Practical cable assembly guide
Cable Assembly Pinout & Connector Viewing Direction
A pinout says which contact at one end connects to which contact at the other. A viewing direction tells the reader which side of the connector they are looking at. Record both so a change of viewpoint does not become a wiring mistake.
No finished drawing? Start with what you have. Photos and a short description are welcome.
Same End A, opposite views
Keep the top marker up. Turn the same connector 180° around its vertical axis to look at the other face. The top marker is an orientation reference, not a pin-1 mark.
End A · Mating face
Mating face: left to right 1 → 2 → 3 → 4. Only the viewing direction changes; cavity numbers stay attached to the same cavities.
Same connector. Different viewpoint.
The mating face is the side that meets the other connector. The wire-entry face is the side where the wires enter the housing. Here, both views show the same End A—not the two ends of a cable.
In this single-row example, looking from the opposite side with the top reference kept up reverses the left-to-right positions. Cavity 1 is still cavity 1; it has not become cavity 4. Rotating the connector another way changes the view again.
These drawings teach the viewpoint only. They are not JST, Molex or any other manufacturer's cavity-numbering drawings. Use the exact part drawing and readable housing markings to identify the real cavity numbers.
Three things that make a pinout clear
- 01
Name both ends
Call them End A and End B. Add the connector reference if known. For branches, use End C, End D and so on. Do not use the same end label twice.
- 02
Label the view and reference
Write “mating-face view” or “wire-entry view” beside each view. Mark a latch, key or other orientation reference and identify cavity 1 from the correct drawing or clear markings—not from wire color alone.
- 03
List each connection
Write entries such as A1 → B1 and A2 → B3. Record intentionally empty cavities, splices and shield/drain connections separately when applicable. Mark unknown details “to confirm” instead of guessing.
A connection table removes the guesswork
Compare two illustrative four-wire mappings below. Only the connections for cavities 1 and 2 change. The table and diagram update together.
Trace each wire from End A to End B
The two columns are cavity-ID lists, not connector-face views. Select an example to compare the connections.
One-to-one example: each End A cavity connects to the same-numbered End B cavity.
| End A | Wire ID | End B |
|---|---|---|
| 1 | W1 | 1 |
| 2 | W2 | 2 |
| 3 | W3 | 3 |
| 4 | W4 | 4 |
Specify the actual A-to-B pairs instead of relying on “straight”, “reversed” or a wire's position in a photo. Lines crossing on a page do not, by themselves, mean the wires are electrically joined.
Manufacturer example: Samtec's assembly options (PDF) distinguish connection pairs as well as physical orientation. This is a terminology reference, not a specification for these illustrative diagrams.
What to send if you only have a cable or a photo
You do not need to complete a technical form before contacting us. Send whichever items you already have; we can help identify what still needs confirmation.
- A clear photo of each connector's mating face, plus a wire-entry or side view showing the latch/key and any readable markings.
- A sketch or a few A-to-B connections, if known. A photo alone may not reveal how a covered cable is wired inside.
- Approximate length, quantity and what the cable connects. Say which details are not yet decided.
Confirm the mapping before the sample becomes the reference
Zeakka is a trading and sourcing partner. We coordinate drawing questions, suitable factories and samples. Before making the agreed sample, confirm the two end references, viewing directions and connection table together. Keep the revision with any approved sample so repeat orders use the same reference.
Each harness is checked for continuity and short circuits against the agreed connection requirements. A pass against the wrong reference does not make the pinout correct for your equipment. Equipment function, polarity and application-specific performance still need the appropriate checks.
For testing limitations, see Cirris: Guidelines for Testing Components. This reference does not describe Zeakka's test equipment.
Pinout questions
Is pin 1 always on the left?
No. Its apparent position depends on the connector, the viewing direction and how the connector is oriented. Check the exact part drawing and readable cavity markings. Do not copy numbering from another family or assume that male and female parts use the same left-to-right view.
Can matching wire colors confirm the pinout?
Not on their own. Colors help identify conductors only when their connections are documented. A red wire is not proof of a particular cavity or polarity. Use the confirmed connection table and appropriate checks on an unpowered, disconnected assembly.
Does “straight-through” always mean A1 connects to B1?
Do not rely on that phrase alone. Layout and assembly-option terminology can differ. State every required pair, such as A1 → B1, and identify the view at both ends so the supplier does not need to interpret the description.
Can I ask for a quote without a pinout drawing?
Yes. Send photos, a sketch or a description, plus the quantity if known. We can review the available information and flag what needs confirmation. The required connections must be agreed before the assembly is made; you do not need every detail ready for the first conversation.
Have a cable to identify or a connection to clarify?
Send what you know. We will help separate confirmed details from the questions that need an answer.