Engine Control Module (ECM)

The ECM directly controls the generator field control circuit input to the generator. It monitors the generator's generator field duty cycle signal circuit and sends the information to the BCM. The ECM will override the BCM control of the generator when one of the following conditions is met:

• The engine cooling fans are on high speed.
• There is a high fuel demand.
• The calculated ambient air temperature is less that 0°C (32°F).