Engine Control Module (ECM)
WARNING: This page is about a different car, the 2008 Pontiac G5 and 2008 Chevrolet Cobalt. However, it is still accessible from the selected car via links, so may be relevant.
The ECM directly controls the generator field control circuit input to the generator. It monitors the generators 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 are 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).