GM Service Manual Online
For 1990-2009 cars only

Tools Required

tech 1 Scan Tool

Step

Action

Value(s)

Yes

No

1

  1. Allow the engine to cool.
  2. Start the engine.
  3. Monitor the engine coolant temperature using the tech 1 , or through the heater and A/C control assembly pointer number *-24. Refer to Climate Control Features in HVAC.
  4. Check the radiator inlet hose temperature by feeling the hose while monitoring the engine coolant temperature.

Is the radiator inlet hose cool to the touch until the coolant temperature reaches at least 83°C (181°F)?

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Go to Step 2

Go to step 3

2

The problem is caused from something other than a faulty thermostat.

Is the engine still cold or slow to warm up?

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Go to Engine Fails To Reach Normal Operating Temperature

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3

  1. Install a new engine coolant thermostat. Refer to Engine Coolant Thermostat Replacement .
  2. Recheck the cooling system, using the tech 1 , in order to make sure the system is OK.

Is the engine still cold or slow to warm up?

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--

System OK