• | 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. |
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 |
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.
The ignition is ON.
• | The secondary fuel level signal is less than 0.5 volts. |
• | The above condition is present for greater than 20 seconds. |
• | 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. |
• | 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. |
Instrument Cluster Description and Operation
Control Module References for scan tool information.
Ignition ON, observe the scan tool Fuel Level Sensor parameter. The reading should be between 0.9-3.0 volts.
⇒ | If less than the specified value, test the signal circuit terminal 4 for a short to ground. If the circuit tests normal, replace the ECM/PCM. |
⇒ | If not within the specified range, replace the secondary fuel level sensor. |
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 |