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 Circuit Range Performance
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. |
