Molex Mini-Fit Jr 4-Pin Power Connector
4-pin rectangular connector
Standards: Molex Mini-Fit Jr series
What is the Mini-Fit Jr 4-Pin pinout?
The Molex Mini-Fit Jr 4-Pin Power Connector has 4 pins. Pin 1 is +12V (power). Pin 2 is GND (ground). Pin 3 is GND (ground). Pin 4 is +5V (power).
Standards: Molex Mini-Fit Jr series
Pin Assignment Table
| Pin | Signal | Type | Description |
|---|---|---|---|
| 1 | +12V | power | +12V DC (Yellow wire) |
| 2 | GND | ground | Ground (Black wire) |
| 3 | GND | ground | Ground (Black wire) |
| 4 | +5V | power | +5V DC (Red wire) |
Signal Types
Common Applications
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Map this connector into your BOM workflow →The Mini-Fit Jr 4-Pin connector has 4 pins: Pin 1 (+12V, 12V), Pin 2 (GND), Pin 3 (GND), and Pin 4 (+5V, 5V). Common in PC power supplies and ATX peripheral power.
Molex Mini-Fit Jr 4-Pin Pinout
The 4-pin Molex connector (officially Mini-Fit Jr) is ubiquitous in PC power supplies for peripheral power. It provides both +12V and +5V rails and has been used since the original IBM PC/AT.
Wiring Tips & Best Practices
Each pin can deliver 5-8A depending on wire gauge. Use 18 AWG minimum for high-current 12V applications. The connector is keyed with chamfered corners to prevent reverse insertion. Standard wire colors: Yellow (+12V), Black (Ground), Red (+5V).
Common Issues
Melted connectors from overloading (multiple SATA adapters daisy-chained). Loose pins from repeated insertion cycles. Never force the connector - if it doesn't slide in easily, check orientation and pin alignment.
Why Use Interactive Diagrams?
- Accuracy: Hover over pins to see exact signal names and descriptions
- Clarity: Color-coded by signal type (power, ground, data)
- Printable: Export clean diagrams for shop floor reference