1. Connect a scan tool to the data link connector (DLC).
2. Turn the ignition switch to the RUN position.
3. Attempt to establish communication with the PCM.

Is communication established?

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Go to Diagnostic Starting Point - Data Link Communications in Data Link Communications

Go to Step 2

Inspect circuit 800 (TAN) for a poor connection or an open between the heater-A/C control and S 237.

Is there a fault in the circuit?

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Go to Step 3

Go to Step 5

Repair the fault in circuit 800 (TAN).

Is the repair complete?

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Go to Step 5

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Replace the heater-A/C control. Refer to Control Assembly Replacement in Instrument Panel, Gauges and Console.

Is the repair complete?

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Go to Step 5

Go to Step 5

Verify that the systems operates properly.

Does the system operate properly?

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System OK

Go to Diagnostic System Check