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 Descriptor

DTC B1365: Device Ignition 0 (UNLOCK, ON and START) Circuit

Circuit Description

The instrument panel cluster (IPC) uses the ignition 0 voltage circuit in order to supply voltage to various indicators and gages. The IPC also receives a serial data message from the serial data gateway module (SDGM) indicating the current power mode.

Conditions for Running the DTC

The ignition is ON.

Conditions for Setting the DTC

The ignition 0 voltage circuit is less than 75 percent of battery voltage for more than 1 second.

Action Taken When the DTC Sets

    • The fuel gage, tachometer and speedometer default to 0.
    • The scan tool does not communicate with the instrument cluster.

Conditions for Clearing the DTC

    • The current DTC clears when the conditions for setting the DTC are no longer present.
    • The history DTC clears after 100 malfunction free ignition cycles.

Diagnostic Aids

    • When the instrument cluster detects low voltage at the ignition 0 voltage circuit, the instrument cluster will not communicate with the scan tool, and the fuel gage, tachometer and speedometer default to 0.
    • DTC B1365 can only be read by the scan tool as a history code in the IPC once the fault is removed.
    • This DTC cannot be retrieved with a current status. Refer to Scan Tool Does Not Communicate with Class 2 Device , for diagnosis of a loss of communication with the instrument cluster.
    • An intermittent condition is likely to be caused by an open condition in the ignition 0 voltage circuit. Refer to Scan Tool Does Not Communicate with Class 2 Device , in order to isolate an intermittent condition.

Reference Information

Schematic Reference

Instrument Cluster Schematics

Connector End View Reference

Component Connector End Views

Description and Operation

Instrument Cluster 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

Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

Control Module References for IPC replacement, setup, and programming