GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 Saturn 🢒 2008 🢒 AURA 🢒 DTC 🢒 DTC P1A0E or P1A0F

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 P1A0E: Battery Energy Control Module Hybrid Battery Voltage Sensor Circuit Low Voltage

DTC P1A0F: Battery Energy Control Module Hybrid Battery Voltage Sensor Circuit High Voltage

Circuit/System Description

The battery energy control module (BECM) monitors the link voltage using 4 voltage sensors and a internal sensor to detect a low or high voltage condition.

Conditions for Running the DTC

The engine is ON.

Conditions for Setting the DTC

P1A0E

    • The internal voltage sensor is less than 0.5 volts.
    • The generator battery disconnect control module cover is not installed.

P1A0F

The internal voltage sensor is greater than 4.5 volts

Action Taken When the DTC Sets

Hybrid system is inactive.

Conditions for Clearing the DTC

Link voltage returns between the calibrated thresholds.

Reference Information

Schematic Reference

Hybrid Energy Storage Schematics

Connector End View Reference

Component Connector End Views

Description and Operation

Generator Battery Carrier Description and Operation

Electrical Information Reference

    •  Circuit Testing
    •  Connector Repairs
    •  Testing for Intermittent Conditions and Poor Connections
    •  Wiring Repairs

Scan Tool Reference

Control Module References for scan tool information

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 X1 and X2 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

P1A0E

  1. Remove the generator battery disconnect control module cover. Refer to Hybrid Battery Service Disconnect/Connect.
  2. Measure and record the voltage at Main Contactor Relay X2 to ground.
  3. Depress and hold the service disconnect switch and measure the voltage at Main Contactor Relay X1 to ground. The voltage should read the same as in step 2.
    4. ⇒If no voltage was measured at Main Contactor Relay X1 with service disconnect switch depressed, replace the BECM.
  4. Disconnect connectors X1 and X2 from the BECM.
  5. Test for less than 6.5 volts between X1 terminal 1 and X2 terminal 1, while depressing the service disconnect switch.
    6. ⇒If greater than the specified range, replace the BECM.
  6. Remove the generator battery cover. Refer to Generator Battery Temperature Sensor Replacement.
  7. Measure the resistance between X2 terminal 1 and Main Contactor Relay X1. Should measure between 1.3-1.7 k ohms.
    8. ⇒If not within specified range, replace the BECM.
  8. Measure the resistance between X1 terminal 1 and Generator Battery 1 X1. Should measure between 1.3-1.7 k ohms.
    9. ⇒If not within specified range, replace the harness assembly.

P1A0F

  1. Remove the generator battery disconnect control module cover. Refer to Hybrid Battery Service Disconnect/Connect.
  2. Measure and record the voltage at Main Contactor Relay X2 ground. Should read pack voltage.
  3. Measure the voltage at Main Contactor Relay X1 to ground. Should read no voltage.
    4. ⇒If greater than the specified range, replace the BECM.
  4. Disconnect connectors X1 and X2 from the BECM.
  5. Remove the generator battery cover. Refer to Generator Battery Temperature Sensor Replacement.
  6. Measure the resistance between X2 terminal 1 and Main Contactor Relay X1. Should measure between 1.3-1.7 k ohms.
    7. ⇒If not within specified range, replace the BECM.
  7. Measure the resistance between X1 terminal 1 and Generator Battery 1- X1. Should measure between 1.3-1.7 k ohms.
    8. ⇒If not within specified range, replace the harness assembly.

Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

    •  Generator Battery Temperature Sensor Replacement
    •  Control Module References for BECM replacement, setup, and programming