Circuit Description
When the ignition switch is in the UNLOCK position, certain class 2 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.
DTC Descriptor
This diagnostic procedure supports the following DTC:
DTC B1372 Device Ignition 1 (ON and START) Circuit Low
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. |
| • | The IPC receives the clear code command from the scan tool. |
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 in Computer/Integrating Systems for diagnosis of a loss of communication with the instrument cluster. |
Step | Action | Yes | No |
|---|---|---|---|
Schematic Reference: Instrument Cluster Schematics Connector End View Reference: Instrument Panel, Gages, and Console Connector End Views | |||
1 | Did you perform the Diagnostic System Check - Vehicle? | Go to Step 2 | Go to Diagnostic System Check - Vehicle in Vehicle DTC Information |
2 | Test the ignition 1 voltage circuit for an open or high resistance. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct the condition? | Go to Step 5 | Go to Step 3 |
3 | Inspect for poor connections at the harness connector of the instrument panel cluster (IPC). Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs in Wiring Systems. Did you find and correct the condition? | Go to Step 5 | Go to Step 4 |
4 | Replace the IPC. Refer to Control Module References in Computer/Integrating Systems for replacement, setup, and programming . Did you complete the replacement? | Go to Step 5 | -- |
5 | Operate the system in order to verify the repair. Did you correct the condition? | System OK | Go to Step 2 |
