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 Circuit High VoltageDiagnostic Fault Information
Circuit | Short to Ground | Open/High Resistance | Short to Voltage | Signal Performance |
|---|---|---|---|---|
Fuel Level Sensor Reference Voltage Circuit | P0462 P2067 | -- | -- | P0461 P2066 or P2636 |
Fuel Level Sensor 1 Signal Circuit Fuel Level Sensor 2 Signal Circuit | P0462 P2067 | P0463 P2068 P0464 | P0463 P2068 | P0461 P2066 or P2636 |
Fuel Level Sensor Low Reference Circuit | -- | P0463 P2068 P0464 | P0463 P2068 | P0461 P2066 or P2636 |
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 serial data circuit to the instrument cluster in order to control the fuel gage.
Conditions for Running the DTC
| • | The ignition is ON. |
| • | The system voltage is between 11-18 volts. |
Conditions for Setting the DTC
| • | The secondary fuel level sensor voltage is greater than 3.5 volts. |
| • | The above condition is present for greater than 24 seconds. |
Action Taken When the DTC Sets
| • | The fuel gage defaults to empty. |
| • | The driver information center (DIC) displays 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. |
Reference Information
Schematic Reference
| • | Engine Controls Schematics for the 6.0L engine |
| • | Engine Controls Schematics for the 7.0L engine |
Connector End View Reference
| • | Engine Control Module Connector End Views for the 6.0L engine |
| • | Engine Control Module Connector End Views for the 7.0L engine |
Electrical Information Reference
Scan Tool Reference
Circuit/System Verification
Ignition ON, observe the scan tool Fuel Level Sensor Right Tank parameter. The reading should be between 0.9 V-3.0 V.
Circuit/System Testing
- Ignition OFF, disconnect the harness connector at the secondary fuel level sensor.
- Ignition OFF, test for less than 1 ohm of resistance between the low reference circuit terminal 4 and ground.
- Ignition ON, install a 3A fused jumper wire between the signal circuit terminal 1 and the low reference circuit terminal 4. Verify the scan tool Fuel Level Sensor Right Tank parameter is less than 0.4 volt.
- If all circuits test normal, perform the fuel level sensor component test before replacing the secondary fuel level sensor.
| ⇒ | If greater than 1 ohm, test the low reference circuit terminal 4 for a short to voltage or an open/high resistance. If the circuits tests normal, replace the ECM. |
| ⇒ | If greater than the specified, test the signal circuit terminal 1 for a short to voltage or an open/high resistance. If the circuit tests normal, replace the ECM. |
Component Testing
- Ignition OFF, disconnect the harness connector at the secondary fuel level sensor.
- While sweeping the secondary 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 1 and the low reference terminal 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 - Left Side for the 6.0L engine |
| • | Fuel Level Sensor Replacement - Left Side for the 7.0L engine |
| • | Control Module References for the ECM replacement, setup, and programming |
