no hardware damage; Grade D: Permanent hardware damage occurs and functionality cannot be restored; the unit is deemed to have failed the test.

The specific qualification levels are subject to the product’s technical specifications; key functions typically require a Grade B or higher.

5.2.2 Short-Circuit Protection Test (Corresponding to GB/T 28046.2, Clause 4.10 / ISO 16750-2, Clause 4.10)

Test Objective: To verify the DUT’s ability to protect against short circuits between its ports and the positive power supply terminal or ground, ensuring there is no permanent damage or safety risk.

Acceptance Criteria: During testing, the protective mechanism triggered normally, with no smoke, fire, or melting of the housing; after testing, there was no permanent hardware damage, and functionality met the specified grade requirements; the protective device operated as designed, with no secondary failures; and the protective function remained effective upon retesting.

5.2.3 Short-Circuit Test for Signal Lines and Load Circuits in the 48V System (in accordance with GB/T 45120-2024, Clause 10.15)

Test Objective: To verify the short-circuit protection performance of signal lines and load circuits for components in a 48V power supply system.

Requirements: A short circuit must not cause safety risks such as fire or loss of control; the protective circuit must operate reliably, and functionality must be restored after the fault is cleared; the low-voltage control section must not be affected by a short circuit and must maintain its basic functionality.

5.2.4 Connector Disconnection Test (in accordance with QSK J07.362-2024, Section 5.17, and other automotive industry standards)

Test Objective: To simulate transient connector contact failures caused by vibration and verify the DUT’s immunity to interference and fault tolerance.

Acceptance Criteria: No system crashes, unexpected resets, or data loss may occur during testing; communication signals must not experience irrecoverable communication interruptions; after testing, all functions must operate normally, with no hidden damage.

5.3 Procedures at the End of the Test

Ensure that both the equipment and the DUT are powered off; disconnect the connections on the DUT side first, then disconnect the connections on the equipment side.

6. Daily Maintenance and Care of Equipment

6.1 Daily Cleaning

6.1.1 Cleaning Schedule and Procedures

After each use: Clean the touchscreen surface and remove dust from the device panel;

Weekly: Clean the equipment housing and the filters in the vents;

Monthly: Clean dust from inside the equipment (to be performed by a professional).

6.1.2 Cleaning Methods

Wipe the exterior with a clean, soft, lint-free cloth; use a special screen cleaner for the touchscreen; clean the ventilation openings with a soft-bristled brush and a vacuum cleaner if necessary; do not use corrosive solvents such as acetone.

6.2 Periodic Inspections

Check the power cord for damage or wear; check that the ground connection is secure; check that the fan is operating normally; check that the buttons and touchscreen are responsive; check the terminal blocks for oxidation or loose connections.

6.3 Storage and Handling

6.3.1 Requirements for Long-Term Storage

Storage Conditions: Temperature -10°C to +50°C, humidity ≤85%; Clean the equipment and apply dust protection before storage; Power on the equipment once every 3 months, running it for at least 30 minutes each time; Avoid stacking or applying heavy pressure to prevent panel deformation.

6.3.2 Precautions for Handling

Unplug all external cables before moving the device; use the original packaging and ensure it is properly cushioned and protected; keep the device upright during transport and avoid harsh vibrations; when lifting, grip the bottom and both sides of the device—do not lift by the panel.

6.4 Calibration Interval Requirements

To ensure the measurement accuracy and operational reliability of the equipment, it is recommended that it be sent periodically to a qualified third-party metrology laboratory for calibration. The recommended calibration interval is 12 months. The specific calibration interval may be determined by the user based on frequency of use, environmental conditions, and quality system requirements.

7. Troubleshooting and Resolving Common Problems

Fault Symptoms	Possible Causes	Procedure
The device won’t turn on	The input power supply main power switch on the back is not turned on, or the fuse has blown.	Turn on the input power supply switch located at the power cord receptacle on the back of the device; check the fuse, and if it has blown, replace it with a fuse of the same rating.
Touchscreen Malfunction After Power-On	System freeze, loose ribbon cable	If the problem persists after restarting, disconnect the power, remove the device’s outer casing, and check whether the touchscreen ribbon cable is loose.
Test Stopped Automatically Midway Through	Over-temperature protection triggered, overcurrent/overvoltage protection triggered, external power interruption	Check whether the equipment’s ventilation is obstructed or whether the ambient temperature is too high; check the DUT for short circuits or overloads; check whether the external power supply has stopped outputting power.
USB Flash Drive Not Recognized	USB drive format is incompatible or capacity is too large	Use a FAT32-formatted USB drive with a capacity of no more than 32 GB; if that doesn’t work, try a different USB drive.