Environmental-Box Cooling Fan

Environmental-Box Cooling Fan Description

This function is required to control the Environmental-Box (E-Box) mounted cooling fan.
This fan provides cabin air into the E-Box to provide a cool temperature environment for the ECM fitted in the under-bonnet mounted E-Box.
The temperature is determined by an internally (to the ECM) mounted temperature sensor. The fan will be switched ON at 40° C ± 15° C and also tested for 2 seconds every engine start.

The ECM has power stage diagnostics for this signal with a fault being detected if any of the following conditions is satisfied:
1. E-Box cooling fan driver short circuit to battery positive, i.e. the driver voltage is greater than half the battery voltage when the driver is ON.
2. E-Box cooling fan driver short circuit to ground, i.e. the driver voltage is less than one third of the battery voltage when the driver is OFF.
3. E-box cooling fan driver open circuit, i.e. the driver voltage is greater than one third of the battery voltage but less than two thirds of the battery voltage when the driver is OFF.