P2634
DTC P2632-P2634 (Heavy Duty L96)
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 P2632
- Fuel Pump Relay 2 Control Circuit
DTC P2633
- Fuel Pump Relay 2 Control Circuit Low Voltage
DTC P2634
- Fuel Pump Relay 2 Control Circuit High Voltage
Diagnostic Fault Information
Circuit/System Description
The engine control module enables the secondary fuel pump relay when the primary fuel tank is below approximately 50 liters (13.2 gallons) and will run until the primary tank is filled to approximately 70 liters (18.5 gallons) or until the secondary tank is empty.
Conditions for Running the DTC
* The ignition voltage is between 11-32 volts.
* The DTCs run continuously when the above condition is met.
Conditions for Setting the DTC
DTC 2632
The ECM detects the control circuit is open for greater than 2.5 s.
DTC 2633
The ECM detects the control circuit is shorted to ground for greater than 2.5 s.
DTC 2634
The ECM detects the control circuit is shorted to voltage for greater than 2.5 s.
Action Taken When the DTC Sets
DTC P2632, P2633, and P2634 are Type C DTCs.
Conditions for Clearing the MIL/DTC
DTC P2632, P2633, and P2634 are Type C DTCs.
Reference Information
Schematic Reference
Engine Controls Schematics (except L96) [1][2]Electrical DiagramsEngine Controls Schematics (L96) [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
Note: An open or a short to voltage in the control circuit will cause both the Ckt. Open Test Status and the Ckt. Short Volts Test Status parameters to display Fault.
1. Ignition ON, command the Fuel Pump 2 Relay ON and OFF with a scan tool while observing the following control circuit status parameters:
* Fuel Pump 2 Relay Ckt. Short Gnd Test Status
* Fuel Pump 2 Relay Ckt. Open Test Status
* Fuel Pump 2 Relay Ckt. Short Volts Test Status
Each parameter should toggle between OK and Not Run or Not Run and OK.
2. 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
1. Ignition OFF, disconnect the secondary fuel pump relay.
2. Ignition ON, verify that a test lamp illuminates between the ground circuit terminal 85 and B+.
• If the test lamp does not illuminate, test the ground circuit for a short to voltage or an open/high resistance.
3. Verify that a test lamp does not illuminate between the ground circuit terminal 85 and the control circuit terminal 86.
• If the test lamp illuminates, test the control circuit for a short to voltage. If the circuit tests normal, replace the K20 engine control module.
4. Remove the test lamp.
5. Command the Fuel Pump 2 Relay ON with a scan tool. Verify the scan tool Fuel Pump Relay 2 Ckt. Short Gnd Test Status parameter is OK.
• If not the specified value, test the control circuit for a short to ground. If the circuit tests normal, replace the K20 engine control module.
6. Install a 3 A fused jumper wire between the secondary fuel pump relay control circuit terminal 86 and the ground circuit terminal 85. Command the fuel pump ON with a scan tool. Verify the scan tool Fuel Pump 2 Relay Ckt. Short Gnd Test Status parameter is Fault.
• If not the specified value, test the control circuit for an open/high resistance. If the circuit tests normal, replace the K20 engine control module.
7. If all circuits test normal, test or replace the secondary fuel pump relay.
Repair Instructions
Perform the Diagnostic Repair Verification Verification Tests after completing the diagnostic procedure.
* 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, programming, and setup.