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 Descriptor
DTC P1A47: Battery Energy Control Module Hybrid Battery Voltage Sensor PerformanceCircuit/System Description
The battery energy control module (BECM) monitors the link voltage performance. If any voltage is off, this DTC will set.
The Link Voltage is the voltage on the 36 volt cable between the SGCM and the BECM, Pack voltage is the sum of all module voltages. refer to Hybrid Energy Storage Schematics for detailed information.
Conditions for Running the DTC
The engine is running.
Conditions for Setting the DTC
Absolute value (Link voltage - sum of all module voltages) is greater than 5 volts.
Action Taken When the DTC Sets
Does not affect Hybrid Operation.
Conditions for Clearing the DTC
The difference between the link voltage and the sum of pack voltages decrease below threshold.
Reference Information
Schematic Reference
Hybrid Energy Storage Schematics
Connector End View Reference
Hybrid Energy Storage Connector End Views
Electrical Information Reference
Scan Tool Reference
Special Tools
J 35616 GM Approved Terminal Test Kit
Circuit/System Testing
Caution: To help avoid personal injury, additional precautions must be taken prior to working on the generator control module or the generator starter. After removing the 36V battery cables from the generator battery, remove both engine wiring harness connectors from the generator control module. Wait at least 5 minutes and then remove the generator control module cover. Verify voltage levels at all 36V, 12V, and 3-phase connections, are less than 3 volts using a DMM before proceeding.
Caution: To help avoid personal injury, be careful when working in the vicinity of the generator battery disconnect control module. Internal components will still be live, 36V potential, even when the cover has been opened or removed.
Important: In order to avoid damaging BECM C1 and C2 connector terminals, the proper test probes should be used. The proper test probes are as follows:
| • | J-35616-65B for female terminals |
| • | J-35616-64B for male terminals |
- Remove the generator battery disconnect control module cover. Refer to Hybrid Battery Service Disconnect/Connect
- Measure and record the voltage at Main Contactor Relay C2.
- Depress and hold the service disconnect switch for 20 seconds and measure the voltage at Main Contactor Relay C1 to ground. The voltage should read the same as in step 2.
| ⇒ | If no voltage was measured at Main Contactor Relay C1 with service disconnect switch depressed, replace BECM. |
Repair Instructions
Perform the Diagnostic Repair Verification after completing the diagnostic procedure.
Control Module References for BECM replacement, setup, and programming
