The instrument cluster uses information from other systems
in order to deliver information to the driver. Review the general information
on the following items before further diagnosis:
• | How the instrument cluster computer system operates |
• | How each system interacts with the instrument cluster |
This step may prevent the following conditions from occurring:
• | Unnecessary parts replacement |
Use a scan tool in order to diagnose the instrument cluster when referred
to the instrument cluster in diagnostic procedures. In addition to displaying
Diagnostic Trouble Codes (DTCs), the scan tool display may display the following
information:
The scan tool may also cycle many of the following components both on
and off.
Any of these features may be selected using the scan tool.
Become very familiar with the following instrument cluster information:
• | The diagnostic features |
The self-diagnostic features are referenced in the DTC tables. These
features are very useful in diagnosing non-DTC setting malfunctions as well.
Not all circuits that feed information to the instrument cluster will set
a code if the fault exists within that circuit. The following circuits will
not set a trouble code:
• | The windshield washer solvent level switch input |
• | The engine coolant level indicator module switch inputs |
The diagnostic tables concerning these circuits are still included within
this cell in order to help locate the concerns. Perform the Instrument Cluster
Diagnostic System Check, these tables will assist in diagnosis.
Replace the instrument cluster only if the diagnostic procedures specifically
direct you to do so. The instrument cluster does not automatically need to
be replaced when a short is found in the wiring. Repair the wiring first.
Inspect the system for further concerns. Most system malfunctions are traceable
to one of the following conditions:
The instrument cluster is very reliable. The instrument cluster is usually
not the cause of a system malfunction. Replacing the instrument cluster before
a complete diagnosis will usually result in a recurrence of the original complaint.
Display Input Status
The scan tool also displays the instrument cluster status. Select the
instrument cluster status display in order to display the data. Determine
if the switched inputs may be properly interpreted. The display also indicates
if the input has changed states. For example, when the engine coolant level
is OK, the scan tool displays the input status of the engine coolant level
switch as INACTIVE. When the engine coolant level is low, the scan tool reads
ACTIVE. Use this kind of information when diagnosing a malfunction associated
with one of the following conditions:
• | A particular instrument cluster input |
• | An input that is shared using another system |
Cycle Indicators and Gauges
Use a scan tool in order to cycle the following instrument cluster components:
This feature may be used in order to determine if the instrument cluster
is able to cycle the indicator or gauge regardless of the condition following
components:
• | Any specific program instructions |
Once a test is selected, the scan tool will command the instrument cluster
in order to energize the selected indicator or gauge. The displayed information
represents only what the instrument cluster commands. The displayed information
does not display what action has actually taken place. Inspect the instrument
cluster for the ability in order to control each of the selected indicator
and gauge functions.
Intermittents and Poor Connections
Intermittent failures in electronic systems may be very difficult to
detect and accurately diagnose. The instrument panel cluster tests for different
malfunctions under different vehicle conditions. For this reason, a thorough
test drive is often needed in order to repeat a fault condition. If the system
malfunction is not repeated during the drive test, a good description of the
complaint may be useful in locating an intermittent fault condition. The following
faulty components cause most intermittent problems:
When you suspect an intermittent condition, inspect the suspected circuits
for the following conditions:
• | Poor mating of the connector halves |
• | Improperly formed or damaged terminals |
• | Poor wire-to-terminal connections |
• | Dirty or corroded terminals |
• | Damage to the connector bodies |
The history DTCs indicate that the instrument cluster has previously
detected a malfunction. The reason may be one of the following conditions:
• | The malfunction is intermittent. |
• | The system for which the DTC is set for is not currently being
operated. |
Use a scan tool in order to try clearing the DTCs and manually operating
the system that the DTC applies to, if the following conditions occur:
• | The instrument cluster displays history DTCs. |
• | The malfunction cannot be found easily. |
Read the Diagnostic Aids and Conditions for Setting the DTC in each
DTC table for more specific information.
History DTCs help in diagnosing the intermittent fault conditions but
do not necessarily indicate a faulty instrument cluster. Most system complaints
are linked to the following conditions:
Perform a thorough inspection of all the related wiring and connectors
pertaining to the history DTC that is stored.
The following conditions may result in an intermittent instrument cluster
operation using no DTC stored:
• | Any condition which results in the interruption of power to the
instrument cluster |
• | The battery or ignition voltage out of range (below 9.0 V
or above 16.0 V) |
• | A loose or damaged ground |
• | An open or short on the serial data line |
DTCs Current and History
The instrument cluster stores the DTCs as one of the following codes:
If the instrument cluster detects a system malfunction, the instrument
cluster will only store a DTC that corresponds to that particular malfunction.
Some DTCs may remain current until the first ignition cycle if the following
conditions occur:
• | A current DTC is stored. |
• | The fault is no longer present. |
Other DTCs will go history under the following conditions:
• | The fault is no longer present. |
• | The fault does not require an ignition cycle. |
The history DTCs are intermittent malfunctions. These must be diagnosed
differently than the current DTCs. Refer to Intermittents and Poor Connections
above.