Scan Tool Diagnostics

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:
1. Select Instrument Panel Cluster.
2. Select Data Display.
3. Select Data List.

The following list will appear:
^ Data
^ Inputs
^ Outputs

The scan tool allows for the display class 2 values or the state of components commanded by the various systems, including the following systems:
^ ATC
^ BCM
^ HVAC
^ IPC
^ VCM

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 DTC(s) 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 DTC(s):
- Pending DTC(s)
- Current DTC(s)
- History DTC(s)
^ 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:
^ Diagnostic tables
^ Wiring diagrams
^ Descriptive text

The diagnostic table is a step-by-step procedure in order to determine the circuit or component that is the source of the problem. 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.