Accessory DC Power Control Module Description and Operation

Accessory DC Power Control Module Description and Operation

Location

The 14V Power Module, also called the Accessory DC Power Control Module, is located in the rear trunk compartment underneath the floor stowage trim panel. It is attached to the chassis with four fasteners and connected to a plastic cooling duct. The 14V Power Module has a high voltage pigtail that passes through the floor of the rear compartment and connects to a high voltage cable that comes from the hybrid battery pack. Also connected to the 14V Power Module are the 12V cables + positive and - negative, and a signal connector for serial data.

Operating Functions

The 14V Power Module is an electronic device that takes the place of the generator on a traditional vehicle. On a hybrid or electric vehicle the 14V power module converts high voltage (300V) direct current (DC) to low voltage (12V) DC for accessory electrical operation and to charge the 12 volt battery.

Normally, the 14V power module only supplies 12 volts DC when the vehicle is under a normal drive cycle. However there are certain instances when the vehicle is being charged through a standard wall socket where the14V power module operation is required to sustain the 12 volt battery.

The 14V power module is capable of supplying up to 180 Amps of 12 volt DC.

Communication and Hosted Diagnostics

The 14V power module has internal diagnostic tests that run at both power-up and during operation. All DTCs from the 14V power module are reported to and hosted by the hybrid powertrain control module. The 14V power module only communicates with the hybrid powertrain control module and only over serial data.

Circuit Inputs

Inputs to the 14V power module include the high voltage and 12 volt circuits. The 14V power module also has two 12 volt discrete inputs, Accessory and Run/Crank, either one has to be at a high level in order for it to wake up. The 14V power module is connected to the powertrain expansion communication circuit and communicates with the hybrid powertrain control module. The 14V power module monitors various internal components for current, voltage and temperature. The 14V power module will not begin supplying 12 volts DC until:

* Either the Accessory input or Run/Crank input are high, and
* The appropriate serial data enable signal is communicated by the hybrid powertrain control module.

The14V power module will not begin conversion of voltage however, until the appropriate serial data enable signal is sent by the hybrid powertrain control module.

For more information on the 12 V Battery Charging System, refer to Charging System Description and Operation Description and Operation.

Circuit Outputs

The only outputs supported by the 14V power module are serial data communications and 12 volts DC which powers the 12 volt components in the vehicle and charges the 12 volt battery. Low voltage 12V cables on the hybrid/EV vehicle do not require unique coloring or servicing procedures.