P2066
DTC P2066
Diagnostic Instructions
* Perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure. Initial Inspection and Diagnostic Overview
* 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 Performance
Diagnostic Fault Information
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.
Component Testing
1. Ignition OFF, remove the secondary fuel level sender and verify there are no obstructions interfering with the fuel level sender.
• If any interference is present, repair the fuel sender interference.
2. Ignition OFF, disconnect the harness connector at the secondary fuel level sensor.
3. While sweeping the fuel level sensor through its full range of motion, test for a minimum resistance value of less than 41 ohms and a maximum value greater than 119 ohms between the signal terminal C and the low reference terminal B.
• If not within the specified range, replace the secondary fuel level sensor.
Repair Instructions
Perform the Diagnostic Repair Verification after completing the diagnostic procedure. Verification Tests
* Fuel Level Sensor Replacement (Extended Cab w/26 Gal Tank) Fuel Level Sensor Replacement (Regular Cab w/34 Gal Tank) Fuel Level Sensor Replacement (Regular Cab w/26 Gal Tank) for the 4.3L engine
* Fuel Level Sensor Replacement (15 Reg Cab w/26 gal Tank) Fuel Level Sensor Replacement (15 Ext/Crew Cab w/26 gal Tank) Fuel Level Sensor Replacement (25 Ext/Crew Cab w/26 gal Tank) Fuel Level Sensor Replacement (15/25 Reg/Ext/Crew Cab w/34 gal Tank) Fuel Level Sensor Replacement (35 Reg/Ext/Crew Cab w/34 gal Tank) for the 4.8L, 5.3L, 6.0L, and 6.2L engines
* Fuel Level Sensor Replacement (Cab/Chassis - Rear Tank) for the 6.6L engine