GM Service Manual Online
For 1990-2009 cars only

The instrument cluster uses information from other systems in order to deliver information to the driver. Before further diagnosis, review the general information on how the instrument cluster computer system operates and how each system interacts with the instrument cluster. This will save diagnostic time, further misdiagnosis and unnecessary parts replacement.

Use a scan tool in order to diagnose the instrument cluster when referred to in diagnostic procedures. In addition to displaying Diagnostic Trouble Codes (DTCs), the scan tool displays the input status and the data values used. The scan tool can also cycle many of the indicators ON and OFF and perform sweep tests of the gauges. These features can be selected using the scan tool.

Become very familiar with the instrument cluster capabilities and diagnostic features. These self-diagnostic features are referenced in the DTC tables and are very useful in diagnosing non-DTC setting malfunctions as well. Notice that not all circuits feeding information to the instrument cluster will set a DTC if a fault exists within that circuit. Some of these circuits such as the windshield washer solvent level switch input and the engine coolant level indicator module switch inputs will not set a DTC. Diagnostic tables concerning these circuits are still included in this section to help locate concerns. Performing the instrument cluster diagnostic system check will help guide a technician to these tables to assist in diagnosis. Refer to Diagnostic System Check - Instrument Cluster for details.

Replace the instrument cluster only if the diagnostic procedures specifically directs 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, then check the instrument cluster for further concerns. Most instrument cluster malfunctions are traceable to faulty wiring and connectors and occasionally components. The instrument cluster is a very reliable and usually is not the cause of a system malfunction. Instrument cluster replacement before a complete diagnosis will usually result in a recurrence of the original complaint.