GM Service Manual Online
For 1990-2009 cars only

Step

Action

Yes

No

Schematic Reference: Instrument Cluster Schematics

Connector End View Reference: Cooling System Connector End Views

DEFINITION: The low coolant indicator is always on when the key is in the ON position.

1

Did you perform the Diagnostic System Check - Vehicle?

Go to Step 2

Go to Diagnostic System Check - Vehicle in Vehicle DTC Information

2

Check the engine coolant level.

Is the engine coolant level low?

Go to Loss of Coolant

Go to Step 3

3

  1. Turn ON the ignition, with the engine OFF.
  2. With a scan tool, command the instrument cluster indicators ON and OFF.

Does the low coolant indicator lamp turn ON and OFF with each command?

Go to Step 4

Go to Step 5

4

  1. Turn the ignition to the OFF position.
  2. Disconnect the coolant level switch connector.
  3. Connect a 3-amp fused jumper wire between the coolant level signal circuit and the coolant level sensor ground circuit. Refer to Circuit Testing in Wiring Systems.
  4. Start the engine of the vehicle.

Does the low coolant indicator turn OFF after bulb check?

Go to Step 10

Go to Step 5

5

  1. Turn OFF the ignition.
  2. Remove the jumper wire.
  3. Turn the ignition ON.
  4. Measure the voltage from the coolant level signal circuit to the coolant level ground circuit. Refer to Circuit Testing in Wiring Systems.

Does the voltage measure battery voltage?

Go to Step 9

Go to Step 6

6

Measure the voltage from the coolant level sensor signal circuit to a good ground. Refer to Circuit Testing in Wiring Systems.

Does the voltage measure battery voltage?

Go to Step 8

Go to Step 7

7

Test the signal circuit of the coolant level switch for an open or short to ground. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

Go to Step 15

Go to Step 11

8

Repair the open in the ground circuit of the coolant level switch. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Is the repair complete?

Go to Step 15

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9

Inspect for poor connections at the harness connector of the instrument panel cluster (IPC). 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 15

Go to Step 13

10

Inspect for poor connections at the harness connector of the coolant level switch. 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 15

Go to Step 14

11

Inspect for poor connections at the harness connector of the powertrain control module (PCM). 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 15

Go to Step 12

12

Replace the PCM. Refer to Control Module References in Computer/Integrating Systems for replacement, setup, and programming.

Did you complete the repair?

Go to Step 15

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13

Replace the IPC. Refer to Instrument Cluster Replacement .

Did you complete the repair?

Go to Step 15

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14

Replace the coolant level switch. Refer to Radiator Surge Tank Replacement .

Did you complete the replacement?

Go to Step 15

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15

Operate the system in order to verify the repair.

Did you correct the condition?

System OK

Go to Step 2