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 link. The major function is to send or receive the different binary (bytes) information between the instrument cluster 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 and is able to determine the integrity of the operation.

Conditions for Setting the DTC

    • The instrument cluster is unsuccessful at verifying the oscillator's operation.
    • The oscillator is being disrupted by an outside radio frequency interference. Refer to Diagnostic Aids for more information.
    • Condition may occur at any time.

Action Taken When the DTC Sets

    • The instrument cluster stores DTC B0602 in memory.
    • The SERVICE VEHICLE SOON indicator turns on.

Conditions for Clearing the DTC

    • Under all fault conditions, the ignition switch must be cycled from on to off, then back to on, before this DTC will change from current to history.
    • A history DTC will clear after 100 drive cycles if the condition for this DTC is no longer present.
    • Using a scan tool

Diagnostic Aids

    • The oscillator is not removable form the instrument cluster and DTC B0602 is an internal malfunction to the instrument cluster. There is no repair procedure for this malfunction. Replace the instrument cluster.
    • The following conditions may cause an intermittent malfunction to occur:
       - Radio frequency (RF) interference induced into the Class 2 serial data link
       - Improperly installed aftermarket equipment
       - Illegal tampering with the instrument cluster

Test Description

The numbers below refer to the step numbers on the diagnostic table.

  1. Always perform the instrument cluster diagnostic system check before attempting to diagnose this DTC.

  2. This diagnostic procedure requires using a scan tool.

  3. This repair procedure requires instrument cluster replacement.

Step

Action

Value(s)

Yes

No

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 the instrument cluster DTC and retest for DTC B0602.

Does DTC B0602 reset?

--

Go to Step 3

Go to Powertrain On Board Diagnostic (OBD) System Check in Engine Controls - 3.5L

3

Replace the instrument cluster. Refer to Instrument Cluster Replacement .

Is the repair complete?

--

System OK

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