Circuit/System Description

The serial data circuit is the means by which the devices in the vehicle communicate with each other. When the vehicle is ON, each device communicating on the serial data circuit sends a state of health message to ensure that the device is operating properly. When Hybrid/EV Powertrain Control Module 2 stops communicating on the serial data circuit, for example if the Hybrid/EV Powertrain Control Module 2 loses power or ground, the state of health message it normally sends on the serial data circuit disappears. Other devices on the serial data circuit, which expect to receive that state of health message, detect its absence; those devices in turn set a DTC associated with the loss of state of health of the Hybrid/EV Powertrain Control Module 2. A loss of serial data communications DTC does not represent a failure of the devices that contain the stored DTC.

The communication for Auxiliary Transmission Fluid Pump Control Module and Drive Motor Control Module is handled through the Hybrid/EV Powertrain Control Module 1. The Auxiliary Transmission Fluid Pump Control Module and the Hybrid/EV Powertrain Control Module 1 are all internal to the Power Inverter Module. All circuits to the Auxiliary Transmission Fluid Pump Control Module and Hybrid/EV Powertrain Control Module 1 are also internal to the Power Inverter Module. Communication diagnostics for the serial data, including device power and ground as well as the wakeup circuits, for Auxiliary Transmission Fluid Pump Control Module and the Hybrid/EV Powertrain Control Module 1 are all diagnosed from external sources only to the Power Inverter Module connector.