2010 Cadillac Truck Escalade/ESV RWD V8-6.2L Page 2468
overview of the diagnostic approach.
* Diagnostic Procedure Instructions (See: Testing and Inspection/Initial Inspection and Diagnostic Overview/Diagnostic Procedure
Instructions) provides an overview of each diagnostic category.
DTC Descriptor
DTC P2068
- Fuel Level Sensor 2 High Voltage
Diagnostic Fault Information
Circuit/System Description
The primary fuel level sensor and the secondary fuel level sensor change resistance in response to the fuel level. The engine control module (ECM)
monitors the signal circuit of the primary fuel level sensor, the secondary fuel level sensor, and the type of fuel in order to determine the fuel level.
For regular unleaded fuel the ECM monitors a constant signal. When the vehicle has approximately 20% or greater ethanol for E85 fuel
applications, the ECM controls a pulse cycle signal where it monitors the signal and calculates the fuel level percentage only during the on pulse of
approximately 100 ms.
When the fuel tanks are full, the sensor resistances of both fuel level sensors are low and the ECM senses a low signal voltage on both the signal
circuits of the primary fuel level sensor and the secondary fuel level sensor. When the fuel tanks are empty, the resistances of the fuel level sensors
are high and the ECM senses a high signal voltage. The ECM uses the signal circuit of the primary fuel level sensor and the secondary fuel level
sensor 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 gauge.
Conditions for Running the DTC
* The ignition is ON, with the engine running.
* The system voltage is between 9-16 V.
Conditions for Setting the DTC
* The secondary sensor output is greater than 3.5 V.
* The above condition is present for greater than 30 seconds.
Action Taken When the DTC Sets
* The fuel gauge 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.
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
Instrument Cluster Schematics (See: Diagrams/Electrical Diagrams/Instrument Panel, Gauges and Warning Indicators/System Diagram/Instrument
Cluster Schematics)
Connector End View Reference
Component Connector End Views (See: Diagrams/Connector Views)
Description and Operation
Instrument Cluster Description and Operation (See: Instrument Panel, Gauges and Warning Indicators/Description and Operation/Instrument
Cluster)
Electrical Information Reference
* Circuit Testing (See: Testing and Inspection/Component Tests and General Diagnostics/General Electrical Diagnostic Procedures/Circuit
Testing/Circuit Testing)
* Connector Repairs (See: Testing and Inspection/Component Tests and General Diagnostics/General Electrical Diagnostic
