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 VoltageDiagnostic 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. The fuel level information is also used for misfire and evaporative emission (EVAP) diagnostics.
Conditions for Running the DTC
The ignition is ON.
Conditions for Setting the DTC
| • | The secondary fuel level signal is greater than 4.5 volts. |
| • | The above condition is present for greater than 20 seconds. |
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. |
| • | The ECM/PCM receives the clear code command from the scan tool. |
Reference Information
Schematic Reference
Connector End View Reference
Description and Operation
Instrument Cluster Description and Operation
Electrical Information Reference
Scan Tool Reference
Control Module References for scan tool information
Circuit/System Verification
Ignition ON, observe the scan tool Fuel Level Sensor parameter. The reading should be between 0.9-3.0 volts.
Circuit/System Testing
- Ignition OFF, disconnect the harness connector at the secondary fuel level sensor.
- Ignition OFF, test for less than 1 ohm between the low reference circuit terminal 2 and ground.
- Ignition ON, install a 3-amp fused jumper wire between the signal circuit terminal 4 and the low reference circuit terminal 2. Verify the scan tool Fuel Level Sensor Rear Tank parameter display is less than 0.5 volts.
- If all circuits test normal, test or replace the secondary fuel level sensor.
| ⇒ | 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/PCM. |
| ⇒ | If greater than the specified range, test the signal circuit for a short to voltage or an open/high resistance. If the circuit tests normal, replace the ECM/PCM. |
Component Testing
- Ignition OFF, remove the secondary fuel level sender.
- 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 4 and the low reference terminal 2.
| ⇒ | 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 |
