GM Service Manual Online
For 1990-2009 cars only

DTC P2067 5.7L

DTC Descriptor

DTC P2067: Fuel Level Sensor 2 Low Voltage

Diagnostic Fault Information

Perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure.

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

P2068

P2066

Fuel Level Sensor Low Reference Circuit

--

P2068

P2068

P2066

Circuit/System Description

The primary (left) fuel level sender and the secondary (right) fuel level sender changes resistance based on fuel level. The powertrain control module (PCM) monitors the signal circuits of the primary (left) fuel level sender and the secondary (right) fuel level sender in order to determine the fuel level. When the fuel tank is full, the resistances of both fuel level senders are high and the PCM senses a high signal voltage on both the signal circuits of the primary (left) fuel level sender and the secondary (right) fuel level sender. When the fuel tanks are empty, the resistances of the fuel level senders are low and the PCM senses a low signal voltage. The PCM uses the signal circuits of the primary (left) fuel level sender and the secondary (right) fuel level sender in order to calculate the percentage of remaining fuel in the tank. The PCM sends the fuel level percentage via 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 ON.

Conditions for Setting the DTC

    • The secondary sender output is less than 0.5 volt.
    • The above condition is present for greater than 20 seconds.

Action Taken When the DTC Sets

    • The fuel gage defaults to empty.
    • The driver information center (DIC) illuminates the FUEL LEVEL LOW message.
    • The PCM records the operating conditions at the time that the diagnostic test fails. The 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.
    • The PCM receives a clear code command from the scan tool.

Reference Information

Schematic Reference

    •  Instrument Cluster Schematics
    •  Engine Controls Schematics for the 5.7L engine

Connector End View Reference

    •  Instrument Panel, Gages, and Console Connector End Views
    •  Powertrain Control Module Connector End Views for the 5.7L engine

Description and Operation

Fuel Gage Description and Operation

Electrical Information Reference

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

Scan Tool Reference

Scan Tool Data List

Circuit/System Verification

With the scan tool installed and the ignition ON, the Fuel Tank Level Remaining parameter in the PCM EVAP Data List should indicate a value at or lower than 4 percent.

Circuit/System Testing

  1. Ignition OFF, disconnect the harness connector at the secondary fuel level sensor.
  2. Ignition ON, scan tool installed, verify that the scan tool Fuel Tank Level Remaining parameter is greater than 98 percent.
  3. If less than 98 percent, test the secondary signal circuit for a short to ground. If the circuit tests normal, replace the PCM.
  4. If all circuits test normal, perform the fuel level sensor component test before replacing the secondary (left) fuel level sensor.

Component Testing

  1. Ignition OFF, disconnect the harness connector at the secondary (right) fuel level sensor.
  2. While sweeping the secondary (right) fuel level sensor through its full range of motion, test for a minimum value less than 41 ohms and a maximum value greater than 119 ohms of resistance between signal terminal A and the low reference terminal D.
  3. If not within the specified range, replace the secondary (right) fuel level sensor.

Repair Instructions

    •  Secondary Fuel Tank Module Replacement for the 5.7L engine
    •  Control Module References for the PCM replacement, setup, and programming

DTC P2067 2.8L and 3.6L

DTC Descriptor

DTC P2067: Fuel Level Sensor 2 Low Voltage

Diagnostic Fault Information

Perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure.

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

P2068

P2066

Circuit/System Description

The primary (left) fuel level sender and the secondary (right) fuel level sender changes resistance based on fuel level. The engine control module (ECM) monitors the signal circuits of the primary (left) fuel level sender and the secondary (right) fuel level sender in order to determine the fuel level. When the fuel tank is full, the resistances of both fuel level senders are high and the ECM senses a high signal voltage on both the signal circuits of the primary (left) fuel level sender and the secondary (right) fuel level sender. When the fuel tanks are empty, the resistances of the fuel level senders are low and the ECM senses a low signal voltage. The ECM uses the signal circuits of the primary (left) fuel level sender and the secondary (right) fuel level sender in order to calculate the percentage of remaining fuel in the tank. The ECM sends the fuel level percentage via serial data circuit to the instrument cluster in order to control the fuel gage.

Conditions for Running the DTC

    • The engine is running.
    • The system voltage is between 10-18 volts.

Conditions for Setting the DTC

    • The secondary sender output is less than 0.25 volt.
    • The secondary fuel level sensor signal range is about 5 percent.
    • The above condition is present for greater than 60 seconds.

Action Taken When the DTC Sets

    • The fuel gage defaults to empty.
    • The driver information center (DIC) illuminates the FUEL LEVEL LOW message.
    • 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

    •  Instrument Cluster Schematics
    •  Engine Controls Schematics for the 3.6L engine
    •  Engine Controls Schematics for the 2.8L engine

Connector End View Reference

    •  Instrument Panel, Gages, and Console Connector End Views
    •  Engine Control Module Connector End Views for the 3.6L engine
    •  Engine Control Module Connector End Views for the 2.8L engine

Description and Operation

Fuel Gage Description and Operation

Electrical Information Reference

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

Scan Tool Reference

Scan Tool Data List

Circuit/System Verification

With the scan tool installed and the ignition ON, the Fuel Tank Level Remaining parameter in the ECM EVAP Data List should indicate a value at or lower than 4 volts.

Circuit/System Testing

  1. Ignition OFF, disconnect the harness connector at the fuel level sensor.
  2. Ignition ON, scan tool installed, verify that the scan tool Fuel Tank Level Remaining parameter is greater than 4.5 volts.
  3. If less than 4.5 volts, test the secondary tank signal circuit for a short to ground. If the circuit tests normal, replace the ECM.
  4. If all circuits test normal, perform the fuel level sensor component test before replacing the secondary (left) fuel level sensor.

Component Testing

  1. Ignition OFF, disconnect the harness connector at the secondary (right) fuel level sensor.
  2. While sweeping the secondary (right) fuel level sensor through its full range of motion, test for a minimum value less than 41 ohms and a maximum value greater than 119 ohms of resistance between signal terminal A and the low reference terminal D.
  3. If not within the specified range, replace the secondary (right) fuel level sensor.

Repair Instructions

    •  Secondary Fuel Tank Module Replacement for the 3.6L engine
    •  Secondary Fuel Tank Module Replacement for the 2.8L engine
    •  Control Module References for the ECM replacement, setup, and programming