Diagnostic procedure
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STEP
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INSPECTION
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RESULTS
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ACTION
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1
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Is customer complaint "Lack of passenger compartment heat" only?
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Yes
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Inspect the A/C and heater system.
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No
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Go to the next step.
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2
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Does the engine speed continue at fast idle?
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Yes
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Go to symptom troubleshooting "No.9 Fast idle/runs on".
(See NO.9 FAST IDLE/RUNS ON [L3].)
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No
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Go to the next step.
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3
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Remove the thermostat and inspect the operation.
(See THERMOSTAT INSPECTION.)
Is thermostat normal?
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Yes
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Go to the next step.
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No
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Replace the thermostat.
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4
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Inspect the cooling fan control system operation.
Does the cooling fan control system work properly?
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Yes
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Access ECT PID.
Inspect for both ECT PID and the temperature gauge on the instrument cluster readings.
If the temperature gauge on the instrument cluster indicates normal range but ECT PID is not the same as temperature gauge reading, inspect the ECT sensor.
If the temperature gauge on the instrument cluster indicates cold range but ECT PID is normal, inspect the temperature gauge and the heat gauge unit.
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No
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Repair or replace malfunctioning part.
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5
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Verify test results.
• If normal, return to diagnostic index to service any additional symptoms.
• If malfunction remains, replace PCM.
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