The numbers below refer to the step numbers on the diagnostic table.
Lack of communication may be due to a partial malfunction of the class 2 serial data circuit or due to a total malfunction of the class 2 serial data circuit. The specified procedure will determine the particular condition.
This step determines if the engine control module (ECM) has set any DTCs related to the HVAC system.
Step  | Action  | Yes  | No  | ||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
1  | Did you review the HVAC Preliminary Checks in Heating, Ventilation, and Air Conditioning?  | Go to Step 2  | Go to HVAC Preliminary Checks in Heating, Ventilation and Air Conditioning  | ||||||||||
2  | Install a scan tool. Does the scan tool power up?  | Go to Step 3  | Go to Scan Tool Does Not Power Up in Data Link Communications  | ||||||||||
 Does the scan tool communicate with the ECM?  | Go to Step 4  | Go to Scan Tool Does Not Communicate with Component in Data Link Communications  | |||||||||||
Select the display DTCs function on the scan tool for the ECM. Does the scan tool display DTC P0532, P0533, or P0645?  | Go to Step 5  | ||||||||||||
5  | Does the scan tool display any other DTCs?  | Go to 
 
 
 
 
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