Automotive wiring harness assembly precautions

Before the automotive wiring harness assembly, we must thoroughly familiarize ourselves with the circuit diagrams and wiring diagrams, understand the body electrical installation location and the specific structure of the body, and figure out the control mode of each division of labour to correctly connect the wires.

Below I talk about automotive wiring harness assembly considerations, I hope it will help you.

car wire harness
Car wire harness

1, Do not pull the harness too tightly during harness assembly (especially for horizontally arranged harnesses) to avoid driving the vehicle in an upside-down condition, which will cause the position of the harness fixing points to be misaligned, resulting in an instantaneous increase in the distance between the two fixing points, which will lengthen the harness resulting in the pulling off of the internal connectors of the harness/false connections, changes in the parameters of the wires, or even pulling off of the wires.

2, Automotive wiring harnesses should be assembled with sufficient clearance passages around them to keep them from being pressed by other parts and not tripped by other parts and their fasteners. Avoid extrusion, abrasion, or rupture of harness insulation due to faults such as grounding.

3, Do not arrange plugs of the same type and color nearby. Avoid inserting the wrong plugs during assembly to avoid damage to the wiring harness and appliances.

4, The plugs and connectors are arranged in a location that is easy to find and easy to operate with hands and tools. To facilitate inspection and maintenance, it is necessary to consider the length of the wires carried by the electrical parts according to the actual assembly situation. If the electrical parts are installed in the surface of the easy-to-operate position, you can save the wire directly connected to the components of the plug, if the electrical parts are installed in a more hidden location, and later maintenance and disassembly difficulties, according to the need to increase the length of the electrical parts of the wire with the appropriate length, so that the layout of the plug in the position for easy checking and maintenance.

5, The engine assembly after the plug should be very easy to connect, here mainly refers to the engine wiring harness and engine compartment wiring harness, engine controller ECU connection. As the engine is in a vibration state in the working condition, to make the engine wiring harness and cabin wiring harness, ECU connection is reliable, not only need to appropriately increase the length of the engine wiring harness (generally increase the length of not less than 50mm) but also need to increase the engine wiring harness end of the plug in front of the first 100mm or so to add a fixed point, will be fixed in the body to avoid the transmission of engine vibration, resulting in the plug in the loosening of the piece, The terminal should be connected falsely.

6, The wiring harness from the cab to the outdoor through the hole, the external wiring harness must be lower than the hole, to avoid dripping and spilling liquid on the harness, there is a possibility of entering the interior.

7, Four-door harness and cockpit harness connection, the door on the over-wire hole is lower than the body side enclosure on the over-wire hole. If there is liquid on the door harness rubber sleeve, it may only enter the door but not the cabin.

8, The plug and harness can be easily passed through the body of the over-wire holes, convenient assembly, saving installation time.

9, According to the installation depth of the electrical device, the location of the socket, the direction of the socket opening, and the rear space after the assembly of the electrical parts, by the ease of operation, the appropriate increase in the length of the wiring harness on the connector reserved.

10, The reserved length of the four-door switch harness and the reserved length of the connector of the overhead light and switch harness on the interior ceiling are also calculated concerning the calculation method of the electrical device installed at the instrument panel.

11, It is necessary to consider that in the direction of the plug-in connector, there must be a space greater than twice the length of the plug in the direction of the plug.

12, The length of the audio antenna wiring harness to determine the same needs to consider the assembly of sufficient length reserved.

13, Other plug harness connectors, consider the need to reserve the length of the harness to facilitate disassembly. For electrical parts installed in the surface position, installed in the seat under the (flip seat can be operated under the payment instrument panel (remove the payment instrument panel can be operated) or two harness assembly plugs, etc., may not be reserved length, concerning the actual results of measurements and plug parameter design.

14, Car wiring harness can not be excessively bent, wire joints can not be affected by oil, water, debris, mud, etc., and unused wire should be wrapped with tape to avoid short circuits.


When assembling automotive wiring harnesses, it is important to avoid excessive bending of the wires and ensure that wire joints are not affected by oil, water, debris, or mud. Unused wires should be wrapped with tape to prevent short circuits. These precautions are necessary to ensure the proper functioning and safety of the car’s electrical system.