Main Relay (System Relay)
The function of the main relay (system relay) is to supply certain components with voltage.
The relay is mechanical and has a closing and opening function. In the rest position the circuit in the relay is open.
The main relay terminals (#30 and #86) are supplied with voltage by the battery. When the start button on the start control module (SCU) has been activated and the engine control module (ECM) receives voltage, the terminal (#85) is grounded on the main relay of the engine control module (ECM).
When the terminal (#85) is grounded, the relay is activated and a number of components are powered via the relay terminal (#87).
The main relay is in the integrated relay/fusebox in the engine compartment and is diagnosed by the engine control module (ECM).