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Home >> Cadillac >> 2016 >> ELR >> Repair and Diagnosis (Single Page) >> Accessories & Equipment >> Communication Devices >> Data Communication System - DTC B1000 To DTC U183B >> Diagnostic Information and Procedures >> DTC U1839: Auxiliary Transmission Fluid Pump Control Module Lost Communication with Engine Control Module >> Circuit/System Description
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Circuit/System Description

Devices connected to the serial data circuits monitor for serial data communications during normal vehicle operation. Operating information and commands are exchanged among the devices. The devices have prerecorded information about what messages are needed to be exchanged on the serial data circuits, for each virtual network. The messages are supervised and also, some periodic messages are used by the receiver device as an availability indication of the transmitter device. Each message contains the identification number of the transmitter device.

The communication for Auxiliary Transmission Fluid Pump Control Module and all Drive Motor Control Modules 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 all Drive Motor Control Modules and the Hybrid/EV Powertrain Control Module 1, are all diagnosed from external sources only to the Power Inverter Module connector.