I. Basic Parameters

OE Part Number: 21N4-00762 (Abbreviated: 21N400762); DC24V; Factory-set fixed delay: 9.5 seconds; Electronic Start Delay Controller.

Connector: 4-pin white straight-plug connector; features a square plastic housing with integrated mounting tabs; designed for direct, non-destructive replacement—no wiring modification required.

Aliases: Start Timer Relay, Pre-heating Delay Module, Starter Delay Protection Relay.

II. Compatible Excavator Models (Hyundai -7 Series Mainstream Models)

Crawler Excavators

R80-7, R210LC-7, R215-7, R220-7, R225-7, R305-7, R330-7, R350-7, R220-9, R225-9 (Full range of Cummins-equipped models).

Wheeled Excavators / Wheel Loaders

HL730-7, HL740-7, HL757-7 (Full range of Hyundai -7 Series models).

III. Core Functions

Upon turning the ignition key to the "START" position, the unit initiates a 9.5-second delay before automatically cutting off power to the starter motor. This prevents damage caused by prolonged cranking—specifically, it safeguards against burning out the starter solenoid and stripping the starter gear teeth (acting as a safety mechanism against accidental, prolonged ignition attempts).

Integration with Pre-heating System: The unit releases the start signal only after the cold-engine pre-heating cycle is complete, thereby providing a dual-delay control mechanism that manages both pre-heating and engine starting sequences.

IV. Common Failure Symptoms

Turning the key causes the starter motor to crank continuously without stopping; resulting in a burnt-out starter motor: Indicates internal contact welding (sticking), signifying relay failure.

Upon turning the key, the starter motor spins for only one second before immediately losing power; the engine fails to start: Indicates damage to the internal timing circuit.

Cold-engine pre-heating functions normally, but there is no output signal for starting; the starter motor remains completely inactive: Indicates a failure within the starting control circuit.

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