Diagnostic Instructions

DTC Descriptors

DTC B137A 01: Hybrid Accessory Wake Up Circuit - Short to Battery

DTC B137A 06: Hybrid Accessory Wake Up Circuit - Short to Ground or Open

Diagnostic Fault Information

Circuit	Short to Ground	Open/High Resistance	Short to Voltage	Signal Performance
Wake Up Signal	B137A 06*	1	2	--
* Will also set U1812 in the HPCM Open at SDGM or BECM will cause DTC U1812 in HPCM. Open at PIM will cause DTC U189A in the HPCM. Parasitic drain on battery, and will set DTC U1875, U1876, U1878, U1879 as history in the HPCM with the key ON, or as current with the key OFF.

Circuit/System Description

Modules connected to the high and low speed GMLAN serial data circuits monitor for serial data communications during normal vehicle operation. Operating information and commands are exchanged among the modules. The modules 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 module as an availability indication of the transmitter module. Each message contains the identification number of the transmitter module.

The wake up signal circuit is energized by the serial data gateway module (SDGM) to activate the drive motor generator power inverter module (PIM) and the drive motor generator battery control module (BECM) immediately when the body control module (BCM) signals the SDGM that serial data is required.

Conditions for Running the DTC

Conditions for Setting the DTC

A short to ground exists on the wake up signal circuit of the SDGM.

Action Taken When the DTC Sets

The malfunction indicator lamp (MIL) will illuminate and several driver information center (DIC) messages will scroll.

Conditions for Clearing the DTC

Reference Information

Schematic Reference

Connector End View Reference

Component Connector End Views

Description and Operation

Data Link Communications Description and Operation

Electrical Information Reference

Scan Tool Reference

Control Module References for scan tool information

Special Tools

Circuit/System Testing

Danger: Always perform the High Voltage Disabling procedure prior to servicing any High Voltage component or connection. Personal Protection Equipment (PPE) and proper procedures must be followed.

The High Voltage Disabling procedure will perform the following tasks:

•	Identify how to disable high voltage.

•	Identify how to test for the presence of high voltage.

•	Identify condition under which high voltage is always present and personal protection equipment (PPE) and proper procedures must be followed.

Failure to follow the procedures exactly as written may result in serious injury or death.

1. Perform the Hybrid Battery Service Disconnect/Connect procedure.
2. Reconnect the 12-volt battery.
3. Ignition OFF, disconnect harness connector X1 of the BECM and the PIM.
4. Ignition ON, verify that a test lamp illuminates between the wake up signal circuit of the PIM and ground, and the BECM and ground as follows:

•

PIM X1 19

•	BECM X1 12

⇒	If the test lamp does not illuminate, test the circuit for a short to ground or open/high resistance. If the circuit tests normal, replace the SDGM.

5. Ignition OFF, verify that a test lamp does not illuminate between the PIM wake up signal circuit terminal 19 and ground.

⇒	If the test lamp illuminates, test the circuit for a short to voltage. If the circuit tests normal, replace the SDGM.

6. If all circuits test normal, replace the SDGM.

Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

Control Module References for module replacement, setup, and programming