De Dietrich 300009077 RAST 5 connector 3-pin Auxiliary pump

This RAST 5 connector is a 3‑pin component for use with an auxiliary pump in a boiler or burner system. Parts of this type serve as the electrical link between the control board and the pump, carrying the low‑voltage control signals or mains supply that start and stop the pump as needed. The RAST 5 series is defined by a specific pitch and keying profile, which ensures the connector can only be inserted into a matching header on the pump or the wiring harness. The 3‑pin configuration matches the typical connections for an auxiliary pump circuit, which may include a live, neutral, and earth conductor, or a switching line and feedback. When selecting a replacement connector of this type, the key parameters are the pin count, pitch, and keying – these must match the counterpart on the board or pump. The conductor cross‑section and insulation temperature class should also be considered, as the pump circuit may carry a modest continuous current and operate in a warm appliance environment. The terminal type (crimp, IDC, or solder) and the length of any pre‑stripped leads, if applicable, will affect ease of installation. Connectors in this class are a routine suspect during fault finding because poor contact can reproduce almost any electrical fault symptom – intermittent pump operation, failure to start, or erratic speed. Inspect the connector for corrosion, bent pins, or insulation damage before replacing the pump itself. Ensure the new connector is fully seated and the locking tab engages to prevent vibration‑induced loosening.