For 1990-2009 cars

# Coolant Temperature Telltale Inoperative and/or Coolant Gauge Inoperative - kw light lamp hot instrument cluster IP IPC

Subject: | Coolant Temperature Telltale Inoperative and/or Coolant Gauge Inoperative

Models: | .

The following diagnosis might be helpful if the vehicle exhibits the symptom described in the PI.

### Condition/Concern:

The coolant temperature telltale is inoperative, on at all times or flashing and/or the coolant temperature gauge is inoperative (may indicate full hot) or fluctuating.

### Recommendation/Instructions:

Service information shows the PCM as directly controlling the coolant gauge and telltale functions in the cluster. This information is not accurate. The PCM provides information to the BCM for these functions via serial data (Class II). The BCM then controls the operation of the coolant gauge and telltale via serial data to the I/P cluster. If the engine coolant temperature and transaxle fluid temperature sensors show normal readings and no related codes are stored in the PCM, suspect a BCM fault and replace the controller.

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Please follow this diagnosis process thoroughly and complete each step. If the condition exhibited is resolved without completing every step, the remaining steps do not need to be performed. If these steps do not resolve the condition, please contact GM TAC for further diagnostic assistance.

### Models:

(00, 01, 02 Saturn S-Series)

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