DC Power Conversion Test

DC Power Conversion Test

Diagnostic Instructions

* Perform the Diagnostic System Check - Vehicle Diagnostic System Check - Vehicle prior to using this diagnostic procedure.
* Review Strategy Based Diagnosis Strategy Based Diagnosis for an overview of the diagnostic approach.
* Diagnostic Procedure Instructions Diagnostic Procedure Instructionsprovides an overview of each diagnostic category.

Circuit/System Description

The accessory DC power control module supplies the energy that flows between the high voltage (300 volt) direct current (DC) and low voltage (14 volt) DC to charge the 12 volt battery and power accessories. The accessory DC power control module receives a wake-up signal on a discrete line from the serial data gateway module when the key is turned to RUN. After a successful engine start, the accessory DC power control module receives an enable command from the hybrid powertrain control module over the high speed hybrid GMLAN communication circuit to begin power conversion.

Diagnostic Aids

A poor connection at the B+ terminal of the accessory DC power control module or blown 200 Amp Mega-Fuse in the hybrid Bussed Electrical Center will prevent the accessory DC power control module from powering up and all values in the accessory DC power control module data list will read zero on the scan tool.

A poor connection on the accessory DC power control module wake-up signal X1 Terminal 3 from the serial data gateway module will also prevent the accessory DC power control module from powering up and all data values in the accessory DC power control module data list will read zero on the scan tool.

Reference Information
Schematic Reference

Hybrid Controls Schematics Hybrid Controls Schematics
Connector End View Reference

Component Connector End Views Connector End Views By Name
Description and Operation

Drive Motor Generator Control Module Description and Operation Drive Motor Generator Control Module
Electrical Information Reference

* Circuit Testing Circuit Testing
* Testing for Intermittent Conditions and Poor Connections Testing for Intermittent Conditions and Poor Connections

DTC Type Reference

Powertrain Diagnostic Trouble Code (DTC) Type Definitions Powertrain Diagnostic Trouble Code (DTC) Type Definitions

Circuit/System Verification

Engine ON, observe the charge indicator on the instrument panel cluster or message in the driver information center. The charge indicator on the instrument panel cluster should be turned OFF and the driver information center should not display charging system message.

If the charge indicator is not on the instrument panel cluster or a charging system message is not displayed on the driver information center, refer to Testing for Intermittent Conditions and Poor Connections Testing for Intermittent Conditions and Poor Connections.
If the charge indicator is on the instrument panel cluster or a charging system message is displayed on the driver information center, refer to Circuit/System Testing.

Circuit/System Testing

1. Ignition ON, verify that no generator or battery current sensor DTCs are set that would cause a charging system concern.

• If DTCs are set, refer to Diagnostic Trouble Code (DTC) List - Vehicle Diagnostic Trouble Code (DTC) List - Vehicle.

2. Ignition OFF, measure the voltage across the battery terminals. The voltage should read 12.0 volts or greater at room temperature.

• If not within specified value, refer to Battery Inspection/Test Battery Inspection/Test.

3. Connect a carbon pile tester to the battery.
4. Start the engine and turn all accessories off. Observe the voltage reading on the tester. The voltage should read between 12.6-15.5 volts.
5. Adjust the carbon pile tester so that the 12 volt current on the accessory DC power control module data list is reading 175 amps.

• If not within specified value, replace the accessory DC power control module.

Repair Instructions

Perform the Diagnostic Repair Verification Verification Tests after completing the diagnostic procedure.

Control Module References Programming and Relearningfor accessory DC power control module replacement, setup and programming.