Engine Cooling System: Overview Pontiac Sunfire I

Test Description

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. 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.

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

1. 2. Listen for an audible click when the cooling fan relay operates. Command both the ON and OFF states. Repeat the commands as necessary.
2. 3. Tests for voltage at the coil side of the cooling fan relay. The cool fan fuse supplies power to the cooling fan relay.
3. 4. Verifies that the PCM is providing ground to the cooling fan relay.
4. 5. Tests if ground is constantly being applied to the cooling fan relay.

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Symptoms - Engine Cooling

Important: Review the system operation in order to familiarize yourself with the system functions. Refer to Cooling System Description and Operation .