GM Service Manual Online
For 1990-2009 cars only

Step

Action

Yes

No

DEFINITION: The coolant heater does not warm the engine coolant properly.

1

Did you perform the necessary inspections?

Go to Step 2

Go to Symptoms - Engine Cooling

2

Test the engine coolant heater power supply cord for an open or short to ground. Refer to Circuit Testing in Wiring Systems.

Did you find a condition?

Go to Step 3

Go to Step 4

3

Replace the engine coolant heater power supply cord. Refer to Coolant Heater Cord Replacement .

Did you complete the replacement?

Go to Step 6

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4

Inspect for poor connections at the harness connector of the engine coolant heater. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs in Wiring Systems.

Did you find and correct the condition?

Go to Step 6

Go to Step 5

5

Replace the engine coolant heater. Refer to Coolant Heater Replacement .

Did you complete the replacement?

Go to Step 6

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6

Operate the system in order to verify the repair.

Did you correct the condition?

System OK

Go to Step 2