Diagnostic System Check - Engine Cooling

Install a scan tool. If the scan tool powers up, go to next step. If the scan tool does not power up, go to SCAN TOOL DOES NOT POWER UP under SYSTEM TESTS in appropriate BODY CONTROLS MODULE article in ACCESSORIES & EQUIPMENT.
NOTE: 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.
Turn ON the ignition, with the engine OFF. Attempt to establish communication with the following control modules:
- Instrument cluster.
- Powertrain control module (PCM).
If the scan tool communicates with the control modules, go to next step. If the scan tool does not communicate with the control modules, go to SCAN TOOL DOES NOT COMMUNICATE WITH CLASS 2 DEVICE under SYSTEM TESTS in appropriate BODY CONTROLS MODULE article in ACCESSORIES & EQUIPMENT.
NOTE: This step determines if the instrument cluster or PCM have set DTC's which may affect engine cooling operation are present.
Select the powertrain control module display DTCs function on the scan tool. If the scan tool displays any DTCs, go to next step. If the scan tool does not display any DTCs, go to SYMPTOMS - ENGINE COOLING under TROUBLE SHOOTING.
NOTE: The presence of DTCs which begin with "U" indicate some other module is not communicating.
If the scan tool displays any DTCs which begin with a "U", go to SCAN TOOL DOES NOT COMMUNICATE WITH CLASS 2 DEVICE under SYSTEM TESTS in appropriate BODY CONTROL MODULES article in ACCESSORIES & EQUIPMENT. If the scan tool does not display any DTCs which begin with a "U", go to DIAGNOSTIC TROUBLE CODE DEFINITIONS table.