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- General Definition: A relay which responds to a signal with a certain delay. This means that the relay will activate or deactivate after a predefined time period once it receives a signal.
- Ignition Systems Application: In some ignition systems, a time delay relay allows for full vacuum advance 20-30 seconds after start-up. After this period, control is again taken up by the Transmission Control System (TCS). This delay helps the engine warm up properly before full vacuum advance is applied.
- Transmission Systems Application: Some cars have an additional time delay relay that delays vacuum advance about 30 seconds after the transmission has been shifted to high gear. This feature ensures smooth operation and efficient performance by preventing abrupt changes in engine vacuum advance, which could affect drivability and engine response.