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

DTC B1325 4A: Device Power Circuit Checksum Error - IPC

Diagnostic Fault Information

Circuit

Short to Ground

Open/High Resistance

Short to Voltage

Signal Performance

B+

B1325 03, B1325 4A

B1325 03, B1325 4A

--

--

Ground

--

B1325 03, B1325 4A

--

--

Circuit/System Description

The control modules on this vehicle monitor the voltage on the battery positive (B+) voltage circuits. The following modules on this vehicle will set DTC B1325 if high or low battery voltage is detected:

    • Instrument panel cluster (IPC)
    • Passenger presence system (PPS)
    • Radio

Conditions for Running the DTC

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

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.

B1325 4A

The IPC failed the power on checksum test, either due to low voltage or corrupted memory.

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, which is disabled after a 3 minute delay.
    • The setting of other DTCs is inhibited.

Conditions for Clearing the DTC

The DTC clears 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 or jump starting can cause this DTC to set.

Reference Information

Schematic Reference

    •  Instrument Cluster Schematics
    •  SIR Schematics
    •  Radio/Navigation System Schematics

Connector End View Reference

    •  Displays and Gages Connector End Views
    •  SIR Connector End Views
    •  Entertainment/Communication 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

    •  Scan Tool Output Controls
    •  Scan Tool Data List
    •  Scan Tool Data Definitions

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 .
  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 appropriate ground circuit terminals listed below and ground:
  5. • Terminal 6 (IPC)
    • Terminal D (PPS)
    • Terminal 8 X1 (Radio)
    If greater than the specified range, test the ground circuit for an open/high resistance.
  6. Verify that a test lamp illuminates between the appropriate B+ circuit terminals listed below and ground:
  7. • Terminal 14 (IPC)
    • Terminal A (PPS)
    • Terminal 1 X1 (Radio)
    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.