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: Voltage Below Threshold

DTC B1325 07: 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 control modules monitor the battery voltage on the B+ circuits. The battery voltage must be within the normal range in order for the control modules to operate correctly. If the battery voltage is out of range, the control modules listed below will set DTC B1325.

    • The IPC
    • The PPS
    • The Radio

Conditions for Running the DTC

The ignition is ON.

Conditions for Setting the DTC

B1325 03

The control module detects a system voltage less than 9 V for 5 seconds.

B1325 07

The control module detects a system voltage greater than 18 V 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 serial data, which is disabled after a 3 minute delay.
    • The setting of other DTCs is inhibited.

Conditions for Clearing the DTC

    • The DTC will pass when the condition for setting the DTC is no longer present.
    • A history DTC will clear when the DTC does not fail in 100 consecutive ignition cycles.

Diagnostic Aids

    • A high or low voltage value in multiple modules indicates a concern in the charging system.
    • Possible causes of this DTC are overcharging with a battery charger or jump starting.

Reference Information

Schematic Reference

    •  Instrument Cluster Schematics
    •  SIR Schematics
    •  Radio/Navigation System 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 V.
  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 30 seconds. Test for less than 5 Ω between the appropriate ground circuits listed below and ground.
  5. • Terminal 13 (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 2 (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.