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Home >> Chevrolet >> 2002 >> Blazer 4D Utility, 4WD, Part Time >> Repair and Diagnosis >> External Pages >> Different car >> Section 1545 (Engine Cooling System -- 5.7L) >> Diagnostic Information and Procedures >> Diagnostic System Check - Engine Cooling >> Test Description

Test Description

WARNING: This page is about a different car, the 2004 Chevrolet Corvette. However, it is still accessible from the selected car via links, so may be relevant.

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

  1. 2:  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.
  2. 3:  Determine if the Instrument Cluster or Powertrain Control Modules have set DTC's which may affect Engine Cooling operation are present.
  3. 4:  The presence of DTCs which begin with "U" indicate some other module is not communicating. The specified procedure will compile all the available information before tests are performed.
Diagnostic System Check - Engine Cooling

Step Action Yes No
1 Install a scan tool.
Does the scan tool power up?
Go to Step 2  Go to Scan Tool Does Not Power Up in Data Link Communications
  1. Turn ON the ignition, with the engine OFF.
  2. Attempt to establish communication with the following control modules:
    • Instrument Cluster
    • Powertrain Control Module
Does the scan tool communicate with the control modules?
Go to Step 3  Go to Scan Tool Does Not Communicate with Class 2 Device in Data Link Communications
Select the powertrain control module display DTCs function on the scan tool.
Does the scan tool display any DTCs?
Go to Step 4  Go to Symptoms - Engine Cooling 
Does the scan tool display any DTCs which begin with a "U"? Go to Scan Tool Does Not Communicate with Class 2 Device in Data Link Communications Go to Diagnostic Trouble Code (DTC) List