P2636
DTC P2636
Diagnostic Instructions
* Perform the Diagnostic System Check - Vehicle Diagnostic System Check - Vehicle prior to using this diagnostic procedure.
* Review Strategy Based Diagnosis Strategy Based Diagnosis for an overview of the diagnostic approach.
* Diagnostic Procedure Instructions Diagnostic Procedure Instructions provides an overview of each diagnostic category.
DTC Descriptor
DTC P2636
-
Fuel Transfer Pump Flow Insufficient
Circuit/System Description
The fuel transfer pump is located on the left frame rail between the fuel tanks. The engine control module (ECM) provides ignition positive voltage to the coil side of the fuel transfer pump relay. The ECM energizes the fuel transfer pump relay, which applies power to the fuel transfer pump. Fuel is transferred from the rear fuel tank to the front fuel tank in order to ensure all of the usable fuel volume is available to the engine. If the ECM commands the transfer fuel pump ON and a predetermined change in the front and rear fuel level sensors does not occur, this DTC sets.
Conditions for Running the DTC
* DTCs P0461, P0462, P0463, P0500, P2067, or P2068 are not set.
* The engine is running.
* The vehicle speed is 0 km/h (0 mph).
* The primary fuel level is less than 25 liters (6.6 gallons).
* The secondary fuel level is between 3-10 liters (0.8-2.6 gallons).
* The above conditions are present for 20 seconds before the fuel transfer pump is commanded ON.
* The fuel transfer pump is commanded ON for greater than 120 seconds.
Conditions for Setting the DTC
The ECM detects a primary fuel level increase and a secondary fuel level decrease of less than 2.6 liters (0.70 gallons) each, within 120 seconds.
Action Taken When the DTC Sets
DTC P2636 is a Type C DTC.
Conditions for Clearing the DTC
* DTC P2636 is a Type C DTC.
* The fuel gauge will default to empty when this DTC sets.
Diagnostic Aids
* When outside temperatures are below 0° C (32° F), the fuel tank pickup screen may ice over from water in the fuel tank.
* If the ignition is on or the engine is running while fueling the vehicle, this DTC may set.
Reference Information
Schematic Reference
Engine Controls Schematics (LGH or LML) [1][2]Electrical Diagrams
Connector End View Reference
Component Connector End Views 1-2 Shift Solenoid (SS) Valve (M30)
Electrical Information Reference
* Circuit Testing Circuit Testing
* Connector Repairs Connector Repairs
* Testing for Intermittent Conditions and Poor Connections Testing for Intermittent Conditions and Poor Connections
* Wiring Repairs Wiring Repairs
DTC Type Reference
Powertrain Diagnostic Trouble Code (DTC) Type Definitions Powertrain Diagnostic Trouble Code (DTC) Type Definitions
Scan Tool Reference
Control Module References Control Module References for scan tool information
Special Tools
J 43244 Relay Puller Pliers
Circuit/System Verification
1. If DTC P2632 is set, refer to Diagnostic Trouble Code (DTC) List - Vehicle Diagnostic Trouble Code (DTC) List - Vehicle.
2. Ignition ON, command the fuel transfer pump relay ON and OFF with a scan tool. You should hear and feel the fuel pump relay click with each command. The fuel transfer pump should operate when commanded ON.
3. Operate the vehicle within the Conditions for Running the DTC. You may also operate the vehicle within the conditions that you observed from the Freeze Frame/Failure Records data.
Circuit/System Testing
Note:
* You must perform the Circuit/System Verification before proceeding with Circuit/System Testing.
* If the fuel level is not between 25-50 percent, add 19 L (5 gal) in order to perform this diagnostic procedure. If the fuel level is not within this range, misdiagnosis will occur.
1. Ignition OFF, disconnect the fuel transfer pump relay.
2. Ignition ON, verify a test lamp illuminates between the positive voltage supply circuit of the fuel pump relay and ground.
• If the test lamp does not illuminate, test the positive voltage supply circuit for an open.
3. Connect a fused jumper wire between the positive voltage supply circuit of the fuel transfer pump relay and the voltage supply circuit of the fuel pump. The fuel transfer pump should operate.
• If the fuel transfer pump did not operate, test the voltage supply circuit of the fuel transfer pump and the ground circuit of the fuel transfer pump for an open.
• If the positive voltage supply circuit fuse opens, test the voltage supply circuit of the fuel transfer pump for a short to ground.
• If all circuits tested normal, replace the fuel transfer pump.
4. With the fused jumper still connected , observed the Fuel Level sensor voltage parameter with a scan tool. The rear fuel level voltage should increase as the pump is operating.
• If the fuel level voltage did not increased, inspect the fuel lines and the fuel sender for a restriction at the rear fuel tank.
5. Remove the fused jumper and disconnect the outlet hose from the fuel transfer pump.
6. Connect a section of rubber hose with a clamp to the outlet port of the fuel transfer pump. Insert the other end of the hose into an approved container to measure more than 4 liters (1.06 gallons) of fuel.
7. Operate the fuel transfer pump for 2 minutes and measure the fuel in the container. There should be greater than 2.6 liters (0.70 gallons) of fuel.
• If the fuel volume less than the specified value, replace the fuel transfer pump.
Repair Instructions
Perform the Diagnostic Repair Verification Verification Tests after completing the diagnostic procedure.
Fuel Pump Replacement (Auxiliary Tank, Balance) Fuel Pump Replacement (Auxiliary Tank, Balance)