Fuel Gage

The instrument panel cluster (IPC) displays the fuel level on the analog fuel gage as determined by the powertrain control module (PCM). The PCM monitors the signal circuit of the fuel level sensor. When the fuel level sensor resistance is high, the fuel gage indicates full. When the fuel level sensor resistance is low, the fuel gage indicates empty. The IPC receives a class 2 message from the PCM indicating the filtered fuel level percent. The PCM uses 2 filters for the fuel level percent. The slow filter is used during normal operation. The fast filter is used when the engine is just started or when the vehicle is in Park or Neutral. The fast filter allows the fuel gage to reach the current fuel level quickly. The fuel gage defaults to empty when the following conditions occur:

• The PCM detects a malfunction in the fuel level sensor circuit. Refer to Diagnostic System Check - Vehicle .
• The IPC detects a loss of class 2 communications with the PCM.

Reviewing the fuel system description will further explain how the system functions. Refer to the following procedures:

• Fuel System Description for the 4.3L engine.
• Fuel System Description for the 4.8L, 5.3L, and 6.0L engine.
• Fuel System Description for the 6.6L (LBZ and LLY) engine.
• Fuel System Description for the 6.6L (LMM) engine.