2-Pin 9.5mm High-Current Fuse Protector Connector – OEM 7123-4129-90 / 7122-4129-900 | Sumitomo
OEM-specification 2-pin high-current connector for automotive fuse protector and power distribution harness applications. Cross-references Sumitomo part numbers 7123-4129-90 (male/plug side) and 7122-4129-900 (female/socket side). The 9.5mm terminal pitch is the automotive standard for high-current fuse and main relay circuits, providing the contact area required for battery feed, main fuse, and fusible link connections. Available bare or with pre-wired leads.
The 9.5mm pitch is used exclusively for the highest-current circuits in the vehicle — battery feeds, main fuses, fusible links, and alternator output connections. The large terminal contact area minimises contact resistance, which is critical because even a small increase in resistance at a high-current connection causes significant voltage drop and heat generation. A corroded 9.5mm fuse connector can cause:
| Part Number | Type | Manufacturer |
|---|---|---|
| 7123-4129-90 | Male (plug side) — fuse / component side | Sumitomo |
| 7122-4129-900 | Female (socket side) — harness side | Sumitomo |
| Pin | Function | Current Rating | Failure Symptom if Corroded |
|---|---|---|---|
| 1 | High-current power input (battery feed / fuse input) | Up to 80A+ | Voltage drop, heat generation, multiple circuit failures |
| 2 | High-current power output (fuse output / load feed) | Up to 80A+ | Protected circuit not receiving power, false fuse blow |
| Attribute | Detail |
|---|---|
| Pin Count | 2-Pin |
| Part Numbers | 7123-4129-90 / 7122-4129-900 (Sumitomo) |
| Terminal Pitch | 9.5mm (high-current automotive standard) |
| Current Rating | High-current (fuse protector / main relay application) |
| Housing Material | High-temp nylon (PA66), heat-resistant |
| Terminal Material | Copper alloy, tin-plated |
| Wire Option | Bare connector / pre-wired leads |
| Application | Fuse protector harness, main relay harness, power distribution harness |
| Pitch | Typical Application | Current Range |
|---|---|---|
| 1.0–1.5mm | ECU signal circuits, CAN bus | <5A |
| 2.8mm | Sensor signals, low-current control | 5–15A |
| 6.3mm | Ignition switch, relay coils, medium-current | 15–30A |
| 9.5mm | Fuse protectors, main relays, battery feeds | 30–100A+ |
Q: Multiple unrelated circuits are failing simultaneously — could it be the fuse connector?
A: Yes. A corroded 9.5mm fuse protector connector causes voltage drop on the main power feed, which affects all circuits downstream of that fuse. Multiple simultaneous circuit failures from different systems (engine, body, lighting) with no single fault code pointing to one system is a classic sign of a corroded main fuse or power distribution connector.
Q: My fuse keeps blowing but there is no short circuit — what is causing it?
A: A corroded high-current connector generates heat due to increased contact resistance. This heat can cause the fuse to blow at normal operating current — a condition called “thermal blow” rather than overcurrent blow. If the fuse blows repeatedly with no identifiable short circuit, inspect the 9.5mm connector before replacing the fuse or wiring.
Q: Are terminals included?
A: Yes, terminals are included with all variants.
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