GM Service Manual Online
For 1990-2009 cars only

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 B1325 03: Device Power Circuit Voltage Below Threshold

DTC B1325 07: Device Power Circuit Voltage Above Threshold

Diagnostic Fault Information

Circuit

Short to Ground

Open/High Resistance

Short to Voltage

Signal Performance

B+

B1325 03

B1325 03

--

--

Ground

--

B1325 03

--

--

Circuit/System Description

The following control modules monitor the battery voltage on the battery positive (B+) voltage circuit:

    • Body control module (BCM)
    • Instrument panel cluster (IPC)
    • Passenger presence system (PPS)
    • Radio
    • Sensing and diagnostic module (SDM)
    • Theft deterrent module (TDM)

If any of the modules listed detects that the battery voltage is out of range, it will set DTC B1325.

Conditions for Running the DTC

    • The ignition is ON.
    • The battery voltage supplied to the control modules is in the range of 7-26 volts.

Conditions for Setting the DTC

B1325 03

The control module detects that the system voltage is less than 9 volts for 5 seconds.

B1325 07

The control module detects that the system voltage is greater than 18 volts for 5 seconds.

Action Taken When the DTC Sets

The control module immediately disables all outputs when an out of range voltage condition has been detected, with the exception of GMLAN and the run/crank relay, which is disabled after a 3 minute delay.

Conditions for Clearing the DTC

The DTC passes when the malfunction is no longer present.

Diagnostic Aids

    • A high or low voltage value in multiple modules indicates a concern in the charging system.
    • Overcharging with a battery charger can cause this DTC to set.

Reference Information

Schematic Reference

    •  Body Control System Schematics
    •  Immobilizer Schematics
    •  Instrument Cluster Schematics
    •  Radio/Navigation System Schematics
    •  SIR Schematics

Connector End View Reference

Component Connector End Views

Description and Operation

Charging System 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

Circuit/System Testing

  1. Engine running, accessories OFF, measure and record the battery voltage at the battery terminals. The voltage should be between 12.6 and 15.0 volts.
  2. If not within the specified range, refer to Charging System Test .

    Caution: Refer to SIR Caution in the Preface section.

  3. Ignition OFF, disconnect the harness connectors at the appropriate module.
  4. Ignition OFF and scan tool disconnected, open and close the driver door, and wait 1 minute. Test for less than 5 ohms between the following ground circuit terminals and ground:
  5. • Terminal 4 (TDM)
    • Terminal 6 (IPC)
    • Terminal 31 (SDM)
    • Terminal 6 X1 (PPS)
    • Terminal 8 X1 (Radio)
    • Terminal 12 X1 (BCM)
    • Terminal 13 X2 (BCM)
    • Terminal E12 X4 (BCM)
    If greater than the specified range, test the ground circuit for an open/high resistance.
  6. Verify that a test lamp illuminates between the following B+ circuit terminals and ground:
  7. • Terminal 1 (SDM)
    • Terminal 2 (TDM)
    • Terminal 14 (IPC)
    • Terminal 1 X1 (PPS, Radio)
    • Terminal D12 X3 (BCM)
    If the test lamp does not illuminate, test the B+ circuit for a short to ground or an open/high resistance.
  8. If all circuits test normal, replace the appropriate module.

Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

Control Module References for the appropriate module replacement, setup, and programming.