Main Relay (Computer/Fuel System): Description and Operation

Main Relay:

PURPOSE
The Main Relay provides operating power to the Engine Control Module (ECM).

OPERATION
The Main Relay coil receives 12Volts DC from the battery through a fuse link. When the Ignition Switch is in the ON position, the coil of the Main Relay is grounded through pin 4 of the ECM. With the relay coil grounded, the contact switch closes and supplies 12Volts DC to pin 38 of the ECM.