GM Service Manual Online
For 1990-2009 cars only

Circuit Description

The oscillator is a device used in the instrument cluster in order to send and interpret data between the other components along the class 2 serial data line. The major function of the oscillator is to send or receive the different binary (bytes) information between the instrument and the other components within the vehicle. When the ignition switch is first turned On, the instrument cluster performs an internal test on the oscillator. This test determines the integrity of the instrument cluster operation.

Conditions for Setting the DTC

    • The instrument cluster is unsuccessful at verifying the operation of the oscillator.
    • The oscillator is disrupted by an outside radio frequency interference.
    • The conditions may occur at any time.

Action Taken When the DTC Sets

    • The system stores a DTC B0602 in the instrument cluster memory.
    • The SERVICE VEHICLE SOON indicator illuminates.

Conditions for Clearing the DTC

    • The DTC becomes history when the ignition is cycled.
    • A history DTC clears after 100 drive cycles when the conditions for this DTC is no longer present.
    • The IPC receives the clear code command from the scan tool.

Diagnostic Aids

Use the Freeze Frame and/or Failure Records data in order to locate an intermittent condition. If you cannot duplicate the DTC, the information included in the Freeze Frame and/or Failure Records data may aid in determining the number of miles since the DTC set. The Fail Counter and Pass Counter can also aid in determining the number of ignition cycles that the diagnostic reported a pass and/or fail. Operate the vehicle within the same freeze frame conditions, i.e. RPM, load, vehicle speed, temperature, etc. This will isolate when the DTC failed.

Refer to Testing for Intermittent Conditions and Poor Connections in Wiring Systems.

Step

Action

Yes

No

Schematic Reference: Instrument Cluster Schematics

1

Did you perform the Instrument Cluster Diagnostic System Check?

Go to Step 2

Go to Diagnostic System Check - Instrument Cluster

2

Using a scan tool, clear DTC B0602.

Does DTC B0602 reset?

Go to Step 3

System OK

3

Replace the instrument cluster. Refer to Instrument Cluster Replacement .

Is the repair complete?

Go to Step 4

--

4

Use the scan tool in order to clear the DTCs.

Operate the vehicle within the conditions for running the DTC as specified in the supporting text.

Does the DTC reset?

Go to Step 2

System OK