Functional Description - Powertrain Control Module (Pcm)

The PCM is a digital computer containing a micro-controller. The PCM receives input signals from various switches and sensors that are referred to as PCM Inputs. Based on these inputs, the PCM adjusts various engine and vehicle operations through devices that are referred to as PCM outputs.

The PCM is powered by a fuse located in the PDC. The PCM uses the Controller Area Network-Chassis (CAN-C) bus to perform engine diagnostics and flash operations.

The PCM manages the cooling fan activation and speed selection by sending a desired duty cycle (%) at a specified frequency (Hz) to the radiator fan. The PCM controls activation and deactivation of cooling fan to protect engine from been over heated. The activation, speed selection and deactivation of the radiator fan is based on the value of engine thermal variables that PCM continuously monitors through direct equipped sensors, an estimated algorithms, or it could be through request via CAN-C or Controller Area Network-Electronic Power Train (CAN-EPT).

The PCM receives the following:

CAN-C Inputs 

• Electronic Climate Control (ECC)/Heating, Ventilation, & Air Conditioning (HVAC) request
• A/C refrigerant pressure sensor information.
• Engine oil temperature
• Engine coolant temperature
• Engine RPM
• Engine run status
• Intake air temp
• Engine thermal management demand
• Vehicle speed
• Commanded ignition switch status
• Hood ajar status
• Ambient temp sensor voltage
• Maximum A/C demand to powertrain
• Transmission fluid temperature

CAN-EPT Inputs 

• Air flow request

The PCM provides the following:

CAN-C Outputs 

• Fan PWM duty cycle command [%]

CAN-EPT Outputs 

• Radiator fan request

Hard-wired Outputs 

• PWM command signal to the electric cooling fan