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Home >> Chevy Truck >> 2013 >> Silverado 3500 4WD V8-6.0L (CNG) >> Repair and Diagnosis >> A L L Diagnostic Trouble Codes ( DTC ) >> Testing and Inspection >> P Code Charts >> P0629

P0629




DTC P0628 or P0629

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 P0628

-
Fuel Pump Relay Control Circuit Low Voltage

DTC P0629

-
Fuel Pump Relay Control Circuit Circuit High Voltage

Diagnostic Fault Information






Circuit/System Description

The engine control module (ECM) enables the fuel pump relay when the ignition switch is turned ON. The ECM will disable the fuel pump relay within 2 seconds unless the ECM detects ignition reference pulses. The ECM continues to enable the fuel pump relay as long as ignition reference pulses are detected. The ECM disables the fuel pump relay within 2 seconds if ignition reference pulses cease to be detected and the ignition remains ON.

Conditions for Running the DTC

* The engine speed is greater than 0 RPM.

* The ignition voltage is between 11-32 volts.

* The DTCs run continuously when the conditions above are met.

Conditions for Setting the DTC

* The ECM detects that the commanded state of the driver and the actual state of the control circuit do not match.

* The above condition is met for at least 8 out of 10 test cycles.

Action Taken When the DTC Sets

DTCs P0628 and P0629 are Type B DTCs.

Conditions for Clearing the MIL/DTC

DTCs P0628 and P0629 are Type B 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)

Description and Operation

Fuel System Description Fuel System Description

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. Attempt to start the engine. Observe the DTC information with a scan tool. DTC P0628 or P0629 should not set.

2. Ignition ON, command the fuel pump ON and OFF with a scan tool while observing the following control circuit status parameters:

* Fuel Pump Relay Ckt. Short Gnd. Test Status

* Fuel Pump Relay Ckt.Open Test Status

* Fuel Pump Relay Ckt. Short Volts Test Status

Each parameter should toggle between OK and Not Run or Not Run and OK.

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

1. Ignition OFF, disconnect the KR23A 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 relay ON with a scan tool. Verify the scan tool Fuel Pump Relay Ckt. Short Gnd. Test Status parameter is OK.

• If not the specified value, test the fuel pump relay control circuit for a short to ground. If the circuit tests normal, replace the K20 engine control module.

6. Install a 3A fused jumper wire between the 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 Relay Ckt. Short Gnd. Test Status parameter is Fault.

• If not the specified value, test the fuel pump relay 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 KR23A fuel pump relay.

Component Testing

1. Ignition OFF, disconnect the KR23A fuel pump relay.

2. Test for 70-110 ohms between terminal 85 and 86

• If not within the specified range, replace the KR23A fuel pump relay.

3. Test for infinite resistance between the following terminals:

* 30 and 86

* 30 and 87

* 30 and 85

* 85 and 87

• If not the specified value, replace the KR23A fuel pump relay.

4. Connect a 3 A fused jumper wire between relay terminal 86 and B+. Connect a jumper wire between relay terminal 85 and ground. Test for less than 2 ohms between terminals 30 and 87.

• If greater than the specified range, replace the KR23A 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 Engine Control Module replacement, programing, and setup.

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