1. Turn the ignition switch to OFF.
2. Install a scan tool.
3. Turn the ignition switch to RUN.
4. Attempt to communicate with the instrument cluster.

Does the scan tool communicate with instrument cluster?

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Go to Step 2

Go to Step 3

Test the instrument cluster for DTC's.

Are any DTC's stored?

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Go to Diagnostic Trouble Code (DTC) List/Type

System OK

Attempt to communicate with the other systems connected to the same serial data line.

Does the scan tool communicate with the other systems?

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Go to Step 4

Go to Scan Tool Does Not Communicate with Class 2 Data Line

1. Turn the ignition switch to OFF.
2. Disconnect the instrument cluster.
3. Measure the voltage between IP connector C1 terminal D15 (Oldsmobile) or terminals F14 and E14 (Buick) and ground.

Is the voltage within the specified range?

10-15 V

Go to Step 6

Go to Step 5

Repair the open or short to ground. Refer to Wiring Repairs .

Is the repair complete?

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Go to Step 9

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Measure the voltage between terminal D15 (Oldsmobile) or terminals F14 and E14 (Buick) and ground terminals D12 and C12 (Oldsmobile) and F12 and E12 (Buick).

Is the voltage within the specified range?

10-15 V

Go to Step 8

Go to Step 7

Repair the open. Refer to Wiring Repairs .

Is the repair complete?

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Go to Step 9

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Replace the instrument cluster. Refer to Instrument Cluster Replacement .

Is the replacement complete?

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Go to Step 9

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1. Turn the ignition switch OFF.
2. Reconnect all of the connectors and reinstall all of the components.
3. Clear any DTC's

Are all of the DTC's cleared?

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System OK

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