GM Service Manual Online
For 1990-2009 cars only

Step

Action

Value(s)

Yes

No

DEFINITION: The engine temperature lamp comes on and stays on, the temperature gauge shows hot or coolant overflows from the coolant recovery reservoir onto the ground while the engine is running.

1

Check for a missing or damaged radiator upper baffle and/or center air deflector.

Is the baffle or deflector missing or damaged?

--

Go to Step 8

Go to Step 2

2

Check for a loss of coolant.

Is there a loss of coolant?

--

Go to Step 3

Go to Step 4

3

Fill the system to the specified level. Refer to Loss of Coolant .

Does the engine overheat?

--

Go to Step 4

System OK

4

Check for low coolant protection. Refer to Coolant Concentration Testing .

Is the coolant to the correct correction?

--

Go to Step 5

Go to Step 8

5

Check for a loss of system pressure. Refer to Cooling System Leak Testing .

Is there a loss of system pressure?

--

Go to Step 8

Go to Step 6

6

Check for a faulty engine coolant temperature (ECT) sensor. Refer to DTC P0117 Engine Coolant Temperature (ECT) Sensor Circuit Low Voltage and DTC P0118 Engine Coolant Temperature (ECT) Sensor Circuit High Voltage in Engine Controls - 3.5L.

Is the sensor operating properly?

--

Go to Step 7

Go to Step 8

7

Check for a cracked coolant recovery reservoir or a leaking hose. Refer to Loss of Coolant .

Is the reservoir cracked or is the hose leaking?

--

Go to Step 8

Go to Step 3

8

Repair or install new parts as necessary, then retest.

Does the engine overheat?

--

Go to Step 9

System OK

9

Check for incorrect drive belt tension. Refer to Drive Belt Replacement in Engine Mechanical - 3.5L.

Is the belt to the correct tension?

--

Go to Step 10

Go to Step 8

10

Correct for damaged water pump driveshaft.

Is the water pump driveshaft damaged or is the seal leaking?

--

Go to Step 8

Go to Step 11

11

Check for obstructed radiator air flow or bent radiator fins.

Is the radiator air flow obstructed?

--

Go to Step 8

Go to Step 12

12

Check for blocked cooling system passages.

Are the cooling system passages blocked?

--

Go to Step 8

Go to Step 13

13

Check for improper direction or inoperative cooling fans. Refer to Engine Coolant Fan Motor Replacement .

Are the cooling fans and the motors operating correctly?

--

Go to Step 14

Go to Step 8

14

Check the thermostat. Refer to Thermostat Diagnosis .

Is the thermostat stuck in the closed position?

--

Go to Step 15

Go to Step 16

15

Replace the thermostat. Refer to Engine Coolant Thermostat Replacement .

Does the engine overheat?

--

Go to Step 16

System OK

16

Check for faulty water pump. Refer to Water Pump Replacement .

Are the impeller blades broken or eroded?

--

Go to Step 8

Go to Step 17

17

Check the radiator cooling capacity.

Is the proper sized radiator being used on the vehicle?

--

Go to Step 3

Go to Step 18

18

Consult the current parts catalog. If necessary, replace the radiator. Refer to Radiator Replacement .

Is the repair complete?

--

System OK

--