The scan tool may be used in order to monitor the communications
between the IPC and other Class 2 devices. The scan tool may also display
IPC data. The IPC DATA LIST display is under the Instrument Panel Cluster
selection. This list shows the status of the inputs and outputs to the IPC.
These scan tool values may be very useful in diagnosing the IPC.
Scan Tool Information Modes
The scan tool has four modes available in the Instrument Panel Cluster
selection.
Perform the following steps:
- Select Instrument Panel Cluster.
- Select Data Display.
- Select Data List.
The following list will appear:
The scan tool allows for the display class 2 values or the state
of components commanded by the various systems, including the following systems:
The tests available are dependent upon the system selected, but may
include the following tests:
Data (Analog Inputs): This test displays analog values as seen by the system.
Inputs (Digital Inputs): This test displays digital values as seen by the system and provides
an indication of whether the input has cycled.
Outputs (Digital Outputs): This test cycles digital outputs controlled by the system OFF/ON
for 3 seconds each cycle.
Overrides (Analog Outputs): This test allows for analog outputs of the system to be set at
a desired value.
Clear Diagnostic Trouble Codes (DTCs): This test will erase all of the DTCs stored for the system currently
selected. If the malfunction is still present, the DTC may immediately reset.
The Diagnostic Executive
The Diagnostic Executive is a unique segment of software that is designed
in order to perform the following functions:
| • | Coordinate the diagnostic procedures |
| • | Prioritize the diagnostic procedures |
| • | Define the protocol for recording and displaying the results |
| • | Receives diagnostic test results |
| • | Records the pass and fail status of test results |
The Diagnostic Executive has the following responsibilities:
| • | Monitoring the diagnostic test enabling conditions |
| • | Recording the following DTCs: |
| • | Monitoring and recording test status information |
| • | Recording pass and fail status of test results |
A diagnostic test is a series of steps that has a beginning and an end.
The result is a pass or fail reported to the Diagnostic Executive.
When a diagnostic test reports a pass result, the Diagnostic Executive
records the following data:
The fault identified by the diagnostic test is not currently active.
When a diagnostic test reports a fail result, the Diagnostic Executive
records the following data:
| • | The fault identified by the diagnostic test is currently active. |
| • | The fault identified has been active since the last 100 ignition
cycles or since the codes have been cleared. |
| • | Code supported BIT is enabled. |
Diagnostic Trouble Code (DTC) Diagnosis
This section provides the following aids in order to locate and repair
the problem:
The diagnostic table is a step-by-step procedure in order to determine
the circuit or component that is the source of the problem. The wiring diagrams
and text describing the system, test conditions, failure conditions and actions
taken when a DTC is set are located on the page facing the diagnostic table.
Diagnostic Trouble Codes (DTC)s, when set, indicate that the IPC has detected
a malfunction in a particular circuit or other system. Other system malfunctions
are generally (but not exclusively) reported to the IPC via Class 2
data message. The IPC is programmed with routines for internal checks that
are followed only under prescribed conditions (Test Conditions). When these
conditions exist, the IPC inspects certain circuits or systems for a malfunction.
These inspections are called Failure Conditions or Conditions for Setting
the DTC. When these conditions are true, a DTC is set. The IPC may turn
a Telltale Malfunction Indicator Lamp (MIL) ON. Refer to the Applicable DTC
Table for procedures and details.
