0039012040
Molex · Connectors · Mini-Fit Jr receptacle housing, 4 circuits, 4.20 mm pitch · Wire-to-board (mates with 5566/5569 headers)
Profile 0039012040 Profiled: 23 Sep 2026
Lifecycle: Active
Availability risk: Low
Specification
Transcribed from the manufacturer datasheet
| Pitch | 4.20 mm |
|---|---|
| Circuits | 4 |
| Current rating | 9 A per circuit with 18 AWG wire |
| Voltage rating | 600 V AC/DC |
| Contact resistance | 10 mΩ max |
| Mating cycles | 30 |
| Tolerance | Pitch ±0.1 mm; housing height ±0.3 mm |
| Voltage rating | 600 V AC/DC, 9 A per circuit |
| Lifecycle | Active |
| Datasheet reference | Molex Mini-Fit Jr 5557/0039012040 datasheet, rev. 2023-02, the current derating table by wire gauge and the crimp specification |
|---|---|
| Manufacturer | Molex |
| Mounting | Wire-to-board (mates with 5566/5569 headers) |
Substitute graph
3 Alternates
Interchangeable part numbers for this profile. A solid node is already profiled in this catalogue; a hollow node is a valid substitute that has no profile yet.
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0039012041 not yet profiled
The panel-mount version of the same 4-circuit housing. Same contacts, same pitch, different mounting — the part numbers differ by one digit and the two are not interchangeable in a cable assembly.
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0039010040 not yet profiled
4-circuit housing in the same family but without the locking latch, relying on friction. Cheaper; it will vibrate loose in any application with a motor, which is why the latched version exists.
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0039012040 + 39000038 not yet profiled
The housing alone needs the crimp terminals (39-00-0038 for 18-24 AWG) ordered separately. This is the single most common ordering mistake with Molex connector systems: buying housings and no terminals.
Selection notes
The only prose on this page
9 A is wire-gauge dependent
The 9 A rating assumes 18 AWG wire in the crimp terminal. With 22 AWG the same connector is limited to about 5 A and with 24 AWG to about 3 A, because the crimp barrel and the wire become the thermal bottleneck, not the contact. If your design needs 9 A per circuit, the wire is part of the connector specification.
Crimp height is the whole reliability story
A Molex crimp has a specified crimp height tolerance of about ±0.05 mm. A crimp that is too loose has high resistance and heat; one that is too tight shears the strands and creates a mechanical weak point that fails under vibration. Use a ratcheting crimp tool with the correct die and measure the first ten crimps with a micrometer.
Mating cycles and the latch
The 30-cycle rating applies to the latch as much as the contacts. Repeated flexing of the locking latch without pressing the release tab breaks it, and a broken latch on a 9 A connector means the contact backs out under load, which on a 600 V rated circuit is a safety issue rather than an inconvenience.
Sources
NIST — https://www.nist.gov/standardsgov/compliance-faqs-rohs · Texas Instruments — https://www.ti.com/lit/an/slva840/slva840.pdf
| Sourcing — Availability risk | Mini-Fit Jr is one of the most widely copied connector systems in the industry, with compatible housings and terminals from dozens of suppliers. Genuine Molex terminals have better plating and a more consistent crimp barrel; on a 9 A circuit the difference is measurable as temperature rise. |
|---|---|
| Pinout and handling | Four circuits at 4.20 mm pitch with a positive locking latch and polarising ribs that prevent reverse insertion. The header half is a separate part number (5566 or 5569 depending on the mounting style), and the wire-to-board system only works when the header, housing and terminal are all from the matching series. |
Engineering information only. Verify every substitution against the manufacturer datasheet and your own operating conditions before committing a design. No pricing or vendor links appear on this page.