Power flows accurately when each link is correct. Songchuan wire harnesses do the exact task for your projects.

A Songchuan wire harness connects Song Chuan relays to the other links of your system in a single location, ready to fit the unit. Wires, terminals, sockets, fuses, and protective sleeves are assembled as a single unit for this system. Without it, the whole system will be messy, and there will be many issues. You can save time and money with this harness. Song Chuan relays are trusted for steady switching in cars, machines, and home appliances. Our harnesses are made with the best-quality selected materials that ensure the highest cable quality. We build the harnesses accurately according to your plan, so you get the best product.
Our core series covers three product lines, each built for a different need. Choose a standard relay, a complete relay harness, or a fully custom design made for your project.

Song Chuan is a well known relay maker. Its relays handle high current in a compact package, making them a smart pick for tight spaces. We source genuine Song Chuan relays so you get the performance the brand is known for. Our range covers automotive relays, PCB relays, and compact micro relays. Each type comes in different coil voltages and contact forms to suit your circuit. We verify part numbers and batch details before adding any relay to a Songchuan wire harness. This keeps fake or mixed parts out of your supply chain. You can buy relays individually or as part of a complete Songchuan relay wiring harness set.

A relay works only as well as the wiring around it. That is why we build each Song Chuan automotive relay harness as one complete system. The relay, socket, wires, fuse, and connectors are matched to carry the right load. We crimp every terminal with calibrated tools and check the pull force on each one. Wires are cut to exact length, so there is no extra slack to rub or tangle. Each harness is labeled for fast, error free fitting on your line. This design works well for headlights, fans, pumps, horns, and control boxes. You get a plug-and-play unit that saves labor and reduces field failures.

Some projects need more than a catalog part. Our team designs non-standard harnesses tailored to your exact layout and load requirements. Send us a drawing, a sample, or even a rough sketch, and we will turn it into a working design. We can add extra relays, diodes, fuses, or sensors to one assembly. Special jackets, heat-resistant sleeves, and waterproof seals are all available. We also match odd lengths, rare connectors, and custom color codes. Each Songshun custom wire harness is proven with a sample before full production starts. This way, you only pay for a design that fits and works from day one.
A harness is a small part with a big job. If it fails, the whole machine can stop. Our Songchuan harnesses are built to prevent that with smart design and careful work. Here is what sets them apart.

Every harness follows the original Song Chuan relay specs. Pin layouts, socket sizes, and terminal types all match the relay maker's data. This means the harness drops into your system with no rework. Each Songchuan relay socket connector securely holds the relay and keeps the contacts clean. You can replace old wiring or build new systems with full confidence.
Clean signals and steady power keep your system running right. We choose wire gauges that carry your load with low heat and low loss. Shielded cables and twisted pairs are available to block electrical noise. Firm crimps stop loose contacts that cause flicker or dropouts. The result is steady power, clear signals, and long service life.
Excellent harnesses start with good hands and good tools. Our team uses calibrated crimp machines and checks each terminal by cross-section. Wires are bundled neatly with tape, sleeves, or conduit to guard against wear. Stress points get extra protection where cables bend or rub. Each harness is built to last through heat, shaking, and years of use.
We select RoHS- and REACH-compliant wires, terminals, and housings. For markets that ask for it, we use UL-recognized wire and parts. This helps your products meet export rules in the US, Europe, and Asia. Material records are kept for each order for easy tracing. Your harness is safe for people, the planet, and your paperwork.
Every project is different, and our process is built for that. Our engineers review your drawing and reply with clear questions and a quote. Small sample runs help you test fit and function before you commit. Large orders move to production with the same tested setup. You get quick answers, clear updates, and on-time delivery.
No two machines are wired the same way. Because of this, we approach each and every custom harness as if it were its own individual project. Our first step is to become familiar with your load, space, and operating conditions. Following that, we select the appropriate Song Chuan relay, wire size, and connectors for the task at hand. In order to get your permission, our engineers will draw the layout and then share it with you. Before beginning any bulk order, a sample is constructed and put through its paces. After you have given your approval, each and every device will be manufactured to that particular specification. For the purpose of testing, we support low-volume builds, and for mass manufacturing, we support high-volume runs. Listed below are the several industries that make the most frequent use of our bespoke harnesses.

Factory machines run long hours and face constant vibration. Our harnesses for automation gear are built to handle that daily stress. We use oil-resistant jackets and strong strain relief at every joint. Relays control motors, valves, conveyors, and safety circuits with steady switching. Clear labels make installation and repairs faster for your technicians. The result is less downtime and a smoother production line.

Medical and lab devices need clean power and exact signals. Our harnesses for this field focus on low noise and tight quality checks. Each Songchuan PCB relay connector is carefully fitted for a secure board connection. Shielded wires help protect sensitive readings from interference. We keep full records of materials and tests for each batch. This gives your team the traceability that precision work demands.

Solar systems, battery packs, and EV chargers carry heavy loads for long periods. Our new energy harnesses are made with high-temperature wire and strong terminals. Relays switch power safely between panels, batteries, and inverters. UV-resistant jackets protect outdoor runs from sun damage. Sealed connectors keep out dust and rain. These harnesses help your green energy systems run safely for years.

Cars and trucks are exposed to heat, cold, water, and shaking. Our automotive harnesses are built to withstand it all. Each Songchuan automotive wiring assembly links relays to lights, fans, pumps, and starters. Waterproof seals and fuse holders guard every circuit. Wires are routed and secured to prevent rubbing against sharp edges. You get a harness that fits right and works every time the key turns.
Before it is shipped out of our plant, each Songchuan wire harness is subjected to a full series of rigorous quality and performance checks. If the harness passes all required factory tests then we safely deliver it.

The process of quality begins well before assembly. Wires, terminals, and housings are only purchased from reputable vendors when we make purchases. On each and every batch that is received, the size, finish, and markings are examined. Copper wire is examined to ensure that it is pure and has the appropriate number of strands. Every plastic component is examined for cracks, warping, and flame rating before being used. Materials are only allowed to proceed forward with production if they pass these inspections.

Harnesses are frequently used in environments that are either extremely hot or extremely cold. In order to simulate your actual operating range, we conduct tests on samples in a climate chamber. This may span temperature ranges ranging from -40 degrees Celsius to 125 degrees Celsius for engine bay components. Following each cycle, we inspect the terminals for any signs of cracking, shrinking, or looseness. Insulation must maintain its range of motion, while contacts must continue to be strong and reliable.

A number of inspections are performed on every finished harness before it is packed away. A continuity test verifies that each wire is connected to the most appropriate pin. Tests of insulation look for any leaks or short circuits in the system. The purpose of pull tests is to ensure that terminals remain stable when subjected to force. Damage, incorrect labels, or improper packaging are all caught via visual inspections. There is no shipment until each stage has been completed.

Our Songchuan wire harnesses power headlights, cooling fans, fuel pumps, and horns. They are built to handle engine heat and road shock. Each one fits cleanly into both new builds and repair work.

Factory lines rely on relays to start motors and control valves. Our harnesses keep those signals steady through long shifts. Strong jackets protect them from oil, dust, and wear.

Washers, air conditioners, and ovens use relays to switch power safely. Our harnesses are compact and sized for tight spaces. They help appliance makers speed up assembly and cut errors.

Solar, battery storage, and EV charging units handle high current. Our harnesses use heat-resistant wire and sealed connectors. They keep power flowing safely in both indoor and outdoor settings.

Alarm panels, access control systems, and network boxes require reliable switching. Each Song Chuan micro relay harness connector saves space in small housings. Clean routing makes service quick and simple.
We source them only through trusted channels. Our team checks batch details and markings on every delivery. This keeps fake parts out of your supply chain and gives you relays that switch reliably.
We use oxygen-free or high-purity copper for every conductor. Pure copper conducts current with low resistance, so less energy is converted into heat. This keeps the harness cooler and maintains steady power delivery under load.
Each terminal carries a layer of tin plating over the base metal. The tin resists rust, even in damp or humid conditions. This helps the terminal hold a strong, clean contact and avoid weak connections over time.
We choose the wire jacket based on how your harness will work. PVC suits general use, XLPE handles heat and oil, and silicone stays soft for repeated flexing. The right match helps the wire last longer.
Our connector housings are made from tough, flame-rated nylon. The material holds each terminal firmly in place, so pins stay aligned under vibration. It also resists impact and heat in demanding settings.
We apply heat-shrink tubing over splices, joints, and bend points. When heated, it shrinks tightly around the wire, forming a snug protective layer. This guards against wear, moisture, and strain where wires often fail.
Rubber seals and grommets sit wherever wires enter a housing or pass through a panel. They block water, dust, and dirt from getting inside. They also cushion the wire against sharp edges to prevent cuts and chafing.
For rough or moving areas, we add corrugated conduit or braided sleeving. These layers protect wires from abrasion, impact, and hot surfaces. They also keep wires neatly bundled for easier installation.

Every wire naturally resists current a little, which slightly lowers the voltage at the connected load. Too much drop can make relays chatter, lights dim, and motors run weak.
Voltage drop equals current times circuit resistance (V=I×R). Resistance increases with wire length and decreases with the actual cross-sectional size of any conducting wire in an electrical system.
Current travels out on one wire and back on another. We use the full round-trip length of the circuit, not just the one-way run of the single physical wire from one terminal to another terminal.
Many 12V and 24V electrical circuits aim to keep the voltage drop under roughly about 3%. We set this specific limit carefully based on your actual load and your own unique project specification.
If the voltage drop across the cable line is too high, we move to a thicker wire. This keeps operating voltage stable without adding needless extra weight or extra manufacturing cost.
After calculation, we measure the voltage drop on a sample harness under test load. This confirms the design matches the required numbers.
Copper resistance increases as temperature rises. We factor in real-world operating heat so the harness performs in the field, not just on paper.
The relay harness fit our fan control box on the first try. The crimps were clean and every wire was labeled. It saved our team hours on assembly.

We needed a custom layout with three relays and a fuse block. QL-Custom reviewed our drawing and suggested a better wire size. The final product works perfectly.

Quality is very consistent from batch to batch. We have used these Songchuan wire harnesses in our machines for a long time with no field failures. Communication is always quick.

The sample arrived fast, and the team made small changes without any fuss. Bulk production matched the sample exactly. I am very happy with the service.

Their voltage drop check caught a problem in our original design. The thicker wire they suggested fixed the relay chatter we had. That kind of detail matters.

Clear quote, clear drawing, and on-time delivery. The Song Chuan relays were genuine and well matched to our load. We will order again for our next project.


When your equipment depends on relays, the wiring behind them must be flawless. QL-Custom Technology Ltd. combines genuine Song Chuan relays, high-quality materials, and skilled engineering in every Songchuan wire harness we build. Our team reviews your drawing, calculates voltage drop, tests samples, and checks each finished unit before it ships. We handle small prototype orders and large production runs with the same care. You get fast quotes, clear communication, and a harness that fits right the first time. Whether you build cars, machines, appliances, or energy systems, we are ready to support your next project. Send us your drawing today and get a custom Songchuan wire harness quote from our engineering team.