GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 Chevrolet 🢒 2008 🢒 Silverado - 4WD 🢒 DTC 🢒 DTC P2068

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 P2068: Fuel Level Sensor 2 High Voltage

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/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 the serial data circuit to the instrument cluster in order to control the fuel gage.

Conditions for Running the DTC
    • The ignition is ON, with the engine running.
    • The system voltage is between 9-16 volts.

Conditions for Setting the DTC
    • The secondary sensor output is greater than 3.5 volts.
    • The above condition is present for greater than 30 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.

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

Circuit/System Verification

Ignition ON, verify the scan tool Fuel Tank Level Remaining parameter is between 4-98 percent.

Circuit/System Testing
  1. Ignition OFF, disconnect the harness connector at the secondary fuel level sensor.
  2. Ignition OFF, test for less than 1 ohm between the low reference circuit terminal B and ground.
    3. ⇒If greater than the specified range, test the low reference circuit for a short to voltage or an open/high resistance. If the circuit tests normal, replace the ECM.
  3. Ignition ON, install a 3-amp fused jumper wire between the secondary signal circuit terminal C and the low reference circuit terminal B. Verify the scan tool Fuel Tank Level Remaining parameter display is greater than 98 percent.
    4. ⇒If less than the specified range, test the secondary signal circuit for a short to voltage or an open/high resistance. If the circuit tests normal, replace the ECM.
  4. If all circuits test normal, test or replace the secondary fuel level sensor.

Component Testing
  1. Ignition OFF, remove the secondary fuel level sender.
  2. 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 secondary signal terminal B and the low reference terminal C.
    3. ⇒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 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 ECM replacement, setup, and programming