Diagnostic Instructions
| • | Perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure. |
| • | Review Strategy Based Diagnosis for an overview of the diagnostic approach. |
| • | Diagnostic Procedure Instructions provides an overview of each diagnostic category. |
DTC Descriptor
DTC P2066: Fuel Level Sensor 2 PerformanceDiagnostic Fault Information
Circuit | Short to Ground | Open/High Resistance | Short to Voltage | Signal Performance |
|---|---|---|---|---|
Fuel Level Sensor Reference Voltage Circuit | P2067 | -- | -- | P2066 |
Fuel Level Sensor Signal Secondary Circuit | P2067 | P2068 1 | P2068 | P2066 |
Fuel Level Sensor Low Reference Circuit | -- | P2068 1 | P2068 | P2066 |
1. Fuel Gage Inaccurate or Inoperative | ||||
Circuit/System Description
The primary fuel level sender and the secondary fuel level sender changes resistance based on fuel level. The engine control module (ECM) monitors the signal circuits of the primary fuel level sender and the secondary fuel level sender in order to determine the fuel level. When the fuel tank is full, the resistances of both fuel level senders are low and the ECM senses a low signal voltage on both the signal circuits of the primary fuel level sender and the secondary fuel level sender. When the fuel tanks are empty, the resistances of the fuel level senders are high and the ECM senses a high signal voltage. The ECM uses the signal circuits of the primary fuel level sender and the secondary fuel level sender in order to calculate the percentage of remaining fuel in the tank. The ECM sends the fuel level percentage via GMLAN serial data circuit to the instrument cluster in order to control the fuel gage. The fuel information is also used for misfire and evaporative emission (EVAP) diagnostics.
This diagnostic tests for a stuck fuel level sensor signal. The ECM sets this DTC if the fuel level sensor signal appears to be stuck based on a lack of signal variation expected during normal operation.
Conditions for Running the DTC
| • | The engine is running. |
| • | Fuel level is greater than 32 liters (8.5 gallons). |
Conditions for Setting the DTC
| • | The ECM detects a change in fuel level less than 3 liters (0.8 gallon) over a distance greater than 282 km (175 miles). |
| • | The vehicle is at rest and the primary fuel tank increases by 3 liters (0.8 gallon) and the secondary fuel tank does not decrease by 3 liters (0.8 gallon) when the transfer pump is on greater than 500 seconds. |
Action Taken When the DTC Sets
| • | The fuel gage defaults to empty. |
| • | The low fuel indicator illuminates. |
| • | The ECM records the operating conditions at the time that the diagnostic test fails. The ECM displays the failure information in the Failure Records on the scan tool. |
Conditions for Clearing the DTC
| • | The DTC becomes history when the conditions for setting the DTC are no longer present. |
| • | The history DTC clears after 40 malfunction-free warm-up cycles. |
| • | The ECM receives a clear code command from the scan tool. |
Reference Information
Schematic Reference
| • | Engine Controls Schematics for the 4.3L engine |
| • | Engine Controls Schematics for the 4.8L, 5.3L, 6.0L, and 6.2L engines |
| • | Engine Controls Schematics for the 6.6L engine |
Connector End View Reference
| • | Engine Controls Connector End Views for the 4.3L engine |
| • | Engine Control Module Connector End Views for the 4.8L, 5.3L, 6.0L, and 6.2L engines |
| • | Engine Control Module Connector End Views for the 6.6L engine |
Electrical Information Reference
Scan Tool Reference
Circuit/System Testing
- Ignition OFF, remove the secondary fuel level sender and verify that there is no obstructions interfering with the fuel level sender.
- If no interference is present, replace the secondary fuel level sender.
| ⇒ | If interference is present, remove the obstruction. |
Repair Instructions
Perform the Diagnostic Repair Verification after completing the diagnostic procedure.
| • | Fuel Level Sensor Replacement for the 4.3L engine |
| • | Fuel Level Sensor Replacement for the 4.8L, 5.3L, 6.0L, and 6.2L engines |
| • | Fuel Level Sensor Replacement for the 6.6L engine |
| • | Control Module References for the ECM replacement, setup, and programming |
