Glow Plug Relay
When the ignition (key) switch is placed in the ON position, a signal is sent to the ECM relating current engine coolant temperature. This signal is sent from the engine coolant temperature sensor.
The glow plug control module receives information about the glow function from the engine control module. The start of glow plug operation, the period of glow plug operation, the actuation frequency and the pulse duty factor are therefore determined by the engine control module.