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 1 Circuit Voltage Below Threshold

DTC B1325 07: Device Power 1 Circuit Voltage Above Threshold

DTC B1325 4A: Device Power 1 Circuit Checksum Error

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 following control modules monitor the system voltage through the battery positive (B+) voltage circuits:

    •  Audio amplifier (AMP)
    • HVAC control module (HVAC)
    • Instrument panel cluster (IPC)
    • Passenger presence system (PPS)
    • Object alarm module (RPA)
    • Radio
    • TV antenna module (TVM)
    • Vehicle direction alert alarm warning (VDAAW)

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

Conditions for Running the DTC

    • The voltages supplied to the control modules are in the range of 7-26 V.
    • The ignition is ON.

Conditions for Setting the DTC

B1325 03

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

B1325 07

The control module detects a system voltage greater than 18 V for 5 seconds.

B1325 4A

The instrument panel cluster (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 serial data, which are disabled after a 3 minute delay.
    • The setting of other DTCs is inhibited.

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 or jump starting can cause this DTC to set.

Reference Information

Schematic Reference

    •  Radio/Navigation System Schematics
    •  HVAC Schematics
    •  Instrument Cluster Schematics
    •  Object Detection 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.
  2. The voltage should be between 12.6 and 15.5 V.
  3. If the battery voltage is not within the specified range, refer to Charging System Test
  4. Ignition OFF, disconnect the harness connectors of the appropriate control module.
  5. Ignition OFF and scan tool disconnected, open and close the driver door, and wait 1 minute.
  6. Test for less than 5.0 Ω between the ground circuits listed below and ground.
  7. • Terminal 8 X1 (AMP) (UQA)
    • Terminal 11 X1 (HVAC)
    • Terminal 5 (IPC)
    • Terminal 7 X1 (RPA)
    • Terminal 5 (PPS)
    • Terminal 8 X1 Radio
    • Terminal 4 (VDAAW)
    If greater than the specified range, test the ground circuit for an open/high resistance.
  8. Ignition ON, verify a test lamp illuminates between the IGN/B+ circuit listed below and ground.
  9. • Terminal 4 X1 (AMP) (UQA)
    • Terminals 9-18 X1 (HVAC)
    • Terminals 10-20 (IPC)
    • Terminal 1 X1 (RPA)
    • Terminal 1 (PPS)
    • Terminal 1 X1 Radio
    • Terminal 2 (VDAAW)
    If the test lamp does not illuminate , test the IGN/B+ circuit for a short to ground or an open/high resistance.
  10. If the circuits test normal, replace the appropriate control module.

Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

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