GM Service Manual Online
For 1990-2009 cars only

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 class 2 message from the serial data gateway module (SDGM) indicating the current power mode.

DTC Descriptor

This diagnostic procedure supports the following DTC:

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

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.
    • The IPC receives a clear code command from the scan tool.

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.