• | 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 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.
• | The ignition is ON, with the engine running. |
• | The system voltage is between 11-18 volts. |
• | The secondary sender output is less than 0.5 volt. |
• | The above condition is present for greater than 30 seconds. |
• | 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. |
• | 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, verify the scan tool Fuel Tank Level Remaining parameter is between 4-98 percent.
⇒ | If greater than the specified value, test the secondary signal circuit terminal C for a short to ground. If the circuit tests normal, replace the ECM. |
⇒ | 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 6.0L (LFA) engine |
• | Fuel Level Sensor Replacement for the 4.8L, 5.3L, 6.0L, 6.2L, or 7.0L engine |
• | Control Module References for the ECM replacement, setup, and programming |