I. Core Specifications

Model: 21918597 (VOE21918597, Volvo Genuine Part Number)

Aliases: 21631327, 24170981 (Replacement / Related Numbers)

Voltage: 24VDC (Coil / Operating Voltage)

Type: Solid-State Control Module (Not a purely mechanical relay)

Terminals: 4-Pin Waterproof Connector

Functions: ECU Power Control, Starter Circuit Safety Lockout, Over-voltage / Under-voltage Protection, Engine Shutdown Control

Operating Temperature: -40°C to +85°C; Vibration-resistant, Dustproof, and Waterproof

Power Consumption: Approx. 3W

II. Applicable Engines / Units

Volvo Penta: TAD1641GE, TAD1642GE, TAD1241GE, TAD734GE (Primary models for generator sets)

Applicable Equipment Models:

Industrial Generator Sets: 1140-42VE, 1500-50VE, etc.

Marine Engines: D16, D12, D7 Series

Construction Machinery: Volvo EC Series Excavators (High-spec / Generator Set versions)

III. Functional Description (Distinction from Standard Relays)

ECU Power Management: When the ignition key is turned to the "ON" position, power supply to the ECU is delayed to prevent voltage surges. 

Starter Safety Lockout: Disconnects the starter circuit if no neutral signal is detected or if the safety interlock is not engaged. 

Voltage Protection: Automatically disconnects the load in 24V systems in the event of **over-voltage (>30V) or under-voltage (<18V)**. 

Engine Shutdown Control: Cuts power to the fuel solenoid valve during shutoff to ensure a rapid and clean engine stop.