Circuit Description
When the ignition switch is in the UNLOCK position, certain class 2
messages do not transmit. The instrument panel cluster (IPC) 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 8 volts between the ignition 1
voltage circuit and the battery positive voltage for 3 seconds. The IPC receives
a class 2 message indicating the battery voltage and compares this to the ignition 1
voltage.
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 IPC. |
Conditions for Clearing the DTC
| • | The DTC becomes history when the difference between the ignition 1
voltage and the battery voltage is only 3 volts for 3 seconds. |
| • | 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 IPC detects low voltage at the ignition 1 voltage circuit,
the IPC 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 IPC 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. |
