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 Descriptors
DTC P2066: Fuel Level Sensor 2 Circuit PerformanceDTC P2636: Fuel Transfer Pump Flow Insufficient
Diagnostic 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.
Diagnostic Aids
Check if DTC P0461 is also set. Both DTCs P0461 and P2066 may set simultaneously if the vehicle was refueled with the ignition ON or engine RUNNING. Always refuel with the ignition OFF.
Conditions for Running the DTC
P2066
| • | The engine is running. |
| • | No VSS DTCs set. |
P2636
| • | The engine is running. |
| • | DTC P2636 runs continuously once the conditions have been met. |
Conditions for Setting the DTC
P2066
| • | The secondary fuel tank is equal to or greater than 3.3 L (.87 gal) and the ECM does not detect a change in the secondary fuel level of at least 3 L (0.79 gal) over a distance of 100 km (62 mi). |
| • | The ECM detects that the primary fuel tank is less than 28.5 L (7.5 gal) and the secondary fuel tank is more than 3.3 L (.87 gal) and the condition is present for 30 minutes. |
| • | The ECM detects that the primary fuel tank is greater than 28.5 L (7.5 gal) and the secondary fuel tank is less than 3.3 L (.87 gal) over a distance of 200 km (124.2 mi). |
P2636
The ECM detects that the primary fuel tank is less than 28.5 L (7.5 gal) and the secondary fuel tank is more than 3.3 L (.87 gal) and the condition is present for 30 minutes.
Action Taken When the DTC Sets
| • | The fuel gage defaults to empty. |
| • | The malfunction indicator lamp (MIL) will not illuminate. |
| • | 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 Testing
- Ignition OFF, remove the secondary fuel level sender and verify there are no obstructions interfering with the fuel level sender.
- If no interference is present, perform the fuel level sensor component test before replacing the secondary fuel level sensor.
| ⇒ | Repair any fuel level sender interference. |
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 Tank Fuel Pump Module Replacement - Right Side for the 6.0L engine |
| • | Fuel Tank Fuel Pump Module Replacement - Right Side for the 7.0L engine |
| • | Control Module References for the ECM replacement, setup, and programming |
