Circuit/System Description
The hybrid/EV battery pack cooling fan draws air through the hybrid/EV battery pack to control the temperature of the hybrid/EV battery pack. To operate, the cooling fan receives an enable signal from the starter/generator control module. The enable control is controlled by a discrete high side driver in the starter/generator control module. When the enable control circuit is high, the fan will be enabled. The fan speed is controlled by a fan control circuit from the starter/generator control module, by changing the duty cycle. Maximum fan speed is 3900 RPM. Hybrid/EV battery pack cooling fan enable circuit open and short to voltage diagnostics run continuously until hybrid/EV battery pack cooling fan is enabled to run while short to ground runs after it is enabled to run. These diagnostics detect and report a failure of the fan enable circuits.