B1372

DTC B1372

Diagnostic Instructions

* Perform the Diagnostic System Check - Vehicle (Diagnostic System Check - Vehicle) prior to using the diagnostic procedure.
* Review Strategy Based Diagnosis (Strategy Based Diagnosis) for an overview of the diagnostic approach.
* Diagnostic Procedure Instructions (Diagnostic Procedure Instructions) provides an overview of each diagnostic category.

DTC Descriptor
DTC B1372
- Device Ignition 1 (ON and START) Circuit Low

Diagnostic Fault Information





Circuit Description

When the ignition switch is in the UNLOCK position, certain serial data messages do not transmit. The instrument cluster suspends the operation of the indicators and the gages that are dependent on these messages until the ignition switch is no longer in the UNLOCK position.

Conditions for Running the DTC

The ignition is ON.

Conditions for Setting the DTC

There is a difference of at least 75 percent between the ignition 1 voltage circuit and the instrument panel cluster (IPC) battery positive voltage circuit for 3 seconds.

Action Taken When the DTC Sets

* The odometer and the PRNDL displays do not illuminate.
* The fuel gage and the engine coolant temperature gage default to 0.
* The scan tool does not communicate with the instrument cluster.

Conditions for Clearing the DTC

* The DTC becomes history when the conditions for setting the DTC are no longer present.
* The history DTC clears after 100 malfunction-free warm-up cycles.

Diagnostic Aids

* When the instrument cluster detects low voltage at the ignition 1 voltage circuit, the instrument cluster will not communicate with the scan tool, and the odometer and PRNDL displays will not be illuminated. The season odometer will display if the trip reset switch is pressed, and the instrument cluster will communicate with the scan tool until the trip reset switch is released.
* An intermittent condition is likely to be caused by an open condition in the ignition 1 voltage circuit.
* DTC B1372 can only be read by the scan tool as a history code once the fault is removed. Refer to Scan Tool Does Not Communicate with Class 2 Device (Scan Tool Does Not Communicate with Class 2 Device) for diagnosis of a loss of communication with the instrument cluster.

Reference Information
Schematic Reference

Instrument Cluster Schematics (Instrument Cluster Schematics)
Connector End View Reference

Component Connector End Views (Connector Views)
Description and Operation

Instrument Cluster Description and Operation (Description and Operation)
Electrical Information Reference

* Circuit Testing (Circuit Testing)
* Connector Repairs (Connector Repairs)
* Testing for Intermittent Conditions and Poor Connections (Testing for Intermittent Conditions and Poor Connections)
* Wiring Repairs (Wiring Repairs)

Scan Tool Reference

Control Module References (Programming and Relearning) for scan tool information

Circuit/System Testing

1. Ignition OFF, disconnect the harness connector at the IPC.
2. Ignition ON, verify that a test lamp illuminates between the ignition 1 voltage circuit terminal B7 and ground.

• If the test lamp does not illuminate, test the ignition 1 voltage circuit for an open/high resistance. If the ignition 1 voltage circuit fuse is open, test the voltage circuit for a short to ground.

3. If all circuits test normal, test or replace the IPC.

Repair Instructions

Perform the Diagnostic Repair Verification (Verification Tests) after completing the diagnostic procedure.

Control Module References (Programming and Relearning) for IPC replacement, setup, and programming