What are these plastic connectors? They’re female and male counterparts. One has male pins and the other has female metal square-holed pin receptacles. What are these called? Here’s a side view and into-pin view. The wires are 20 AWG. They're for connecting to the solar panel and DC motor of a solar-powered attic fan. I want to make another pair. How do I crimp the wires into the pins and insert them into the connectors? What is the specific crimper called?

Side view

View into pins

  • 1
    Upvote for including photos and making this a quality question. I'd expect you will get quality answers from this. I have seen these inside microwave ovens, but nowhere else. Welcome to Home Improvement. Take the tour at diy.stackexchange.com/Tour to get the most out of this site.
    – SDsolar
    Jun 4, 2017 at 23:27
  • @SDsolar , +1, the tour was helpful and it just gave me an achievement.
    – CodeBricks
    Jun 5, 2017 at 8:38

2 Answers 2


I have always referred to them as "Molex Connectors". They are assembled by crimping the individual pins and inserting them into the plastic connector. The pins are crimped by a special tool. Using a generic crimping tool will result in a poor connection. A small tube shaped tool is used to remove the pins from the plastic connector. Unless you plan on doing many of these connections the cost of the tools makes it an expensive repair. A less expensive solution is to purchase the connectors with a pigtail (a short section of wire factory installed). Then make the connection with a generic crimped connector available at most automotive parts stores.

  • I always soldered instead of crimping. No special tool needed. Jun 4, 2017 at 22:32
  • +1, thanks for pointing me in the right direction & for pigtails advice. Do you mean to splice & solder pigtail’s tail end to the source & then plug the pigtail’s factory-installed connector (head end) to the one in my pic? Molex is a company/brand. What are the generic versions (if any) called? From your answer, I found everything except the pigtail that comes with the connector. Do you know what the pigtail is called specifically? If you have time, please see the end of my answer that has the other components’ names, if that narrows down the search terms (not trying to hijack your answer).
    – CodeBricks
    Jun 5, 2017 at 10:02
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    The easiest solution might be to find a 2 pin 20gauge male and female connectors. Cut off both your factory connectors. Then splice them to your wires. You can solder or use generic butt connectors available at an auto parts supplier.
    – mikes
    Jun 5, 2017 at 10:58

As mikes answered, these connectors are a type of Molex connector. (Or they may be their generic equivalents, if any.) Molex is a company/brand. It has several types of 2-pin connectors. The connectors in my OP pictures are part of either Molex’s “Mini-Fit Jr.” trademark of power connectors or a generic equivalent (if any; I don’t know whether generics are permitted to be made).

Molex’s Mini-Fit Jr. diagrams considers the plastic connector that gets partially enclosed in its counterpart connector when mated as the receptacle, perhaps because the receptacle permanently houses the socket (female) terminals. Molex considers the plastic connector that partially encloses its counterpart connector when mated as the plug, perhaps because the plug permanently houses the pin (male) terminals.

I don’t know what the connectors in my OP question are called if unbranded, so I’d also appreciate an answer that can give unbranded but specific names or search-friendlier branded names. This question discusses the difficulty in web-searching for Molex and generic or other-brand connectors, the shortcomings of related nomenclature, and the usefulness if the nomenclature were to have some basis in chamfered keying permutation, and it lists a few brands. In web searches, the Molex items can almost only be disambiguated by their manufacturer model numbers. Without first knowing the number or uniquely identifying unbranded terms, some trial-and-error options are image searches or searches on manufacturer or retailer sites with specific categories. Waytek has the category:

Terminals & Connectors > Multi-Pin Connectors > Mini Fit JR Connectors.

It’s difficult to find these connectors on Molex’s website even with the model numbers, because it gives overly-generalized reference pictures, sometimes with a different number of circuits (i.e. corresponding pins or wires), of the model’s containing series. Waytek gives more specific pictures. (I’m not affiliated with any party, but this is how I best found the info in the absence of clearer nomenclature.) There are several models of Mini-Fit Jr. connectors. Going by Waytek’s nomenclature, the items in my OP question appear to be the following or their generics (if any):

The plug is Molex 39-01-2021 Mini-Fit Jr. Connector, 2-Pin Panel Mount Plug.

The receptacle is Molex 39-01-2020 Mini-Fit Jr. Connector, 2-Pin Receptacle.

The pin terminal is Molex 39-00-0041 Mini-Fit Jr. Pin Terminal, 24-18 AWG.

The socket terminal is Molex 39-00-0039 Mini-Fit Jr. Socket Terminal, 24-18 AWG.

Their corresponding extraction tool is Molex 11-03-0044 Mini-Fit Jr. Extraction Tool.

The only crimp tool I found named by Waytek specifically for Mini-Fit Jr. is Molex 63819-0900 Mini-Fit Jr. Crimp Tool, which is expensive. Molex’s corresponding Application Tooling Specification Sheet lists the aforementioned terminals’ model numbers as compatible.

A cheaper crimper, named by Waytek but not specifically for Mini-Fit Jr., called the Molex 63811-1000 MLX Hand Crimping Tool, 24-14 AWG, applies to the desired gauges, but the corresponding Molex Application Tooling Specification Sheet doesn’t specify the aforementioned terminals. But the “Application Tooling” section on the righthand side of Molex’s product page lists some models of terminals that seem to have pins shaped similarly to the desired one. Also, the corresponding Amazon listing includes the phrase “For Mini-Fit Jr.” in its title.

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