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 provide an overview of each diagnostic category.
DTC Descriptor
DTC P2636
- Fuel Pump 2 Flow Insufficient
Circuit/System Description
The secondary fuel pump is located in the rear fuel tank. The secondary fuel pump is powered by a secondary fuel pump relay. 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 primary fuel pump. The secondary fuel pump relay is controlled by the engine control module (ECM). If the engine is running the secondary fuel pump is normally ON.
Conditions for Running the DTC
* The engine is running.
* The vehicle speed is 0 km/h (0 mph).
* The ignition voltage is between 11-32 volts.
* The transfer pump is activated.
* A slosh delay of 20 seconds has passed.
* DTC P2636 runs continuously when the above conditions are met.
Conditions for Setting the DTC
The ECM does not detect a change of 3 L (0.7925 gal), in both the primary and the secondary fuel level sensors, with the secondary pump commanded ON for 200 seconds.
Action Taken When the DTC Sets
DTC P2636 is a Type B DTC.
Conditions for Clearing the MIL/DTC
DTC P2636 is a Type B DTC.
Reference Information
Schematic Reference
Engine Controls Schematics [1][2]Electrical Diagrams
Connector End View Reference
Component Connector End Views Connector End Views By Name
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. Verify that DTC P2632 is not set.
• 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 Pump Relay 2 ON and OFF with a scan tool. You should hear and feel the fuel pump relay click with each command. The secondary fuel pump should operate when commanded ON.
3. Operate the vehicle within the Conditions for Running the DTC to verify the DTC does not reset. 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 may occur.
1. Ignition OFF, disconnect the secondary fuel pump relay.
2. Ignition ON, verify that a test lamp illuminates between the secondary fuel pump relay supply voltage circuit terminal 30 and ground.
• If the test lamp does not illuminate, test the supply voltage circuit for a short to ground or open/high resistance. If the circuit tests normal and the supply voltage fuse is open, test the component control circuit terminal 87 for a short to ground.
3. Ignition OFF, disconnect the harness connector at the secondary fuel tank fuel pump module.
4. Test for less than 10 ohms between the secondary fuel pump ground circuit terminal A and ground.
• If greater than the specified range, test the ground circuit for an open/high resistance.
5. Connect the harness connector at the secondary fuel tank fuel pump module.
6. Ignition ON, connect a 15 A fused jumper between the supply voltage circuit terminal 30 and the component control circuit terminal 87. Verify the secondary fuel pump is activated.
• If the secondary fuel pump does not activate, test the component control circuit for an open/high resistance. If the circuit tests normal, replace the secondary fuel tank fuel pump module.
7. With the fused jump connected and the secondary fuel pump activated, observed the Fuel Level Sensor Rear Tank voltage parameter with a scan tool. The fuel level voltage should increase as the pump is operating.
• If the fuel level voltage did not increased, inspect the fuel lines and the secondary fuel tank fuel pump module for a restriction. If no restrictions are present, replace the secondary fuel tank fuel pump module.
Repair Instructions
Perform the Diagnostic Repair Verification Verification Tests after completing the diagnostic procedure.
* Fuel Tank Fuel Pump Module Replacement (2500 LWB - 98.4L (26 gal) Tank Front) Service and RepairFuel Tank Fuel Pump Module Replacement (1500 SWB - 98.4L (26 gal) Tank + E85) Service and RepairFuel Tank Fuel Pump Module Replacement (1500 Series) Service and RepairFuel Tank Fuel Pump Module Replacement (2500 LWB - 43.5L (11.5 gal) Tank Rear) Service and RepairFuel Tank Fuel Pump Module Replacement (1500 LWB - 117.3L (31 gal) Tank + E85) Service and Repair
* Relay Replacement (Within an Electrical Center) Relay Replacement (Within an Electrical Center)Relay Replacement (Attached to Wire Harness) Relay Replacement (Attached to Wire Harness)
* Control Module References Control Module References for ECM replacement, setup, and programming