Diagnostic Instructions
| • | Perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure. |
| • | Review Strategy Based Diagnosis for an overview of the diagnostic approach. |
| • | Diagnostic Procedure Instructions provides an overview of each diagnostic category. |
DTC Descriptors
DTC B137B 06: Accessory Power Module Wake Up Circuit - short to ground or openDiagnostic Fault Information
Circuit | Short to Ground | Open/High Resistance | Short to Voltage | Signal Performance |
|---|---|---|---|---|
Wake Up Signal | B137B 06 | U182A | U189A | -- |
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 accessory DC power control module (APM) immediately when the body control module (BCM) signals the SDGM that serial data is required.
Conditions for Running the DTC
| • | The system voltage is between 9-16 volts. |
| • | The vehicle power mode master requires serial data communication to occur. |
Conditions for Setting the DTC
The wake up signal circuit is shorted to ground.
Action Taken When the DTC Sets
The module is never signaled and the charging system will not operate. The battery indicator will illuminate along with multiple driver information messages.
Conditions for Clearing the DTC
| • | A current DTC clears when the malfunction is no longer present. |
| • | A history DTC clears when the module ignition cycle counter reaches the reset threshold of 50, without a repeat of the malfunction. |
Reference Information
Schematic Reference
Connector End View Reference
Description and Operation
Data Link Communications Description and Operation
Electrical Information Reference
Circuit/System Verification
With a scan tool, verify that DTC U182A is not set in the SDGM, and U189A is not set in the HPCM.
| ⇒ | If either DTC is present, refer to Diagnostic Trouble Code (DTC) List - Vehicle . |
Circuit/System Testing
- Ignition OFF, disconnect the harness connector X1 at the APM.
- Ignition ON, verify that a test lamp illuminates between the wake up signal circuit terminal 3 and ground.
- Ignition OFF and scan tool disconnected, verify that a test lamp does not illuminate between the signal circuit terminal 3 and ground.
- If all circuits test normal, replace the APM.
| ⇒ | If the test lamp does not illuminate, test the circuit for a short to ground or an open/high resistance. |
| ⇒ | If the test lamp illuminates, test the circuit for a short to voltage. |
Repair Instructions
Perform the Diagnostic Repair Verification after completing the diagnostic procedure.
| • | Control Module References for module replacement, setup, and programming |
