GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 Chevrolet 🢒 2008 🢒 Kodiak C-Series (Conventional) C4/C5 🢒 Safety and Security 🢒 Supplemental Inflatable Restraints 🢒 DTC P2066

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 Performance

Diagnostic Fault Information

Circuit

Short to Ground

High Resistance

Open

Short to Voltage

Signal Performance

Fuel Level Sensor Signal Secondary

P2067

1

P2068

P2068

P2066

Fuel Level Sensor Low Reference

--

1

P2068

P2068

P2066

1. Fuel Gage Inaccurate or Inoperative

Circuit Description

The engine control module (ECM)/powertrain control module (PCM) monitors the signal circuits of the primary fuel level sender and the secondary fuel level sender in order to determine fuel level. Each sender consists of a variable resistor that changes resistance based on fuel level in both tanks. The ECM/PCM monitors the voltage across both sender resistances in order to determine the fuel level. The ECM/PCM uses the signal circuits of the primary fuel level sender and the secondary fuel level sender in order to calculate the total remaining fuel, in percent. The ECM/PCM sends the fuel level percent via serial data circuit to the instrument cluster in order to control the gage.

This diagnostic tests for a stuck secondary fuel level sensor signal. The ECM/PCM sets this DTC if the secondary 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 ignition is ON.

Conditions for Setting the DTC

The ECM/PCM does not detect a change in the secondary fuel level of at least 3 L (0.79 gal) over a distance of 320 km (200 miles).

Action Taken When the DTC Sets
    • The fuel gage defaults to empty.
    • The ECM/PCM records the operating conditions at the time that the diagnostic test fails. The ECM/PCM 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.

Reference Information

Schematic Reference

Instrument Cluster Schematics

Connector End View Reference

Component Connector End Views

Description and Operation

Instrument Cluster Description and Operation

Electrical Information Reference

    •  Circuit Testing
    •  Connector Repairs
    •  Testing for Intermittent Conditions and Poor Connections
    •  Wiring Repairs

Scan Tool Reference

Control Module References for scan tool information

Component Testing
  1. Ignition OFF, remove the secondary fuel level sender and verify there are no obstructions interfering with the fuel level sender.
    2. ⇒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 4 and the low reference terminal 2.
    4. ⇒If not within the specified range, replace the secondary fuel level sensor.

Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

    •  Fuel Level Sensor Replacement for the 6.6L engine
    •  Fuel Sender Assembly Replacement for the 7.8L engine
    •  Fuel Sender Assembly Replacement for the 8.1L engine
    •  Control Module References for the ECM/PCM replacement, setup, and programming