Diagnostic Instructions
| • | Perform the Diagnostic System Check - Vehicle prior to using the 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 B1372: Device Ignition 1 (ON and START) Circuit LowDiagnostic Fault Information
Circuit | Short to Ground | Open/High Resistance | Short to Voltage | Signal Performance |
|---|---|---|---|---|
Ignition 1 Voltage | B1372 | B1372 | B1372 | -- |
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 for diagnosis of a loss of communication with the instrument cluster. |
Reference Information
Schematic Reference
Connector End View Reference
Description and Operation
Instrument Cluster Description and Operation
Electrical Information Reference
Scan Tool Reference
Control Module References for scan tool information
Circuit/System Testing
- Ignition OFF, disconnect the harness connector at the IPC.
- Ignition ON, verify that a test lamp illuminates between the ignition 1 voltage circuit terminal B7 and ground.
- If all circuits test normal, test or replace the IPC.
| ⇒ | 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. |
Repair Instructions
Perform the Diagnostic Repair Verification after completing the diagnostic procedure.
Control Module References for IPC replacement, setup, and programming
