P2636

Document ID: 1726669

DTC P2636

Diagnostic Instructions
• Perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure. Diagnostic System Check - Vehicle
• Review Strategy Based Diagnosis for an overview of the diagnostic approach. Strategy Based Diagnosis
• Diagnostic Procedure Instructions provide an overview of each diagnostic category. Diagnostic Procedure Instructions

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 9-18 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 liters (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 Electrical Diagrams

Connector End View Reference
• Engine Control Module Connector End Views Connector Views
• Engine Controls Connector End Views Connector Views
• Electrical Center Identification Views Application and ID

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 Diagnostic Trouble Code (DTC) Type Definitions

Scan Tool Reference
• Scan Tool Data List Scan Tool Data List
• Scan Tool Data Definitions Scan Tool Data Definitions 1
• Scan Tool Output Controls Scan Tool Output Controls

Special Tools Required
J 43244 Relay Puller Pliers

Circuit/System Verification
With the ignition ON, engine OFF, command the fuel pump relay ON and OFF several times using the scan tool output control function. You should either hear or feel the relay click with each command.

Circuit/System Testing
1. With the ignition OFF, remove the fuel pump relay from the underhood bussed electrical center.

2. With the ignition ON, engine OFF, probe the control circuit of the fuel pump relay with a test lamp that is connected to a good ground. Command the fuel pump relay ON and OFF with a scan tool.
--> If the test lamp does not turn ON and OFF, test for an open, high resistance, or a short to ground in the fuel pump relay control circuit or an intermittent or a poor connection at the ECM. If the circuit tests normal, replace the control module.
--> If the test lamp remains illuminated with each command, test for a short to voltage in the control circuit of the fuel pump relay, an intermittent or a poor connection at the ECM. If the circuit tests normal, replace the control module.

3. Connect a test lamp between the control circuit of the fuel pump relay and the ground circuit of the fuel pump relay. Command the fuel pump relay ON and OFF with a scan tool. The test lamp should turn ON and OFF with each command.
--> If the test lamp does not turn ON and OFF, repair the open or the high resistance in the ground circuit of the fuel pump relay.
--> If the test lamp does turn ON and OFF, test for an intermittent and for a poor connection at the fuel pump relay. If the circuit tests normal, replace the fuel pump relay.

4. Inspect the fuel pump fuse.
--> If the fuel pump fuse is open, test for a short to ground in the supply voltage circuit of the fuel pump. If the circuit tests normal, replace the fuel pump.

5. With the ignition ON and engine OFF, probe the ignition positive voltage circuit of the fuel pump relay with a test lamp that is connected to a good ground.
--> If the test lamp does not illuminate, repair the open in the ignition positive voltage circuit.

6. Connect a 15A fused jumper wire between the ignition positive voltage circuit of the fuel pump relay and the supply voltage circuit of the fuel pump.
--> If the fuel pump operates, test for an intermittent or poor connection at the fuel pump relay, or a faulty fuel pump relay.
--> If the fuel pump does not operate, test for an open or high resistance in the supply voltage circuit of the fuel pump, an open or high resistance in the ground circuit of the fuel pump, an intermittent or poor connection at the fuel pump module cover, or a faulty fuel pump module.

Repair Instructions
Perform the Diagnostic Repair Verification after completing the diagnostic procedure. Verification Tests
• ECM replacement Service and Repair
• ECM setup, and programming Testing and Inspection
• Fuel Tank Fuel Pump Module Replacement Service and Repair
• Relay Replacement Removal and Replacement