Engine Controls/fuel - 6.6l (lgh, Lml) - Repair Instructions GMC Sierra 2500

Scheme 1

Engine Control Module Replacement

Circuit/System Description

The engine control module (ECM) monitors the crankshaft position (CKP) sensor signal under specific conditions to calculate errors caused by slight build tolerance variations in the crankshaft, reluctor wheel, CKP sensor, CKP sensor location, and other related components. The calculated error allows the engine control module (ECM) to accurately compensate for reference period variations. The ECM stores the Crankshaft Position Reluctor Wheel Learn values after a Learn procedure has been performed. If the actual crankshaft position variation is not learned in a given time DTC P0315 will set.

The Crankshaft Position Reluctor Wheel Learn feature is used to enable the ECM's quick learn of build tolerance variations. The stored values are cleared and the ECM stores the newly learned variation values after a Crankshaft Position Reluctor Wheel Learn procedure has been successfully performed.

Diagnostic Aids

1. CKP Pos. Reluctor Wheel Learn - Command: ON; clears the ECM's learn variation values. Press the ON button once during a Learn procedure.
2. CKP Zone 1 Variation Learn Status and CKP Zone 2 Variation Learn Status parameters display: Not Learned - until the ECM attempts to calculate the variation value for the respective RPM range. Active - when the ECM is calculating the variation value for the following engine speeds: Zone 1 - 900 to 1, 449 RPM Zone 2 - 1, 450 to 1, 900 RPM Complete - when the ECM has successfully finished calculating the variation value for the respective RPM ranges. Fail - when the ECM has un-successfully finished calculating the variation value for the respective RPM ranges. More than 1 attempt during an ignition cycle may be needed for the ECM to successfully finish calculating the values.
3. A damaged or defective CKP sensor reluctor /exciter ring may prevent the ECM from successfully completing the Crankshaft Position Reluctor Wheel Learn procedure.
4. Debris between the CKP sensor and the CKP sensor reluctor /exciter ring may prevent the ECM from successfully completing the Crankshaft Position Reluctor Wheel Learn procedure.
5. Monitor the Diesel Particulate Filter (DPF) Regeneration Status parameter, it should remain Inactive when the using the scan tool CKP Pos. Reluctor Wheel Learn procedure.
6. Placing the transmission selector in 4th, 5th, or 6th gear may assist in completing the Learn procedure.
7. The engine RPM will increase when the torque converter clutch (TCC) is un-applied or unlocked.

Note. The Crankshaft Position Reluctor Wheel Learn procedure is required when the following service procedures have been performed, regardless of whether DTC P0315 is set: An engine replacement An ECM replacement An ECM "box swap" with another like vehicle A crankshaft harmonic balancer replacement A crankshaft replacement A flywheel replacement An oil pump drive gear replacement A CKP sensor reluctor /exciter ring replacement A CKP sensor replacement Any engine repairs which disturb the crankshaft to CKP sensor relationship

Note. The Crankshaft Position Reluctor Wheel Learn procedure may have to be performed up to 4 times before the procedure completes successfully. Cycle the ignition to insure the ECM enters a new ignition cycle.

1. Ignition OFF. Verify all vehicle systems are OFF. This may take up to 2 minutes.
2. Ignition ON, engine at idle speed. Observe the DTC information with a scan tool. If a DTC, other than P0300-P0308, P0315, P0263, P0266, P0269, P0272, P0275, P0278, P0281, P0284, or P12B3-P12C1 is set, refer to «Diagnostic Trouble Code (DTC) List - Vehicle»(/gmc/sierra-2500/2012-2012/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures__diagnostic-trouble-code-dtc-list) . If DTC P0315 is set, clear the DTC using a scan tool.
3. Select the CKP Pos. Reluctor Wheel Learn procedure with a scan tool.
4. Use the scan tool to: Command On - CKP Pos. Reluctor Wheel Learn procedure. Command State: On
5. Monitor the following parameters with a scan tool. Verify both parameters display: Not Learned. CKP Zone 2 Variation Learn Status CKP Zone 1 Variation Learn Status If both parameters do not display the indicated status, return to step1.
6. Select a smooth section of roadway to safely perform the following steps.
7. Safely maintain about 2, 500 RPM.
8. When traffic conditions permit, release the accelerator pedal. APP SIGNAL parameter equals 0 %.
9. Verify the scan tool CKP Zone 2 Variation Learn Status parameter displays: Active.
10. Verify the scan tool CKP Zone 2 Variation Learn Status parameter displays: Complete. If the CKP Zone 2 Variation Learn Status parameter does not display the indicated status, repeat steps 7 - 10, up to 3 more times.
11. Safely maintain about 1, 700 RPM.
12. When traffic conditions permit, release the accelerator pedal. APP SIGNAL parameter equals 0 %.
13. Verify the scan tool CKP Zone 1 Variation Learn Status parameter displays: Active.
14. Verify the following scan tool parameters display: Complete. If the CKP Zone 1 Variation Learn Status parameter does not display the indicated status, repeat steps 11 - 14, up to 3 more times. If both CKP Zone 1 Variation Learn Status AND CKP Zone 2 Variation Learn Status parameters do not display the indicated status after completing steps 7 - 10 and 11 - 14 a total of 4 times, refer to «Diagnostic Trouble Code (DTC) List - Vehicle»(/gmc/sierra-2500/2012-2012/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures__diagnostic-trouble-code-dtc-list) for DTC P0315 for further diagnosis.
15. Engine idling, transmission in Park or Neutral.
16. If you were directed to perform this procedure because DTC P0315 failed, verify that DTC P0315 ran and passed. If DTC P0315 failed or did not run, refer to «Diagnostic Trouble Code (DTC) List - Vehicle»(/gmc/sierra-2500/2012-2012/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures__diagnostic-trouble-code-dtc-list) for DTC P0315.
17. Ignition OFF. Verify all vehicle systems are OFF. This may take up to 2 minutes.
18. Perform the «Diagnostic Repair Verification»(/gmc/sierra-2500/2012-2012/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures__diagnostic-repair-verification) after completing the procedure.

Description

The engine control module (ECM) has the ability to learn injector timing performance. With the engine at operating temperature and in closed throttle decel mode, the ECM will pulse each injector individually and measure the changes in rotational speed of the crankshaft using the input from the crankshaft position sensor (CPS). The ECM will run this diagnostic under three different fuel rail pressures for each injector. The ECM will adjust the timing of fuel delivered by each injector to obtain the desired RPM increase. The ECM stores the injector timing value required to increase the crankshaft speed by the desired RPM. If the ECM cannot control an increase in RPM for a given injector the appropriate code will set for that injector. The Fuel Injector Correction Reset must be performed anytime a fuel injector is replaced or an ECM is replaced and the values cannot be transferred from the old ECM.

Conditions for Running the Fuel Injector Correction Reset

Ignition ON, engine OFF.

Reset Procedure

1. Ignition ON, engine OFF, perform the Fuel Injector Correction Reset in Module Setup with a scan tool for each fuel injector that was replaced. If all 8 fuel injectors were replaced, select Reset Injection Value - All Cylinders to reset all the fuel injectors at the same time.
2. Clear the DTCs and return to the diagnostic that referred you here.

The control functions for the fuel injection system are integrated in the engine control module (ECM). Each injector's flow rate information and cylinder position are stored in the memory of both the glow plug control module (GPCM) and the ECM. The fuel injector flow rate programming must be done when any of the following procedures are performed

1. The ECM is replaced
2. The GPCM is replaced
3. Any fuel injectors are replaced

If the ECM does not communicate, the flow rate information can be retrieved from the GPCM. If both control modules fail to communicate, the fuel injector flow rate information, or injection quantity adjustment (IQA) flow rate numbers, will need to be retrieved from each individual injector.

Before Programming A Control Module

Note. DO NOT program a control module unless you are directed by a service procedure or you are directed by a General Motors service bulletin. Programming a control module at any other time will not permanently correct a customers concern.

Ensure the following conditions are met before programming a control module

1. Vehicle system voltage There is no charging system concern. All charging system concerns must be repaired before programming a control module. Battery voltage is between 12-16 V. The battery must be charged before programming the control module if the battery voltage is low. A battery charger is NOT connected to the vehicle battery. Incorrect system voltage or voltage fluctuations from a battery charger may cause programming failure or control module damage. Turn OFF or disable any of the following systems that may put a load on the vehicle battery: Twilight sentinel Interior lights Daytime running lights (DRL)-Applying the parking brake, on most vehicles, disables the DRL system. Refer to the Owner's Manual. HVAC systems Engine cooling fans, etc.
2. The ignition switch is in the proper position-The scan tool prompts you to turn ON the ignition, with the engine OFF. DO NOT change the position of the ignition switch during the programming procedure, unless instructed to do so.
3. All of the following tool connections are secure: The connection at the data link connector (DLC) The voltage supply circuits
4. DO NOT disturb the tool harnesses while programming. If an interruption occurs during the programming procedure, programming failure or control module damage may occur.

Circuit/System Verification

Review the Display ECM & GPCM Inj. Flow Rates parameter with a scan tool. All cylinders should be programmed with a flow rate number. Both the GPCM and the ECM should be programmed with the same flow rate numbers for the corresponding cylinders.

Circuit/System Testing

Note. If the flow rate number is not available in either control module, the numbers will need to be retrieved from each individual injector.

1. With a scan tool installed, enter the vehicle information and select the following options: Engine Control Module Module Setup Injector Flow Rate Programming Display ECM & GPCM Inj. Flow Rates
2. Record all flow rate numbers with the corresponding cylinders from the control modules. NOTE: When installing a new fuel injector, ensure that the IQA data number (1) from the yellow IQA Data Tag, shipped with the new injector, is programmed to the correct cylinder If any injectors are replaced, go to Reprogram Injector Flow Rates parameter and enter the flow rate number of the new injector to the corresponding cylinder. The flow rate numbers will automatically update both control modules. If the ECM was replaced, go to Copy GPCM Inj. Flow Rates to ECM parameter and reprogram the ECM. This will update the ECM with the GPCM flow rate numbers. If the GPCM was replaced or the flow rate numbers are not the same for both modules, go to Copy ECM Inj. Flow Rates to GPCM parameter and reprogram the GPCM. This will update the GPCM with the ECM flow rate numbers. If both control modules were replaced, go to Reprogram Injector Flow Rates parameter and enter the previously recorded flow rate numbers or the numbers retrieved from each individual injector, to the corresponding cylinders.

Note. The ECM and the GPCM must be allowed to completely power down after programming is complete.

1. Install any components or connectors that have been removed or replaced during diagnosis.
2. Perform any adjustment, programming or setup procedures that are required when a component or module is removed or replaced.
3. Turn ON the ignition, with the engine OFF, and clear the DTCs.
4. Disconnect the scan tool and turn OFF the ignition for 2 minutes.
5. If the repair was related to a DTC, duplicate the Conditions for Running the DTC and use the Freeze Frame/Failure Records, if applicable, in order to verify the DTC does not reset. If the DTC resets or another DTC is present, refer to the «Diagnostic Trouble Code (DTC) List - Vehicle»(/gmc/sierra-2500/2012-2012/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures__diagnostic-trouble-code-dtc-list) and perform the appropriate diagnostic procedure. OR If the repair was symptom related, duplicate the conditions under which the customer concern occurred to verify the repair. If the customer concern reoccurs, return to «Symptoms - Vehicle»(/gmc/sierra-2500/2012-2012/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures) and perform the appropriate symptom diagnostic.

A service regeneration of the diesel particulate filter (DPF) is required when the scan tool DPF Accumulation Status parameter displays 30 grams or more of accumulated soot. When commanded, the engine control module (ECM) controls the service regeneration as follows

1. The exhaust system is warmed up for about 8 minutes. Engine speed is slowly increased to 2, 000 RPM and then to 2, 500 RPM.
2. Once the DPF reaches its calibrated regeneration temperature, the ECM maintains engine speed between 2, 000-2, 500 RPM for about 20 minutes until regeneration is complete, is cancelled by the technician, or is aborted due to abnormal conditions.
3. The ECM then slowly decreases engine speed to 1600 RPM, then to 800 RPM, and finally to normal idle speed over a 5 minute period. This is done to allow the DPF to cool down.

The DPF Service Regeneration will be terminated if any of the following conditions occur

1. The DPF Service Regeneration is commanded OFF using the scan tool
2. The scan tool is disconnected from the vehicle

Conditions for Running

The following conditions must be met in order to enable DPF Service Regeneration

1. DTCs P2463 is the only active DTC.
2. The battery voltage is greater than 10 V.
3. The engine speed is between 500-2, 700 RPM.
4. The vehicle speed is 0.
5. The transmission is not in Drive or Reverse
6. The exhaust gas temperature (EGT) sensors 1 is between 20-500°C (68-932°F).
7. The exhaust gas temperature (EGT) sensors 3 is between 20-735°C (68-1, 355°F).
8. The engine coolant temperature (ECT) sensor is greater than 70°C (158°F).
9. The fuel temperature is less than 150°C (302°F).
10. The BARO pressure is greater than 40 kPa (5.8 psi)
11. The APP sensor is less than 1 percent.
12. The diesel exhaust fluid temperature is greater than -7°C (+19°F).
13. The diesel exhaust fluid tank is not empty.
14. The brake pedal and accelerator pedal are in the released position.
15. The transmission is in Park or Neutral.

The scan tool DPF Regeneration Inhibit reason parameter will display a reason for not enabling or aborting the DPF service regeneration. Refer to the reasons that are displayed and the corrective action for each reason.

Service Regeneration Unsuccessful

Reference Information

Description and Operation

Exhaust Aftertreatment System Description

DTC Type Reference

Powertrain Diagnostic Trouble Code (DTC) Type Definitions

Scan Tool Reference

Control Module References for scan tool information

DPF Service Regeneration

Note. If you were not referred to this procedure from another diagnostic, DO NOT perform the Service Regeneration. Do not refuel the vehicle during DPF Service Regeneration. The scan tool must remain connected to the data communication link (DCL) during the entire service regeneration procedure. Do not perform the DPF Service Regeneration if the diesel exhaust fluid temperature (DEF) is less than -7°C (+19°F). Fuel level should be greater 15% to ensure a successful regeneration.

1. Ignition ON.
2. Verify there are no DTCs set, except DTC P2463. If another DTC is set Refer to «Diagnostic Trouble Code (DTC) List - Vehicle»(/gmc/sierra-2500/2012-2012/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures__diagnostic-trouble-code-dtc-list) . If another DTC is not set
3. Park the vehicle outside the repair facility and away from any obstacles.
4. With the vehicle in Park, use the throttle to increase the engine speed to 3000 RPM while looking for the speedometer to move slightly (greater than 1 mph). If this signal noise exists, inch the vehicle forward, place in park and repeat until there is no response seen from the speedometer. This will avoid a vehicle speed based interrupt of the service regeneration.
5. Place the transmission in Park and apply the parking brake.
6. Clear the DTCs with a scan tool before commanding a DPF Service Regeneration.
7. Observe the scan tool DPF Regenerations Completed parameter and record the value.
8. Open the hood.
9. Check the following fluid levels before and after this procedure: DEF Engine oil Engine coolant Power steering Transmission
10. Select the DPF Service Regeneration in the Output Controls menu and follow the instruction on the scan tool.
11. Command the DPF Service Regeneration ON with a scan tool. If the service regeneration failed to start Observe the DPF Reg Inhibit Reason parameter on the scan tool to identify the Reg Inhibit Reason and refer to the Service Regeneration Unsuccessful table in Diagnostic Aids. If the service regeneration starts
12. When the service regeneration is complete, the DPF Regeneration Status parameter will display Complete and the DPF Regenerations Completed parameter will increment by 1 from the value previously recorded. If the service regeneration did not complete, was aborted, or the Regeneration Completed did not increment Refer to the Service Regeneration Unsuccessful table in Diagnostic Aids above. If the Service Regeneration completed
13. Allow the engine to cool by idling for an additional 15 minutes. Command the Reductant Injector ON and OFF several times with a scan tool.
14. Clear the DTCs with a scan tool.
15. Ignition OFF for 90 s.

Perform the Diagnostic Repair Verification .

Exhaust Particulate Filter Replacement (43 Series) , Exhaust Particulate Filter Replacement (03 Series) , Exhaust Particulate Filter Replacement (53 Series) .

Diesel Particulate Filter (DPF) Regeneration Enable

Note. The DPF Regeneration Enable is required when specific service procedures have been performed. Do not perform a DPF Regeneration Enable unless instructed to in the Repair Instruction section of the service procedure. After the system is repair, perform the following to avoid possible damage to the DPF.

1. Ignition ON, clear the DTCs with a scan tool.
2. Select DPF Regeneration Enable with a scan tool.
3. Select ON. The DPF Regeneration Reason parameter should display DLC Override.
4. Exit the Special Function menu. Remove the scan tool.

Scheme 2

Engine Coolant Temperature Sensor Replacement

Scheme 3

Charge Air Temperature Sensor Replacement (Turbocharger)

Scheme 4

Charge Air Temperature Sensor Replacement (Charge Air Outlet Duct)

Scheme 5

Mass Airflow Sensor with Intake Air Temperature Sensor Replacement

Scheme 6

Throttle Body Assembly Replacement

Scheme 7

Intake Air Heater Replacement

Scheme 8

Manifold Absolute Pressure Sensor Replacement

Scheme 9

Nitrogen Oxide Sensor Replacement - Position 1

Scheme 10

Nitrogen Oxide Sensor Replacement - Position 2

Removal Procedure

1. Remove the connector position assurance (CPA) retainer.
2. Disconnect the accelerator pedal position (APP) sensor electrical connector (1).
3. Remove the accelerator pedal bolts.
4. Remove the accelerator pedal.

Installation Procedure

1. Position the accelerator pedal to the accelerator pedal bracket.
2. Install the accelerator pedal bolts and tighten to 9 N.m (80 lb in)..
3. Connect the APP sensor electrical connector (1).
4. Install the CPA retainer.
5. Connect a scan tool to the diagnostic port in order to test for proper throttle-opening and throttle-closing range.
6. Operate the accelerator pedal and monitor the throttle angles. The accelerator pedal should operate freely, without binding, between a closed throttle, and a wide open throttle (WOT).
7. Verify that the vehicle meets the following conditions: The vehicle is not in a reduced engine power mode. The ignition is ON. The engine is OFF.
8. Inspect the carpet fit under the accelerator pedal.

Metal Collar Quick Connect Fitting Service

Special Tools

1. J 43178 Fuel Line Disconnect Tool
2. J 44581 Fuel Line Disconnect Tool

1. Disconnect the negative battery cable. Refer to «Battery Negative Cable Disconnection and Connection (TP2)»(/gmc/sierra-2500/2012-2012/remont/charging-system/#battery-charging-system-and-starting-system) , «Battery Negative Cable Disconnection and Connection (Single Battery)»(/gmc/sierra-2500/2012-2012/remont/charging-system/#battery-charging-system-and-starting-system) .
2. Remove the fuel fill cap.
3. Remove the retainers from the fuel feed and return pipe quick connect fittings.
4. Using compressed air, blow any dirt or debris from around the fitting.
5. Using the correct end of J 44581 Fuel Line Disconnect Tool for the size of the fitting. Insert J 44581 Fuel Line Disconnect Tool into the female connector, then push inward in order to release the locking tabs.
6. If the vehicle is a cab/chassis, it may be necessary to use J 43178 Fuel Line Disconnect Tool in order to release the quick connect fittings at the sending unit.
7. Pull the connection apart.
8. Use a clean shop towel in order to wipe off the male end. CAUTION: If necessary, remove rust or burrs from the fuel pipes with an emery cloth. Use a radial motion with the fuel pipe end in order to prevent damage to the O-ring sealing surface. Use a clean shop towel in order to wipe off the male tube ends. Inspect all the connections for dirt and burrs. Clean or replace the components and assemblies as required.
9. Inspect both ends of the fitting for dirt and burrs. Clean or replace the components as required.

1. Apply a few drops of clean engine oil to the male connection end.
2. Push both sides of the fittings together in order to snap the retaining tabs into place.
3. Once installed, pull on both sides of the connections in order to make sure the connection is secure.
4. Install the retainers to the fuel feed/return pipes.
5. Install the fuel fill cap.
6. Connect the negative battery cable. Refer to «Battery Negative Cable Disconnection and Connection (TP2)»(/gmc/sierra-2500/2012-2012/remont/charging-system/#battery-charging-system-and-starting-system) , «Battery Negative Cable Disconnection and Connection (Single Battery)»(/gmc/sierra-2500/2012-2012/remont/charging-system/#battery-charging-system-and-starting-system) .

1. Relieve the fuel system pressure before servicing any fuel system connection. Refer to the «Fuel Pressure Relief (Without CH-48027)»(/gmc/sierra-2500/2012-2012/remont/testing-diagnostics/#engine-controlsfuel-48l-53l-60l-62l-repair-instructions__fuel-pressure-relief-without-ch-48027) , «Fuel Pressure Relief (CH-48027)»(/gmc/sierra-2500/2012-2012/remont/testing-diagnostics/#engine-controlsfuel-48l-53l-60l-62l-repair-instructions__fuel-pressure-relief-ch-48027) .
2. Using compressed air, blow any dirt out of the quick-connect fitting.
3. This step applies to Bartholomew style connectors ONLY. Squeeze the plastic quick-connect fitting release tabs.
4. This step applies to Q Release style connectors ONLY. Release the fitting by Pushing the tab toward the other side of the slot in the fitting.
5. This step applies to Squeeze to Release style connectors ONLY. Squeeze where indicated by arrows on both sides of the plastic ring surrounding the quick-connect fitting.
6. This step applies to Squeeze to Release style connectors ONLY. Push in the male side slightly in order to slide the retainer away from the retainers, squeeze where indicated by arrows on both sides of the plastic ring surrounding the quick-connect fitting.
7. This step applies to Sliding Retainer style connectors ONLY. Release the fitting by pressing on one side of the release tab causing it to push in slightly. If the tab doesn't move try pressing the tab in from the opposite side. The tab will only move in one direction.
8. This step applies to the Global Connector style only. Push the connector toward the tube in order to release the pressure. Press and hold down the release mechanism, and pull the connector straight out.
9. This step applies to the TI Loc style only. Push the connector toward the tube in order to release the pressure. Release the redundant latch (1) with two fingers or a flat bladed tool. Then press and hold down the bottom release mechanism (2) and pull the connector straight out.
10. This step applies to the Safe Lock style only. Push the connector toward the tube in order to release the pressure. Release the second latch (1) with two fingers. Then press and hold down the bottom release mechanism (2) and pull the connector straight out.
11. Using a clean shop towel, wipe off the male pipe end.
12. Inspect both ends of the fitting for dirt and burrs.
13. Clean or replace components as necessary.

1. Apply a few drops of clean engine oil to the male pipe end.
2. Push both sides of the quick-connect fitting together in order to cause the retaining feature to snap into place.
3. Pull on both sides of the quick-connect fitting to make sure the connection is secure.
4. Insert the tube in the connector until the retainer snaps in place.
5. Push down on the redundant latch (1) until it is fully engaged and snapped into position.
6. Insert the tube in the connector until the retainer snaps in place.
7. Push down on the second latch (1) in order to secure the connection.
8. Inspect for leaks using the following procedure: Turn the ignition ON, with the engine OFF for 2 seconds. Turn the ignition OFF, for 10 seconds. Turn the ignition ON, with the engine OFF for 2 seconds. Turn the ignition OFF. Inspect for leaks.

Fuel System Priming

Note. In order for the diesel fuel system to work properly, the fuel lines must be full of fuel and contain no air. If air gets into the fuel lines, it will be necessary to prime the fuel system to eliminate the air before operating the vehicle. Air could have entered the system in one of the following ways: The vehicle ran out of fuel. The filter was removed for service or replacement. The fuel lines were removed or disconnected for servicing. The fuel filter water drain cock was opened while the engine was running. If one or more of the above occurred, air has entered the fuel system and you will need to prime the system prior to operating the vehicle.

1. Prior to priming the fuel system, ensure that the following has been completed: There is fuel in the fuel tank. The fuel filter has been installed and properly tightened. The fuel lines are properly connected. The fuel filter is cool to the touch. Any dirt or debris has been removed from the fuel filter adapter and vent valve screw.
2. Remove the air cleaner outlet duct. Refer to «Air Cleaner Outlet Duct Replacement»(/gmc/sierra-2500/2012-2012/remont/testing-diagnostics/#engine-controlsfuel-66l-lgh-lml-repair-instructions) .
3. Open the vent valve screw (1) by turning the screw counterclockwise several full turns.
4. Operate the priming pump (1) by repeatedly pumping until a small amount of fuel seeps from the vent valve. Allow the pump to fully return upward between pumps. When fuel is present, the filter is full of fuel and the system is primed.
5. Close the vent valve screw.
6. Clean any fuel which accumulated on the fuel filter adapter.
7. Install the air cleaner outlet duct. Refer to «Air Cleaner Outlet Duct Replacement»(/gmc/sierra-2500/2012-2012/remont/testing-diagnostics/#engine-controlsfuel-66l-lgh-lml-repair-instructions) .
8. Start the engine and allow the engine to idle for a few minutes.
9. Check the fuel system for leaks.

1. Drain the fuel from the fuel filter. Refer to «Water-in-Fuel Draining»(/gmc/sierra-2500/2012-2012/remont/testing-diagnostics/#engine-controlsfuel-66l-lgh-lml-repair-instructions__water-in-fuel-draining) .
2. Remove the right side wheel house liner. Refer to «Front Wheelhouse Liner Replacement - Right Side (GMC)»(/gmc/sierra-2500/2012-2012/remont/frames-subframes-crossmembers/#frame-and-underbody) , «Front Wheelhouse Liner Replacement - Right Side (Chevrolet)»(/gmc/sierra-2500/2012-2012/remont/frames-subframes-crossmembers/#frame-and-underbody)
3. Disconnect the water-in-fuel sensor wiring pigtail (2) from the engine wiring harness electrical connector.
4. Remove the fuel filter from the fuel filter adapter.
5. Remove the water-in-fuel sensor from the fuel filter.

1. Install the water-in-fuel sensor to the NEW fuel filter, and tighten 1/2 turn after the seal contacts the filter.
2. Install the NEW fuel filter to the fuel filter adapter, and tighten 1/4 turn after the seal contacts the filter adapter.
3. Connect the water-in-fuel sensor wiring pigtail (2) to the engine wiring harness electrical connector.
4. Prime the fuel system. Refer to «Fuel System Priming»(/gmc/sierra-2500/2012-2012/remont/testing-diagnostics/#engine-controlsfuel-66l-lgh-lml-repair-instructions__fuel-system-priming) .
5. Start the engine. If the engine stalls, repeat the above step.
6. Once the engine starts, inspect for fuel leaks.
7. Install the right side wheel house liner. Refer to «Front Wheelhouse Liner Replacement - Right Side (GMC)»(/gmc/sierra-2500/2012-2012/remont/frames-subframes-crossmembers/#frame-and-underbody) , «Front Wheelhouse Liner Replacement - Right Side (Chevrolet)»(/gmc/sierra-2500/2012-2012/remont/frames-subframes-crossmembers/#frame-and-underbody)

Fuel Filter Life Reset

This message will appear when a reset is performed either by using the steering wheel controls or following manual procedure.

1. Reset the fuel filter monitor.
2. For vehicles with steering wheel controls, press and hold the select button for 5 seconds while the FUEL FILTER LIFE message is displayed. This message will appear on the driver information center (DIC) for ten seconds.
3. For vehicles without steering wheel controls, do the following: Without pressing the pedals, turn the ignition key to the ON position without starting the engine. Wait 5 seconds. Completely press the brake and the accelerator pedals simultaneously and hold for 10 seconds. The system is now reset. Turn the ignition key OFF.
4. The next time the engine is started, the message will no longer be displayed. ALWAYS reset the FUEL FILTER LIFE system after a fuel filter change.

Scheme 11

Fuel Filter Bracket Replacement

1. Remove the fuel filter. Refer to «Fuel Filter Replacement»(/gmc/sierra-2500/2012-2012/remont/testing-diagnostics/#engine-controlsfuel-66l-lgh-lml-repair-instructions) .
2. Disconnect the water in fuel sensor wiring pigtail (2) from the engine wiring harness electrical connector.
3. Remove the water in fuel sensor (1) from the fuel filter.

1. Install the water in fuel sensor (1) to the fuel filter, and tighten 1/2 turn after the seal contacts the filter.
2. Connect the water in fuel sensor wiring pigtail (2) to the engine wiring harness electrical connector.
3. Install the fuel filter. Refer to «Fuel Filter Replacement»(/gmc/sierra-2500/2012-2012/remont/testing-diagnostics/#engine-controlsfuel-66l-lgh-lml-repair-instructions) .
4. Prime the fuel system. Refer to «Fuel System Priming»(/gmc/sierra-2500/2012-2012/remont/testing-diagnostics/#engine-controlsfuel-66l-lgh-lml-repair-instructions__fuel-system-priming) .
5. Start the engine. If the engine stalls, repeat the above step.
6. Once the engine starts, inspect for fuel leaks.

Water-in-Fuel Draining

1. Attach a small piece of hose to the drain onto the water in fuel sensor.
2. Place the other end of the piece of hose into an approved fuel-resistant container.
3. Open the drain 3 or 4 turns or until the water contaminated fuel seeps from the drain.
4. Operate the priming pump (1) until only diesel fuel is visible. Allow the pump to fully return upward between pushes.
5. Tighten the drain.
6. Remove the container and hose.

1. Remove the air cleaner outlet duct. Refer to «Air Cleaner Outlet Duct Replacement»(/gmc/sierra-2500/2012-2012/remont/testing-diagnostics/#engine-controlsfuel-66l-lgh-lml-repair-instructions)
2. Remove the upper intake manifold brace bolt (2).
3. Remove the fuel filter bracket bolts (3).
4. Remove the upper intake manifold brace (1).
5. Remove the fuel filter hoses (2) and (3).
6. Remove the fuel filter bracket bolts (4).
7. Remove the fuel filter and bracket (1).

1. Install the fuel filter bracket bolts (4) and tighten to 20 N.m(15 lb ft).
2. Install the fuel filter hoses (2) and (3).
3. Install the upper intake manifold brace (1)..
4. Install the upper intake manifold brace bolt (2) and tighten to 25 N.m(18 lb ft).
5. Install the fuel filter bracket bolts (3) and tighten to 20 N.m(15 lb ft).
6. Install the air cleaner outlet duct. Refer to «Air Cleaner Outlet Duct Replacement»(/gmc/sierra-2500/2012-2012/remont/testing-diagnostics/#engine-controlsfuel-66l-lgh-lml-repair-instructions)

Fuel Tank Draining (Gasoline)

Special Tools

CH 45004 Fuel Tank Siphon Hose

1. Disconnect the negative battery cable. Refer to «Battery Negative Cable Disconnection and Connection (TP2)»(/gmc/sierra-2500/2012-2012/remont/charging-system/#battery-charging-system-and-starting-system) , «Battery Negative Cable Disconnection and Connection (Single Battery)»(/gmc/sierra-2500/2012-2012/remont/charging-system/#battery-charging-system-and-starting-system) .
2. Remove the fuel fill cap.
3. Raise and suitably support the vehicle. Refer to «Lifting and Jacking the Vehicle»(/gmc/sierra-2500/2012-2012/remont/ignition-switchsteering-lock/#general-information__lifting-and-jacking-the-vehicle) .
4. Insert the CH 45004 hose into the tank.
5. Attach the CH 45004 hose to a hand or air operated pump device.
6. Using a hand or air operated pump drain as much fuel from the tank as possible.

Fuel Tank Draining (Emission Reduction Fluid)

1. Ensure the ignition is OFF.
2. Raise and support the vehicle. Refer to «Lifting and Jacking the Vehicle»(/gmc/sierra-2500/2012-2012/remont/ignition-switchsteering-lock/#general-information__lifting-and-jacking-the-vehicle) .
3. Using only a Low pressure clean water hose, spray the upper surfaces of the Diesel Exhaust Fluid (DEF) Tank and pump supply module, the injection hose, and the fill hose assembly, to remove all dirt and debris.
4. Using only a Low pressure air wand or air gun, direct air along the same surfaces to both dry and remove any further contaminants.
5. Using a clean white shop towel, carefully dry connections and joints by hand to ensure dryness and cleanliness.
6. Collapse the spring clamp (1) and disconnect the filler hose.
7. Insert the hose from the pump devise into the DEF tank.
8. Using a hand or air operated pump device, drain as much DEF from the tank as possible into an approved container and dispose of properly.
9. Align the DEF fill hose to the DEF tank and install the hose into position. Secure the spring clamp (1) into position on the hose.

1. Disconnect the filler tube from the tank. Refer to «Fuel Tank Filler Hose Replacement (Pickup)»(/gmc/sierra-2500/2012-2012/remont/testing-diagnostics/#engine-controlsfuel-66l-lgh-lml-repair-instructions) .
2. Disconnect the fuel feed and return pipes (1). Refer to «Plastic Collar Quick Connect Fitting Service»(/gmc/sierra-2500/2012-2012/remont/testing-diagnostics/#engine-controlsfuel-66l-lgh-lml-repair-instructions) .
3. Remove the fuel tank shield. Refer to «Fuel Tank Shield Replacement»(/gmc/sierra-2500/2012-2012/remont/frames-subframes-crossmembers/#frame-and-underbody) .
4. Support the fuel tank with a suitable jack.
5. Remove the fuel tank strap bolts (1).
6. Disconnect the fuel sender electrical connector.
7. Remove the fuel tank (1).
8. If replacing the tank, remove the fuel sender. Refer to «Fuel Tank Fuel Pump Module Replacement»(/gmc/sierra-2500/2012-2012/remont/testing-diagnostics/#engine-controlsfuel-66l-lgh-lml-repair-instructions__fuel-tank-fuel-pump-module-replacement) .
9. Transfer parts as necessary.

1. Install the fuel tank (1).
2. Support the fuel tank with a suitable jack.
3. Connect the fuel sender electrical connector. CAUTION: Refer to «Fastener Caution»(/gmc/sierra-2500/2012-2012/remont/oem-general-information/#dangers-warnings-and-cautions__fastener-caution) .
4. Install the fuel tank strap bolts (1) and tighten to 40 N.m (30 lb ft).
5. Connect the filler tube to the tank. Refer to «Fuel Tank Filler Hose Replacement (Pickup)»(/gmc/sierra-2500/2012-2012/remont/testing-diagnostics/#engine-controlsfuel-66l-lgh-lml-repair-instructions) .
6. Install the fuel tank shield. Refer to «Fuel Tank Shield Replacement»(/gmc/sierra-2500/2012-2012/remont/frames-subframes-crossmembers/#frame-and-underbody) .

1. Raise and suitably support the vehicle. Refer to «Lifting and Jacking the Vehicle»(/gmc/sierra-2500/2012-2012/remont/ignition-switchsteering-lock/#general-information__lifting-and-jacking-the-vehicle) .
2. Disconnect the fuel and evaporative emission lines (1). If equipped, disconnect the rear connections. Refer to «Plastic Collar Quick Connect Fitting Service»(/gmc/sierra-2500/2012-2012/remont/testing-diagnostics/#engine-controlsfuel-66l-lgh-lml-repair-instructions) .
3. Loosen the fuel fill hose clamp (1) at the fuel tank.
4. Remove the fuel fill pipe and vent hose from the tank.
5. Drain the fuel tank. Refer to «Fuel Tank Draining (Gasoline)»(/gmc/sierra-2500/2012-2012/remont/testing-diagnostics/#engine-controlsfuel-66l-lgh-lml-repair-instructions__fuel-tank-draining-gasoline) , «Fuel Tank Draining (Emission Reduction Fluid)»(/gmc/sierra-2500/2012-2012/remont/testing-diagnostics/#engine-controlsfuel-66l-lgh-lml-repair-instructions__fuel-tank-draining-emission-reduction-fluid) .
6. Disconnect the sending unit electrical connectors (1).
7. If necessary, remove the fuel tank shield bolts.
8. Remove the fuel tank shield from the fuel tank shield tabs.
9. Place a suitable adjustable jack under the fuel tank.
10. Remove the fuel tank strap bolts.
11. Remove the fuel tank straps.
12. Lower the fuel tank.
13. With the aid of an assistant, place the fuel tank in a suitable work area.
14. Cap the fuel lines on the vehicle in order to prevent possible fuel system contamination.
15. If replacing the fuel tank, remove the sending unit. Refer to «Fuel Tank Fuel Pump Module Replacement»(/gmc/sierra-2500/2012-2012/remont/testing-diagnostics/#engine-controlsfuel-66l-lgh-lml-repair-instructions__fuel-tank-fuel-pump-module-replacement) .

1. If the fuel tank was replaced, install the sending unit. Refer to «Fuel Tank Fuel Pump Module Replacement»(/gmc/sierra-2500/2012-2012/remont/testing-diagnostics/#engine-controlsfuel-66l-lgh-lml-repair-instructions__fuel-tank-fuel-pump-module-replacement) .
2. Remove the caps from the fuel lines.
3. With the aid of an assistant, place the fuel tank on the jack.
4. Raise the fuel tank.
5. Install the fuel tank straps. CAUTION: Refer to «Fastener Caution»(/gmc/sierra-2500/2012-2012/remont/oem-general-information/#dangers-warnings-and-cautions__fastener-caution) .
6. Install the fuel tank strap bolts and tighten to 40 N.m (30 lb ft).
7. Remove the jack from under the fuel tank.
8. Install the fuel tank shield into the fuel tank shield tabs.
9. Install the fuel tank shield bolts and tighten to 18 N.m (13 lb ft).
10. Connect the sending unit electrical connectors (1).
11. Install the fuel fill pipe clamp (1) and tighten to 4 N.m (35 lb in).
12. Connect the fuel feed and evaporative emission lines (1). Refer to «Plastic Collar Quick Connect Fitting Service»(/gmc/sierra-2500/2012-2012/remont/testing-diagnostics/#engine-controlsfuel-66l-lgh-lml-repair-instructions) .
13. Fill the fuel tank.
14. Install the fuel fill cap.
15. Connect the negative battery cable. Refer to «Battery Negative Cable Disconnection and Connection (TP2)»(/gmc/sierra-2500/2012-2012/remont/charging-system/#battery-charging-system-and-starting-system) , «Battery Negative Cable Disconnection and Connection (Single Battery)»(/gmc/sierra-2500/2012-2012/remont/charging-system/#battery-charging-system-and-starting-system) .
16. Prime the fuel system. Refer to «Fuel System Priming»(/gmc/sierra-2500/2012-2012/remont/testing-diagnostics/#engine-controlsfuel-66l-lgh-lml-repair-instructions__fuel-system-priming) .
17. Start the engine. If the engine stalls, repeat the above step.
18. Once the engine starts, inspect for fuel leaks.

1. Loosen the fuel fill and vent hose clamps (1, 2) at the tank.
2. Remove the fuel fill and vent hose from the tank.
3. Drain the fuel tank. Refer to «Fuel Tank Draining (Gasoline)»(/gmc/sierra-2500/2012-2012/remont/testing-diagnostics/#engine-controlsfuel-66l-lgh-lml-repair-instructions__fuel-tank-draining-gasoline) , «Fuel Tank Draining (Emission Reduction Fluid)»(/gmc/sierra-2500/2012-2012/remont/testing-diagnostics/#engine-controlsfuel-66l-lgh-lml-repair-instructions__fuel-tank-draining-emission-reduction-fluid) .
4. Disconnect the sending unit electrical connector.
5. Disconnect the fuel feed and return lines (1) from the sending unit. Refer to «Plastic Collar Quick Connect Fitting Service»(/gmc/sierra-2500/2012-2012/remont/testing-diagnostics/#engine-controlsfuel-66l-lgh-lml-repair-instructions) .
6. Raise and suitably support the vehicle. Refer to «Lifting and Jacking the Vehicle»(/gmc/sierra-2500/2012-2012/remont/ignition-switchsteering-lock/#general-information__lifting-and-jacking-the-vehicle) .
7. Remove the fuel tank shield bolts.
8. Remove the fuel tank shield.
9. Remove the fuel tank strap bolts.
10. Remove the fuel tank straps.
11. Lower the fuel tank.
12. With the aid of an assistant, place the fuel tank in a suitable work area.
13. Cap the fuel lines in order to prevent possible fuel system contamination.
14. If replacing the fuel tank, remove the sending unit. Refer to «Fuel Tank Fuel Pump Module Replacement»(/gmc/sierra-2500/2012-2012/remont/testing-diagnostics/#engine-controlsfuel-66l-lgh-lml-repair-instructions__fuel-tank-fuel-pump-module-replacement) .

1. If the fuel tank was replaced, install the sending unit. Refer to «Fuel Tank Fuel Pump Module Replacement»(/gmc/sierra-2500/2012-2012/remont/testing-diagnostics/#engine-controlsfuel-66l-lgh-lml-repair-instructions__fuel-tank-fuel-pump-module-replacement) .
2. Remove the caps from the fuel lines.
3. With the aid of an assistant, place the fuel tank on the jack.
4. Raise the fuel tank.
5. Install the fuel tank straps. CAUTION: Refer to «Fastener Caution»(/gmc/sierra-2500/2012-2012/remont/oem-general-information/#dangers-warnings-and-cautions__fastener-caution) .
6. Install the fuel tank strap bolts and tighten to 40 N.m (30 lb ft).
7. Remove the jack from under the fuel tank.
8. If equipped, install the fuel tank cover.
9. If equipped, install the fuel tank cover bolts and tighten to 18 N.m (13 lb ft).
10. Lower the vehicle.
11. Connect the fuel feed and return lines (1) to the sending unit. Refer to «Plastic Collar Quick Connect Fitting Service»(/gmc/sierra-2500/2012-2012/remont/testing-diagnostics/#engine-controlsfuel-66l-lgh-lml-repair-instructions) .
12. Connect the sending unit electrical connector.
13. Install the fuel fill and vent hose to the tank.
14. Tighten the fuel fill and vent hose clamps (1, 2) at the tank to 4 N.m (35 lb in).
15. Fill the fuel tank.
16. Install the fuel fill cap.
17. Install the negative battery cable. Refer to «Battery Negative Cable Disconnection and Connection (TP2)»(/gmc/sierra-2500/2012-2012/remont/charging-system/#battery-charging-system-and-starting-system) , «Battery Negative Cable Disconnection and Connection (Single Battery)»(/gmc/sierra-2500/2012-2012/remont/charging-system/#battery-charging-system-and-starting-system) .
18. Using a scan tool, command the fuel transfer pump on.
19. Prime the fuel system. Refer to «Fuel System Priming»(/gmc/sierra-2500/2012-2012/remont/testing-diagnostics/#engine-controlsfuel-66l-lgh-lml-repair-instructions__fuel-system-priming) .
20. Start the engine. If the engine stalls, repeat the above step.
21. Once the engine starts, inspect for fuel leaks.

Scheme 12

Fuel Level Sensor Replacement

1. Loosen the fuel fill cap to relieve the fuel system pressure.
2. Disconnect the balance pump electrical connector.
3. Raise and suitably support the vehicle. Refer to «Lifting and Jacking the Vehicle»(/gmc/sierra-2500/2012-2012/remont/ignition-switchsteering-lock/#general-information__lifting-and-jacking-the-vehicle) .
4. Clean the fuel line connections and surrounding areas at the pump before disconnecting to avoid possible fuel system contamination.
5. Disconnect the fuel lines from the pump.
6. Slide the pump out of the bracket.
7. Cap the fuel lines.

1. Remove the caps from the fuel lines.
2. Install the NEW fuel line O-rings.
3. Position the new balance pump into the bracket.
4. Connect the fuel lines to the balance pump. Use a backup wrench to prevent the pump from turning. Tighten the fittings to 30 N.m (22 lb ft).
5. Lower the vehicle.
6. Connect the balance pump electrical connector.
7. Tighten the fuel fill cap.
8. Using a scan tool, command the fuel transfer pump on.
9. Prime the fuel system. Refer to «Fuel System Priming»(/gmc/sierra-2500/2012-2012/remont/testing-diagnostics/#engine-controlsfuel-66l-lgh-lml-repair-instructions__fuel-system-priming) .
10. Start the engine. If the engine stalls, repeat the above step.
11. Once the engine starts, inspect for fuel leaks.

Fuel Tank Fuel Pump Module Replacement

Special Tools

CH-45722 Fuel Tank Sender Wrench

For equivalent regional tools, refer to Special Tools (Diagnostic Tools Diesel) .

1. Remove the fuel tank. Refer to «Fuel Tank Replacement (Pickup)»(/gmc/sierra-2500/2012-2012/remont/testing-diagnostics/#engine-controlsfuel-66l-lgh-lml-repair-instructions) , «Fuel Tank Replacement (Cab/Chassis - Front)»(/gmc/sierra-2500/2012-2012/remont/testing-diagnostics/#engine-controlsfuel-66l-lgh-lml-repair-instructions) , «Fuel Tank Replacement (Cab/Chassis - Rear)»(/gmc/sierra-2500/2012-2012/remont/testing-diagnostics/#engine-controlsfuel-66l-lgh-lml-repair-instructions) .
2. Disconnect the fuel feed and return pipes (1). Refer to «Plastic Collar Quick Connect Fitting Service»(/gmc/sierra-2500/2012-2012/remont/testing-diagnostics/#engine-controlsfuel-66l-lgh-lml-repair-instructions) .
3. Using the CH-45722 wrench, remove the cam lock ring (1) by turning counter-clockwise.
4. Remove the fuel sender assembly (1) and O-ring (2).

1. Install the fuel sender assembly (1) and O-ring (2).
2. Using the CH-45722 wrench, install the cam lock ring (1) by turning clockwise.
3. Connect the fuel feed and return pipes (1). Refer to «Plastic Collar Quick Connect Fitting Service»(/gmc/sierra-2500/2012-2012/remont/testing-diagnostics/#engine-controlsfuel-66l-lgh-lml-repair-instructions) .
4. Install the fuel tank. Refer to «Fuel Tank Replacement (Pickup)»(/gmc/sierra-2500/2012-2012/remont/testing-diagnostics/#engine-controlsfuel-66l-lgh-lml-repair-instructions) , «Fuel Tank Replacement (Cab/Chassis - Front)»(/gmc/sierra-2500/2012-2012/remont/testing-diagnostics/#engine-controlsfuel-66l-lgh-lml-repair-instructions) , «Fuel Tank Replacement (Cab/Chassis - Rear)»(/gmc/sierra-2500/2012-2012/remont/testing-diagnostics/#engine-controlsfuel-66l-lgh-lml-repair-instructions) .

1. Reposition the fuel filter hose clamp(s) (1 or 2) at the fuel filter adapter.
2. Reposition the fuel filter hose clamp(s) (1 or 2) at the fuel injection fuel feed manifold and/or the fuel feed pipe.
3. Remove the fuel hose retainer (3) from the appropriate fuel filter hose.
4. Remove the fuel filter hose (1) from the fuel filter adapter and the fuel injection fuel feed manifold, if required.
5. Remove the fuel filter hose (2) from the fuel filter adapter and the fuel feed pipe, if required.

1. Install the fuel filter hose (1) to the fuel filter adapter and the fuel injection fuel feed manifold, if required.
2. Install the fuel filter hose (2) from the fuel filter adapter and the fuel feed pipe, if required.
3. Install the fuel hose retainer (3) to the fuel filter hose(s).
4. Position the fuel filter hose clamp(s) (1 or 2) at the fuel injection fuel feed manifold and/or the fuel feed pipe.
5. Position the fuel filter hose clamp(s) (1 or 2) at the fuel filter adapter.
6. Prime the fuel system. Refer to «Fuel System Priming»(/gmc/sierra-2500/2012-2012/remont/testing-diagnostics/#engine-controlsfuel-66l-lgh-lml-repair-instructions__fuel-system-priming) .
7. Start the engine. If the engine stalls, repeat the above step.
8. Once the engine starts, inspect for fuel leaks.

Scheme 13

Fuel Return Hose Replacement - Fuel Return Pipe to Fuel Injection Pump

Fuel Hose Replacement - Fuel Injection Pump to Fuel Feed Block

Fuel Hose Replacement - Fuel Injection Pump to Fuel Feed Block

1. Disconnect the fuel feed and return lines. Refer to «Metal Collar Quick Connect Fitting Service»(/gmc/sierra-2500/2012-2012/remont/testing-diagnostics/#engine-controlsfuel-66l-lgh-lml-repair-instructions__metal-collar-quick-connect-fitting-service) .
2. Remove the fuel line bracket nut.
3. Remove the fuel line bracket from the stud.
4. Raise and suitably support the vehicle. Refer to «Lifting and Jacking the Vehicle»(/gmc/sierra-2500/2012-2012/remont/ignition-switchsteering-lock/#general-information__lifting-and-jacking-the-vehicle) .
5. Remove the fuel bundle clip (2) from the transmission brackets (1).
6. Disconnect the chassis harness from the retaining clips.
7. Disconnect the fuel feed and return lines from the fuel tank lines. Refer to «Plastic Collar Quick Connect Fitting Service»(/gmc/sierra-2500/2012-2012/remont/testing-diagnostics/#engine-controlsfuel-66l-lgh-lml-repair-instructions) .
8. Remove the fuel bundle nuts from the chassis.
9. Loosen the electronic brake control module (EBCM) bracket bolts (4).
10. Allow the EBCM to remain loose in order to allow fuel pipe clearance.
11. Remove the fuel bundle using the following procedure: Guide the fuel bundle pipes towards the rear of vehicle to clear the engine. Lower the fuel bundle while moving it forward and out.

1. Install the fuel pipe bundle using the following procedure: Install the fuel bundle to the chassis by guiding the pipes towards the rear of vehicle. Lift the fuel pipes, while guiding the forward portion of the pipes up towards the engine connections.
2. Install the fuel bundle nuts to the chassis and tighten to 16 N.m (12 lb ft).
3. Connect the fuel feed and return lines to the fuel tank lines. Refer to «Plastic Collar Quick Connect Fitting Service»(/gmc/sierra-2500/2012-2012/remont/testing-diagnostics/#engine-controlsfuel-66l-lgh-lml-repair-instructions) .
4. Connect the fuel bundle clip (2) to the transmission brackets (1).
5. Tighten the EBCM bracket bolts (4) to 25 N.m (18 lb ft).
6. Lower the vehicle.
7. Install the fuel line bracket to the stud.
8. Install the fuel line bracket nut and tighten to 16 N.m (12 lb ft).
9. Connect the fuel feed and return lines. Refer to «Metal Collar Quick Connect Fitting Service»(/gmc/sierra-2500/2012-2012/remont/testing-diagnostics/#engine-controlsfuel-66l-lgh-lml-repair-instructions__metal-collar-quick-connect-fitting-service) .
10. Prime the fuel system. Refer to «Fuel System Priming»(/gmc/sierra-2500/2012-2012/remont/testing-diagnostics/#engine-controlsfuel-66l-lgh-lml-repair-instructions__fuel-system-priming) .
11. Start the engine. If the engine stalls, repeat the above step.
12. Once the engine starts, inspect for fuel leaks.

1. Remove the front and auxiliary fuel tanks. Refer to «Fuel Tank Replacement (Cab/Chassis - Front)»(/gmc/sierra-2500/2012-2012/remont/testing-diagnostics/#engine-controlsfuel-66l-lgh-lml-repair-instructions) , «Fuel Tank Replacement (Cab/Chassis - Rear)»(/gmc/sierra-2500/2012-2012/remont/testing-diagnostics/#engine-controlsfuel-66l-lgh-lml-repair-instructions) .
2. Disconnect the pressure balance pump electrical connector.
3. Remove the fuel bundle nuts.
4. Remove the fuel bundle.

1. Install the fuel bundle.
2. Install the fuel bundle nuts and tighten to 16 N.m (12 lb ft).
3. Connect the pressure balance pump electrical connector.
4. Install the front and auxiliary fuel tanks. Refer to «Fuel Tank Replacement (Cab/Chassis - Front)»(/gmc/sierra-2500/2012-2012/remont/testing-diagnostics/#engine-controlsfuel-66l-lgh-lml-repair-instructions) , «Fuel Tank Replacement (Cab/Chassis - Rear)»(/gmc/sierra-2500/2012-2012/remont/testing-diagnostics/#engine-controlsfuel-66l-lgh-lml-repair-instructions) .

1. Disconnect the fuel feed and return lines. Refer to «Metal Collar Quick Connect Fitting Service»(/gmc/sierra-2500/2012-2012/remont/testing-diagnostics/#engine-controlsfuel-66l-lgh-lml-repair-instructions__metal-collar-quick-connect-fitting-service) .
2. Remove the fuel line bracket nut.
3. Remove the fuel line bracket from the stud.
4. Raise and suitably support the vehicle. Refer to «Lifting and Jacking the Vehicle»(/gmc/sierra-2500/2012-2012/remont/ignition-switchsteering-lock/#general-information__lifting-and-jacking-the-vehicle) .
5. Remove the fuel bundle clip (2) from the transmission brackets (1).
6. Disconnect the chassis harness from the retaining clips.
7. Disconnect the fuel feed and return lines from the fuel tank lines. Refer to «Plastic Collar Quick Connect Fitting Service»(/gmc/sierra-2500/2012-2012/remont/testing-diagnostics/#engine-controlsfuel-66l-lgh-lml-repair-instructions) .
8. Remove the fuel bundle nuts from the chassis.
9. Loosen the electronic brake control module (EBCM) bracket bolts (4).
10. Allow the EBCM to remain loose in order to allow fuel pipe clearance.
11. Remove the fuel bundle using the following procedure: Guide the fuel bundle pipes towards the rear of the vehicle to clear the engine. Lower the fuel bundle while moving it forward and out.

1. Install the fuel pipe bundle using the following procedure: Install the fuel bundle to the chassis by guiding the pipes towards the rear of vehicle. Lift the fuel pipes, while guiding the forward portion of the pipes up towards the engine connections.
2. Install the fuel bundle nuts to the chassis and tighten to 16 N.m (12 lb ft).
3. Connect the fuel feed and return lines to the fuel tank lines. Refer to «Plastic Collar Quick Connect Fitting Service»(/gmc/sierra-2500/2012-2012/remont/testing-diagnostics/#engine-controlsfuel-66l-lgh-lml-repair-instructions) .
4. Connect the fuel bundle clip (2) to the transmission brackets (1).
5. Tighten the EBCM bracket bolts (4) to 25 N.m (18 lb ft).
6. Lower the vehicle.
7. Install the fuel line bracket to the stud.
8. Install the fuel line bracket nut and tighten to 16 N.m (12 lb ft).
9. Connect the fuel feed and return lines. Refer to «Metal Collar Quick Connect Fitting Service»(/gmc/sierra-2500/2012-2012/remont/testing-diagnostics/#engine-controlsfuel-66l-lgh-lml-repair-instructions__metal-collar-quick-connect-fitting-service) .
10. Prime the fuel system. Refer to «Fuel System Priming»(/gmc/sierra-2500/2012-2012/remont/testing-diagnostics/#engine-controlsfuel-66l-lgh-lml-repair-instructions__fuel-system-priming) .
11. Start the engine. If the engine stalls, repeat the above step.
12. Once the engine starts, inspect for fuel leaks.

Scheme 14

Fuel Feed Pipe Replacement (Pump to Indirect Fuel Injector)

Scheme 15

Fuel Feed and Return Pipe Replacement

1. Remove the intake manifold cover. Refer to «Intake Manifold Cover Replacement»(/gmc/sierra-2500/2012-2012/remont/mechanical/#engine-mechanical-66l-lgh-lml-repair-instructions-on-vehicle) .
2. Remove the charge air inlet pipe. Refer to «Charge Air Cooler Inlet Pipe Replacement»(/gmc/sierra-2500/2012-2012/remont/testing-diagnostics/#engine-controlsfuel-66l-lgh-lml-repair-instructions) .
3. Remove the air cleaner outlet duct. Refer to «Air Cleaner Outlet Duct Replacement»(/gmc/sierra-2500/2012-2012/remont/testing-diagnostics/#engine-controlsfuel-66l-lgh-lml-repair-instructions) .
4. Remove the generator. Refer to «Generator Replacement (Diesel)»(/gmc/sierra-2500/2012-2012/remont/charging-system/#battery-charging-system-and-starting-system) .
5. Remove the A/C compressor bolts and reposition the A/C compressor.
6. Disengage the fuel return line by pulling upward on the cylindrical locking sleeve (1).
7. Remove the fuel return line (2) from the fuel injector (3).
8. Repeat steps 6-7 for the remaining injectors.
9. Remove the fuel return pipe bracket bolt from left valve cover.
10. Disconnect the fuel return hose vacuum line.
11. Remove the fuel return hose clip from back of A/C compressor bracket.
12. Disconnect the fuel return hose from the fuel feed pipe.
13. Remove the return hose from fuel return clip.
14. Remove the fuel return hose vacuum valve from bracket.
15. Remove the fuel injector fuel return line assembly (1).

1. Install the fuel injector fuel return line assembly (1).
2. Inspect the O-rings (1) for damage. Replace if necessary.
3. Inspect the fuel return line locking tabs (2) for damage. Replace the fuel return line assembly if necessary.
4. With the cylindrical locking sleeve (3) released in the upward position, install the fuel return line to the fuel injector.
5. Press down on the locking sleeve (3) to secure the connection.
6. Repeat steps 2-5 for the remaining injectors.
7. Install the fuel return hose vacuum valve to bracket.
8. Install the return hose to fuel return hose clip.
9. Connect the fuel return hose to fuel feed pipe.
10. Install the fuel return hose clip to back of A/C compressor bracket.
11. Connect the fuel return hose vacuum line.
12. Install the fuel return pipe bracket bolt to left valve cover.
13. Install the A/C compressor and bolts.
14. Install the generator. Refer to «Generator Replacement (Diesel)»(/gmc/sierra-2500/2012-2012/remont/charging-system/#battery-charging-system-and-starting-system) .
15. Install the air cleaner outlet duct. Refer to «Air Cleaner Outlet Duct Replacement»(/gmc/sierra-2500/2012-2012/remont/testing-diagnostics/#engine-controlsfuel-66l-lgh-lml-repair-instructions) .
16. Install the charge air inlet pipe. Refer to «Charge Air Cooler Inlet Pipe Replacement»(/gmc/sierra-2500/2012-2012/remont/testing-diagnostics/#engine-controlsfuel-66l-lgh-lml-repair-instructions) .
17. Install the intake manifold cover. Refer to «Intake Manifold Cover Replacement»(/gmc/sierra-2500/2012-2012/remont/mechanical/#engine-mechanical-66l-lgh-lml-repair-instructions-on-vehicle) .

1. Remove the rear exhaust gas recirculation cooler. Refer to «Exhaust Gas Recirculation Valve Cooler Replacement»(/gmc/sierra-2500/2012-2012/remont/cooling-system-mechanical/#engine-cooling-system) .
2. Prior to removing the fuel injector pipes, use compressed air to blow any debris from between the injector line and fittings. Wipe the fittings clean of debris.
3. Spray lithium grease, GM P/N 12346293 or equivalent, between the fuel injector line and fittings to assist in containing any debris during removal.
4. Remove the fuel pipe bracket fasteners (1) and fuel injector pipes (2).

1. Install the fuel injector pipes (2). Tighten the fittings to 41 N.m (30 lb ft).
2. After installing the fuel injector pipes, clean the injector pipes and apply sealant GM P/N 97720043, at the fittings to prevent moisture and debris from collecting between the line and fitting.
3. Install the fuel pipe bracket fasteners (1) and tighten to 10 N.m (89 lb in).
4. Install the rear exhaust gas recirculation cooler. Refer to «Exhaust Gas Recirculation Valve Cooler Replacement»(/gmc/sierra-2500/2012-2012/remont/cooling-system-mechanical/#engine-cooling-system) .
5. Start the engine. If the engine stalls, repeat the above step.
6. Inspect the fuel system for fuel leaks.

1. Remove the front exhaust gas recirculation cooler. Refer to «Exhaust Gas Recirculation Valve Cooler Replacement»(/gmc/sierra-2500/2012-2012/remont/cooling-system-mechanical/#engine-cooling-system) .
2. Reposition the charge air cooler pipe from the turbo.
3. Remove the fuel rail pressure sensor bracket shield.
4. Prior to removing the fuel injector pipes, use compressed air to blow any debris from between the injector line and fittings. Wipe the fittings clean of debris.
5. Spray lithium grease, GM P/N 12346293 or equivalent, between the fuel injector line and fittings to assist in containing any debris during removal.
6. Remove the fuel pipe bracket fasteners (1) and pipes (2).

1. Install the fuel injector pipes (2). Tighten the fittings to 4` N.m (30 lb ft).
2. Install the fuel pipe bracket fasteners (1) and tighten to 10 N.m (89 lb in).
3. After installing the fuel injector pipes, clean the injector pipes and apply sealant GM P/N 97720043, at the fittings to prevent moisture and debris from collecting between the line and fitting.
4. Install the fuel rail pressure sensor bracket shield.
5. Reposition the charge air cooler pipe to the turbo.
6. Install the front exhaust gas recirculation cooler. Refer to «Exhaust Gas Recirculation Valve Cooler Replacement»(/gmc/sierra-2500/2012-2012/remont/cooling-system-mechanical/#engine-cooling-system) .
7. Start the engine. If the engine stalls, repeat the above step.
8. Inspect the fuel system for fuel leaks.

1. Remove the high pressure fuel pipe fastener (1).
2. Remove the turbo charger assembly. Refer to «Turbocharger Replacement (LGH)»(/gmc/sierra-2500/2012-2012/remont/mechanical/#engine-mechanical-66l-lgh-lml-repair-instructions-on-vehicle) , «Turbocharger Replacement (LML)»(/gmc/sierra-2500/2012-2012/remont/mechanical/#engine-mechanical-66l-lgh-lml-repair-instructions-on-vehicle) .
3. Remove the high pressure fuel pipe fasteners (1).
4. Remove the high pressure fuel pipe fitting (2).
5. Remove the high pressure fuel pipe (3).

1. Install the high pressure fuel pipe fitting (2) and tighten to 30 N.m (22 lb ft).
2. Install the high pressure fuel pipe fasteners (1) and tighten to 10 N.m (89 lb in)
3. Install the high pressure fuel fastener (1) and tighten to 10 N.m (89 lb in)
4. Install the turbo charger assembly. Refer to «Turbocharger Replacement (LGH)»(/gmc/sierra-2500/2012-2012/remont/mechanical/#engine-mechanical-66l-lgh-lml-repair-instructions-on-vehicle) , «Turbocharger Replacement (LML)»(/gmc/sierra-2500/2012-2012/remont/mechanical/#engine-mechanical-66l-lgh-lml-repair-instructions-on-vehicle) .
5. Start the engine. If the engine does not start, repeat the above step.
6. Inspect the fuel system for leaks.

1. Remove the high pressure fuel pipe fastener (1).
2. Remove the center intake manifold. Refer to «Center Intake Manifold Replacement»(/gmc/sierra-2500/2012-2012/remont/mechanical/#engine-mechanical-66l-lgh-lml-repair-instructions-on-vehicle) .
3. Remove the high pressure fuel pipe fitting (1) at the fuel pump.
4. Remove the high pressure fuel pipe fitting (2) at the fuel rail.
5. Remove the high pressure fuel pipes (3) as an assembly.

1. Install the high pressure fuel pipe fitting (1) at the fuel pump and tighten to 38 N.m (28 lb ft).
2. Remove the high pressure fuel pipe fitting (2) at the fuel rail and tighten to 30 N.m (22 lb ft).
3. Install the high pressure fuel fastener (1) and tighten to 10 N.m (89 lb in)
4. Install the center intake manifold. Refer to «Center Intake Manifold Replacement»(/gmc/sierra-2500/2012-2012/remont/mechanical/#engine-mechanical-66l-lgh-lml-repair-instructions-on-vehicle) .
5. Start the engine. If the engine does not start, repeat the above step.
6. Inspect the fuel system for leaks.

1. Drain the fuel below the fuel fill neck. Refer to «Fuel Tank Draining (Emission Reduction Fluid)»(/gmc/sierra-2500/2012-2012/remont/testing-diagnostics/#engine-controlsfuel-66l-lgh-lml-repair-instructions__fuel-tank-draining-emission-reduction-fluid) .
2. Remove the filler housing fasteners (1).
3. Remove the filler hose ground fastener (1).
4. Loosen the hose clamps (2).
5. Remove the fuel tank filler hose (3).

1. Install the fuel tank filler hose (3).
2. Tighten the hose clamps (2) to 6 N.m (53 lb in).
3. Tighten the filler hose ground fastener (1) to 10 N.m (89 lb in).
4. Tighten the filler housing fasteners (1) to 10 N.m (89 lb in)
5. Fill the fuel to the previous level.

1. Drain the fuel below the fuel fill neck. Refer to «Fuel Tank Draining (Emission Reduction Fluid)»(/gmc/sierra-2500/2012-2012/remont/testing-diagnostics/#engine-controlsfuel-66l-lgh-lml-repair-instructions__fuel-tank-draining-emission-reduction-fluid) .
2. Remove the filler housing fasteners (1).
3. Remove the filler hose ground fastener (1).
4. Loosen the hose clamps (2).
5. Remove the fuel tank filler hose (3).

1. Install the fuel tank filler hose (3).
2. Tighten the hose clamps (2) to 6 N.m (53 lb in).
3. Tighten the filler hose ground fastener (1) to 10 N.m (89 lb in).
4. Tighten the filler housing fasteners (1) to 10 N.m (89 lb in)
5. Fill the fuel to the previous level.

Scheme 16

Engine Fuel Vacuum Switch Replacement

Fuel System Cleaning

Fungi and other microorganisms can survive and multiply in diesel fuel if water is present. The fungi can be present in any part of the fuel handling system. These fungi grow into long strings and will form into large globules. The growths appear slimy and are usually black, green, or brown. The fungi may grow anywhere in the fuel but are most plentiful where diesel fuel and water meet. As the fuel is agitated, when service station tanks are being filled, fungi are distributed throughout the tank and may be pumped into a vehicle.

Fungi use the fuel as their main energy supply and need only trace amounts of water and minerals. As they grow and multiply, they change fuel into water, sludge, acids, and products of metabolism. The most common symptom is fuel filter plugging; however, various metal components including the fuel sending unit, pipes, fuel injectors, and injection pump can corrode.

If fungi have caused fuel system contamination, use a diesel fuel biocide to sterilize the fuel system. Do not exceed the dosage recommended on the label. Discontinue the use of a biocide when towing a trailer. It is permissible to have biocide in the fuel when starting to tow, but do not add any biocide while towing.

Steam cleaning may be necessary if most of the fungus growth cannot be removed with biocides.

The presence of water or gasoline in diesel fuel may also cause injection pump and nozzle damage.

This procedure checks for the presence of water and gasoline in diesel fuel that may cause injection pump and nozzle damage.

Remove and inspect the fuel filter element.

1. If water, gasoline or fungi/bacteria are not present, end the inspection.
2. If water or fungi/bacteria are present, proceed to Cleaning Water from the Fuel System.
3. If gasoline is present, proceed to Cleaning Gasoline from the Fuel System.

Cleaning Water from the Fuel System

1. Disconnect the negative battery. Refer to «Battery Negative Cable Disconnection and Connection (TP2)»(/gmc/sierra-2500/2012-2012/remont/charging-system/#battery-charging-system-and-starting-system) , «Battery Negative Cable Disconnection and Connection (Single Battery)»(/gmc/sierra-2500/2012-2012/remont/charging-system/#battery-charging-system-and-starting-system) .
2. Remove the fuel sender assembly. Refer to «Fuel Tank Fuel Pump Module Replacement»(/gmc/sierra-2500/2012-2012/remont/testing-diagnostics/#engine-controlsfuel-66l-lgh-lml-repair-instructions__fuel-tank-fuel-pump-module-replacement) .
3. Inspect the fuel tank and the fuel sender for rust, fungi or bacteria. If there is rust, replace the rusted components.
4. Clean the inside of the fuel tank and the fuel sender with hot water.
5. Use compressed air in order to dry the fuel tank and the fuel sender.
6. Disconnect the ends of the following lines: The fuel filter inlet line (both ends) The transfer pump pressure line and suction line (if applicable) The fuel filter outlet line (both ends) The fuel filter drain The fuel return line (both ends)
7. Inspect each of the pipes and lines.
8. Replace any rusted pipes.
9. Clean the inside of the fuel filter housing.
10. Dry the fuel filter housing with compressed air.
11. Dry the inside of each line with low pressure air.
12. Disconnect the crankshaft position sensor.
13. Install a new fuel filter. Refer to «Fuel Filter Replacement»(/gmc/sierra-2500/2012-2012/remont/testing-diagnostics/#engine-controlsfuel-66l-lgh-lml-repair-instructions) .
14. Install the fuel sender assembly Refer to. «Fuel Tank Fuel Pump Module Replacement»(/gmc/sierra-2500/2012-2012/remont/testing-diagnostics/#engine-controlsfuel-66l-lgh-lml-repair-instructions__fuel-tank-fuel-pump-module-replacement) .
15. Add clean diesel fuel to the primary tank until the tank is 1/4 full.
16. Reconnect the following lines: The fuel filter inlet line The fuel filter outlet line The transfer pump pressure and suction (both ends) lines The fuel return line (tank end)
17. Connect the fuel filter drain to a line that flows into a clean metal container.
18. Connect the batteries.
19. Operate the fuel system hand primer at the fuel filter until clean fuel flows from the fuel filter drain into a metal container.
20. Close the fuel filter drain and remove the bleeder hose.
21. Install a hose on the fuel return line near the glow plug relay, and insert other end into a 7.6 liters (2 gallon) metal container.
22. Crank the engine for 15 second time intervals, with 1 minute cool-down periods. Continue until 3.8 liters (1 gallon) of fuel has passed into the container.
23. Connect the fuel return line.
24. Reconnect the crankshaft position sensor.
25. Start and run the engine.
26. Stop the engine.
27. Clean any fuel spillage from the engine.
28. Fill the fuel tank and add a biocide, if needed.

Cleaning Gasoline from the Fuel System

1. Drain the fuel tank.
2. Fill the fuel tank to 1/4 full.
3. Loosen the fuel filter drain and connect the filter to a hose that flows into a metal container.
4. Operate the fuel system hand primer at the fuel filter until clean fuel flows from the fuel filter drain into the metal container.
5. Hand tighten the fuel filter drain and disconnect the hose.
6. Install a hose on the fuel return line near the glow plug relay, and insert the other end into a 7.6 liters (2 gallon) metal container.
7. Crank the engine for 30 second time intervals, with 1 minute cool-down periods. Continue until 3.8 liters (1 gallon) of fuel has passed into the container.
8. Reconnect the fuel return line.
9. Attempt to start and run the engine for 15 minutes. If the engine does not start, operate the hand primer for 30 strokes, or until firm.
10. Stop the engine.
11. Clean any fuel spillage from the engine.
12. Clear the engine of any diagnostic trouble codes (DTCs).

Fuel Feed and Return Pipe Purging

1. Pump the primer (1) located on top of the fuel filter 30 times or until stiff.
2. Attempt to start and run the engine. If the engine does not start, repeat step 1.
3. Allow to run for 5 minutes at idle.
4. Check for fuel leaks.
5. Clear all engine diagnostic trouble codes (DTCs).

1. If LML, remove the rear exhaust gas recirculation valve cooler assembly. Refer to «Exhaust Gas Recirculation Valve Cooler Replacement»(/gmc/sierra-2500/2012-2012/remont/cooling-system-mechanical/#engine-cooling-system) .
2. Remove the right fuel injector feed pipes. Refer to «Fuel Injection Fuel Feed Pipe Replacement - Right Side»(/gmc/sierra-2500/2012-2012/remont/testing-diagnostics/#engine-controlsfuel-66l-lgh-lml-repair-instructions) .
3. Disconnect the high pressure fuel pipes (1).
4. Remove the fuel rail fasteners (1) and fuel injection fuel rail assembly (2).

1. Position the fuel injection fuel rail assembly (2) and install the fuel rail fasteners (1). Tighten to 25 N.m (18 lb ft)
2. Install the fuel rail feed pipe fittings (1) and tighten to 30 N.m (22 lb ft).
3. Install the right fuel injector feed pipes. Refer to «Fuel Injection Fuel Feed Pipe Replacement - Right Side»(/gmc/sierra-2500/2012-2012/remont/testing-diagnostics/#engine-controlsfuel-66l-lgh-lml-repair-instructions) .
4. If LML, install the rear exhaust gas recirculation valve cooler assembly. Refer to «Exhaust Gas Recirculation Valve Cooler Replacement»(/gmc/sierra-2500/2012-2012/remont/cooling-system-mechanical/#engine-cooling-system) .
5. Prime the fuel system. Refer to «Fuel System Priming»(/gmc/sierra-2500/2012-2012/remont/testing-diagnostics/#engine-controlsfuel-66l-lgh-lml-repair-instructions__fuel-system-priming) .
6. Start the engine. If the engine does not start, repeat the above step.
7. Inspect the fuel system for leaks.

1. Remove the exhaust gas recirculation cooler. Refer to «Exhaust Gas Recirculation Valve Cooler Replacement»(/gmc/sierra-2500/2012-2012/remont/cooling-system-mechanical/#engine-cooling-system) .
2. Remove the left fuel injector feed pipes. Refer to «Fuel Injection Fuel Feed Pipe Replacement - Left Side»(/gmc/sierra-2500/2012-2012/remont/testing-diagnostics/#engine-controlsfuel-66l-lgh-lml-repair-instructions) .
3. Disconnect the fuel pressure relief valve electrical connector (1).
4. Remove the high pressure fuel pipe (2).
5. Collapse the spring clamp and disconnect the fuel return hose (1).
6. Disconnect the fuel pressure sensor electrical connector (1).
7. Remove the fuel rail heat shield fasteners (1).
8. Remove the fuel injection rail fasteners (1).
9. Remove the heat shield (2) and fuel injection fuel rail assembly (3).

1. Install the fuel injection fuel rail assembly (3) and heat shield (2).
2. Install the fuel injection rail fasteners (1) and tighten to 25 (18 lb ft)
3. Install the fuel rail heat shield fasteners (1) and tighten to 25 (18 lb ft)
4. Connect the fuel pressure sensor electrical connector (1).
5. Collapse the spring clamp, and connect the fuel return hose (1).
6. Connector the fuel pressure relief valve electrical connector (1).
7. Install the high pressure fuel pipe (2) and tighten to 30 (22 lb ft)
8. Install the left fuel injector feed pipes. Refer to «Fuel Injection Fuel Feed Pipe Replacement - Left Side»(/gmc/sierra-2500/2012-2012/remont/testing-diagnostics/#engine-controlsfuel-66l-lgh-lml-repair-instructions) .
9. Install the exhaust gas recirculation cooler. Refer to «Exhaust Gas Recirculation Valve Cooler Replacement»(/gmc/sierra-2500/2012-2012/remont/cooling-system-mechanical/#engine-cooling-system) .
10. Prime the fuel system. Refer to «Fuel System Priming»(/gmc/sierra-2500/2012-2012/remont/testing-diagnostics/#engine-controlsfuel-66l-lgh-lml-repair-instructions__fuel-system-priming) .
11. Start the engine. If the engine does not start, repeat the above step.
12. Inspect the fuel system for fuel leaks.

Scheme 17

Fuel Injection Fuel Feed Manifold Replacement

Scheme 18

Fuel Pressure Regulator Replacement

Scheme 19

Fuel Pressure Relief Valve Replacement

1. Remove the center intake manifold. Refer to «Center Intake Manifold Replacement»(/gmc/sierra-2500/2012-2012/remont/mechanical/#engine-mechanical-66l-lgh-lml-repair-instructions-on-vehicle) .
2. Remove and reposition the high pressure fuel pipes from the fuel injection pump. Refer to «Fuel High Pressure Pipe Replacement - Rail to Rail»(/gmc/sierra-2500/2012-2012/remont/testing-diagnostics/#engine-controlsfuel-66l-lgh-lml-repair-instructions) , and «Fuel High Pressure Pipe Replacement - Pump to Rail»(/gmc/sierra-2500/2012-2012/remont/testing-diagnostics/#engine-controlsfuel-66l-lgh-lml-repair-instructions) .
3. Remove and reposition the indirect fuel injector feed pipe from the injection pump. Refer to «Fuel Feed Pipe Replacement (Pump to Indirect Fuel Injector)»(/gmc/sierra-2500/2012-2012/remont/testing-diagnostics/#engine-controlsfuel-66l-lgh-lml-repair-instructions) .
4. Disconnect the electrical connectors (1).
5. Collapse the hose clamps and remove the fuel return and fuel feed hoses (2).
6. Remove the engine cooling crossover housing «Thermostat Housing Crossover Replacement»(/gmc/sierra-2500/2012-2012/remont/cooling-system-mechanical/#engine-cooling-system) .
7. Remove the camshaft gear access hole plug (1).
8. Rotate the crankshaft until the fuel injection pump gear timing marks are aligned with camshaft gear timing marks.
9. Remove the fuel injection pump bolts (1) and (2).
10. Remove the turbocharger cooler return pipe bracket (3).
11. Remove the fuel injection pump (4).
12. Remove the fuel pressure regulator and inspect for metal debris on the end of the regulator tip. IMPORTANT: If any metal debris is found, replace the following components: fuel injection pump, fuel rails, fuel injectors, fuel return line assembly, all high pressure fuel pipes, indirect fuel injector and fuel feed pipes (pump to indirect fuel injector).

1. Rotate the crankshaft to align the camshaft gear timing marks with the center of the inspection hole
2. Lubricate the O-ring on the fuel injection pump adapter with engine oil.
3. Install the fuel injection pump and adapter assembly (4) so that the timing mark on the fuel pump gear (5) is aligned with the timing marks on the camshaft gear (6).
4. Install the turbocharger cooler return pipe bracket (3). CAUTION: Refer to «Fastener Caution»(/gmc/sierra-2500/2012-2012/remont/oem-general-information/#dangers-warnings-and-cautions__fastener-caution) .
5. Install the fuel injection pump bolts (1) and (2) and tighten to 25 N.m (18 lb ft).
6. Install the camshaft gear access hole plug (1) and tighten to 75 N.m (55 lb ft).
7. Connect the electrical connectors (1).
8. Collapse the hose clamps and install the fuel return and fuel feed hoses (2).
9. Install the engine cooling crossover housing «Thermostat Housing Crossover Replacement»(/gmc/sierra-2500/2012-2012/remont/cooling-system-mechanical/#engine-cooling-system) .
10. Install the indirect fuel injector feed pipe from the injection pump. Refer to «Fuel Feed Pipe Replacement (Pump to Indirect Fuel Injector)»(/gmc/sierra-2500/2012-2012/remont/testing-diagnostics/#engine-controlsfuel-66l-lgh-lml-repair-instructions) .
11. Install the high pressure fuel pipes from the fuel injection pump. Refer to «Fuel High Pressure Pipe Replacement - Rail to Rail»(/gmc/sierra-2500/2012-2012/remont/testing-diagnostics/#engine-controlsfuel-66l-lgh-lml-repair-instructions) , and «Fuel High Pressure Pipe Replacement - Pump to Rail»(/gmc/sierra-2500/2012-2012/remont/testing-diagnostics/#engine-controlsfuel-66l-lgh-lml-repair-instructions) .
12. Install the center intake manifold. Refer to «Center Intake Manifold Replacement»(/gmc/sierra-2500/2012-2012/remont/mechanical/#engine-mechanical-66l-lgh-lml-repair-instructions-on-vehicle) .

Fuel Injector Replacement (Left Side)

Special Tools

1. EN 47909 Injector Bore and Sleeve Cleaning Kit
2. EN-49774 Fuel Injector Puller

1. Remove the left side fuel injection fuel feed pipes. Refer to «Fuel Injection Fuel Feed Pipe Replacement - Left Side»(/gmc/sierra-2500/2012-2012/remont/testing-diagnostics/#engine-controlsfuel-66l-lgh-lml-repair-instructions)
2. Disconnect the fuel injector electrical connectors (1).
3. Disconnect and reposition the fuel return pipes (1).
4. Remove the fuel injector bracket bolts (1).
5. Install EN-49774 puller into the bolt hole in the fuel injector bracket.
6. Install a flare nut wrench onto EN-49774 puller, and work the tool outward until the injector releases from its seat.
7. Remove the EN-49774 puller.
8. Remove the fuel injectors (1) with the brackets (2).
9. Remove and discard the copper washer from the fuel injector bore.
10. Remove and discard the fuel injector O-ring from the injector.

Fuel Injector Cleaning and Inspection

Note. If reusing the old injectors perform the following

1. Use a soft bristle non-metallic brush and Top Engine Cleaner to remove any deposits from the nozzle tip (1) and the copper washer sealing area (2) before re-installation. Refer to «Adhesives, Fluids, Lubricants, and Sealers»(/gmc/sierra-2500/2012-2012/remont/testing-diagnostics/#engine-controlsfuel-66l-lgh-lml-specifications__adhesives-fluids-lubricants-and-sealers) .
2. Inspect the fuel injector nozzle tip (1) for any signs of discoloration (dark yellow, tan or blue) due to excessive heat.
3. Replace the injector if any damage is found.
4. Clean the fuel injector high pressure line.
5. Inspect the fuel injector line for excessive corrosion or damage to the sealing surfaces (1, 2). Replace the line if any damage is found.

Injector Bore Cleaning

Note. The procedure below will aid in the cleaning of carbon deposits from the injector sleeve during an injector replacement

1. Install the EN 47909-2 brush to the EN 47909-1 handle.
2. Insert the brush into the injector bore and rotate the handle in order to break loose any carbon deposits from the injector bore walls and the combustion deck hole.
3. Using compressed air, evacuate any debris from the injector bore.
4. Remove the radial brush from the handle assembly.
5. Install the EN 47909-3 brush to the En 47909-1 handle.
6. Insert the axial brush into the injector bore and rotate the handle while also applying a slight downward pressure, in order to force the brush ends into the bottom corners of the injector bore.
7. Using compressed air, evacuate any debris from the injector bore.
8. Lightly dampen EN 47909-20 swab with Top Engine Cleaner and wipe away any deposits from the injector bore. Refer to «Adhesives, Fluids, Lubricants, and Sealers»(/gmc/sierra-2500/2012-2012/remont/testing-diagnostics/#engine-controlsfuel-66l-lgh-lml-specifications__adhesives-fluids-lubricants-and-sealers) .
9. Inspect the injector bore for any deposits and repeat brushing if necessary.
10. If necessary, crank the engine in order to expel any solvent before starting the engine. Remove the glow plugs. Refer to «Glow Plug Replacement - Bank 1»(/gmc/sierra-2500/2012-2012/remont/testing-diagnostics/#engine-controlsfuel-66l-lgh-lml-repair-instructions) , and/or «Glow Plug Replacement - Bank 2»(/gmc/sierra-2500/2012-2012/remont/testing-diagnostics/#engine-controlsfuel-66l-lgh-lml-repair-instructions) . Disable the fuel system. Disconnect the crankshaft position (CKP) sensor electrical connector. Crank the engine in order to expel any excessive solvent. Using the cotton swabs supplied with the kit, wipe the injector bore clean of any solvent and/or debris. Connect the CKP sensor electrical connector. Enable the fuel system. Reinstall the glow plugs. Refer to «Glow Plug Replacement - Bank 1»(/gmc/sierra-2500/2012-2012/remont/testing-diagnostics/#engine-controlsfuel-66l-lgh-lml-repair-instructions) , and/or «Glow Plug Replacement - Bank 2»(/gmc/sierra-2500/2012-2012/remont/testing-diagnostics/#engine-controlsfuel-66l-lgh-lml-repair-instructions) .

1. Install a NEW copper washer to the fuel injector bore.
2. Install a NEW fuel injector O-ring to the injector.
3. Install the fuel injectors (1) with brackets (2).
4. Install the fuel injector bracket bolts and tighten to 30 (22 lb ft).
5. Reposition and connect and the fuel return pipes (1).
6. Connect the fuel injector electrical connectors (1).
7. If the fuel injectors were replaced, program the flow rate. Refer to «Fuel Injector Flow Rate Programming»(/gmc/sierra-2500/2012-2012/remont/testing-diagnostics/#engine-controlsfuel-66l-lgh-lml-repair-instructions) .
8. Prime the fuel system. Refer to «Fuel System Priming»(/gmc/sierra-2500/2012-2012/remont/testing-diagnostics/#engine-controlsfuel-66l-lgh-lml-repair-instructions__fuel-system-priming) .
9. Start the engine. If the engine stalls, repeat the above step.
10. Once the engine starts, inspect for fuel leaks.
11. If any or all fuel injectors were replaced, perform the fuel injector correction reset. Refer to «Fuel Injector Correction Reset»(/gmc/sierra-2500/2012-2012/remont/testing-diagnostics/#engine-controlsfuel-66l-lgh-lml-repair-instructions) .

Fuel Injector Replacement (Right Side)

Special Tools

1. EN 47909 Injector Bore and Sleeve Cleaning Kit
2. EN 49774 Fuel Injector Puller

For equivalent regional tools, refer to Special Tools (Diagnostic Tools Diesel) .

1. Remove the fuel filter bracket «Fuel Filter Bracket Replacement»(/gmc/sierra-2500/2012-2012/remont/testing-diagnostics/#engine-controlsfuel-66l-lgh-lml-repair-instructions) .
2. Remove the right side fuel injection fuel feed pipes. Refer to «Fuel Injection Fuel Feed Pipe Replacement - Right Side»(/gmc/sierra-2500/2012-2012/remont/testing-diagnostics/#engine-controlsfuel-66l-lgh-lml-repair-instructions) .
3. Disconnect the fuel injector electrical connectors (1).
4. Disconnect and reposition the fuel return pipes (1).
5. Remove the fuel injector bracket bolts (1).
6. Install EN 49774 puller into the bolt hole in the fuel injector bracket.
7. Install a flare nut wrench onto EN 49774 puller, and work the tool outward until the injector releases from its seat.
8. Remove the EN 49774 puller.
9. Remove the fuel injectors (1) with the brackets (2).
10. Remove and discard the copper washer from the fuel injector bore.
11. Remove and discard the fuel injector O-ring from the injector.

Note. If reusing the old injectors perform the following

1. Use a soft bristle non-metallic brush and Top Engine Cleaner to remove any deposits from the nozzle tip (1) and the copper washer sealing area (2) before re-installation. Refer to «Adhesives, Fluids, Lubricants, and Sealers»(/gmc/sierra-2500/2012-2012/remont/testing-diagnostics/#engine-controlsfuel-66l-lgh-lml-specifications__adhesives-fluids-lubricants-and-sealers) .
2. Inspect the fuel injector nozzle tip (1) for any signs of discoloration (dark yellow, tan or blue) due to excessive heat.
3. Replace the injector if any damage is found.
4. Clean the fuel injector high pressure line.
5. Inspect the fuel injector line for excessive corrosion or damage to the sealing surfaces (1, 2). Replace the line if any damage is found.

Note. The procedure below will aid in the cleaning of carbon deposits from the injector sleeve during an injector replacement

1. Install the EN-47909-2 brush to the EN-47909-1 handle.
2. Insert the brush into the injector bore and rotate the handle in order to break loose any carbon deposits from the injector bore walls and the combustion deck hole.
3. Using compressed air, evacuate any debris from the injector bore.
4. Remove the radial brush from the handle assembly.
5. Install the EN-47909-3 brush to the EN-47909-1 handle.
6. Insert the axial brush into the injector bore and rotate the handle while also applying a slight downward pressure, in order to force the brush ends into the bottom corners of the injector bore.
7. Using compressed air, evacuate any debris from the injector bore.
8. Lightly dampen EN-47909-20 swab with Top Engine Cleaner and wipe away any deposits from the injector bore. Refer to «Adhesives, Fluids, Lubricants, and Sealers»(/gmc/sierra-2500/2012-2012/remont/testing-diagnostics/#engine-controlsfuel-66l-lgh-lml-specifications__adhesives-fluids-lubricants-and-sealers) .
9. Inspect the injector bore for any deposits and repeat brushing if necessary.
10. If necessary, crank the engine in order to expel any solvent before starting the engine. Remove the glow plugs. Refer to «Glow Plug Replacement - Bank 1»(/gmc/sierra-2500/2012-2012/remont/testing-diagnostics/#engine-controlsfuel-66l-lgh-lml-repair-instructions) , and/or «Glow Plug Replacement - Bank 2»(/gmc/sierra-2500/2012-2012/remont/testing-diagnostics/#engine-controlsfuel-66l-lgh-lml-repair-instructions) . Disable the fuel system. Disconnect the crankshaft position (CKP) sensor electrical connector. Crank the engine in order to expel any excessive solvent. Using the cotton swabs supplied with the kit, wipe the injector bore clean of any solvent and/or debris. Connect the CKP sensor electrical connector. Enable the fuel system. Reinstall the glow plugs. Refer to «Glow Plug Replacement - Bank 1»(/gmc/sierra-2500/2012-2012/remont/testing-diagnostics/#engine-controlsfuel-66l-lgh-lml-repair-instructions) , and/or «Glow Plug Replacement - Bank 2»(/gmc/sierra-2500/2012-2012/remont/testing-diagnostics/#engine-controlsfuel-66l-lgh-lml-repair-instructions) .

1. Install a NEW copper washer to the fuel injector bore.
2. Install a NEW fuel injector O-ring to the injector.
3. Install the fuel injectors (1) with brackets (2).
4. Install the fuel injector bracket bolts and tighten to 30 (22 lb ft).
5. Reposition and connect and the fuel return pipes (1).
6. Connect the fuel injector electrical connectors (1).
7. If the fuel injectors were replaced, program the flow rate. Refer to «Fuel Injector Flow Rate Programming»(/gmc/sierra-2500/2012-2012/remont/testing-diagnostics/#engine-controlsfuel-66l-lgh-lml-repair-instructions) .
8. Prime the fuel system. Refer to «Fuel System Priming»(/gmc/sierra-2500/2012-2012/remont/testing-diagnostics/#engine-controlsfuel-66l-lgh-lml-repair-instructions__fuel-system-priming) .
9. Start the engine. If the engine stalls, repeat the above step.
10. Once the engine starts, inspect for fuel leaks.
11. If any or all fuel injectors were replaced, perform the fuel injector correction reset. Refer to «Fuel Injector Correction Reset»(/gmc/sierra-2500/2012-2012/remont/testing-diagnostics/#engine-controlsfuel-66l-lgh-lml-repair-instructions) .

Scheme 20

Fuel Injection Fuel Rail Fuel Pressure Sensor Replacement

Indirect Fuel Injector Replacement

Special Tools

CH-49736 Hydrocarbon Injector Quick Connect Release Tool

For equivalent regional tools, refer to Special Tools (Diagnostic Tools Diesel) .

1. Remove the right side wheelhouse liner. Refer to «Front Wheelhouse Liner Replacement - Right Side (GMC)»(/gmc/sierra-2500/2012-2012/remont/frames-subframes-crossmembers/#frame-and-underbody) , «Front Wheelhouse Liner Replacement - Right Side (Chevrolet)»(/gmc/sierra-2500/2012-2012/remont/frames-subframes-crossmembers/#frame-and-underbody) .
2. Remove the indirect fuel injector fasteners (1, 2).
3. Remove the indirect fuel injector retainer (1) from the fitting.
4. Remove the indirect fuel injector (2) using the CH-49736 tool.
5. Remove the indirect injector fitting.

1. Install the indirect fuel injector retainer (1) to the fitting.
2. Install the indirect fuel injector (2) and tighten the fitting to 45 N.m (33 lb ft).
3. Install the indirect fuel injector fasteners (1, 2) to 25 N.m (18 lb ft).
4. Install the right side wheelhouse liner. Refer to «Front Wheelhouse Liner Replacement - Right Side (GMC)»(/gmc/sierra-2500/2012-2012/remont/frames-subframes-crossmembers/#frame-and-underbody) , «Front Wheelhouse Liner Replacement - Right Side (Chevrolet)»(/gmc/sierra-2500/2012-2012/remont/frames-subframes-crossmembers/#frame-and-underbody) .
5. Perform the Diesel Particulate Filter Regeneration. Refer to «Diesel Particulate Filter (DPF) Regeneration Enable»(/gmc/sierra-2500/2012-2012/remont/testing-diagnostics/#engine-controlsfuel-66l-lgh-lml-repair-instructions__diesel-particulate-filter-dpf-regeneration-enable) .

Scheme 21

Fuel Temperature Sensor Replacement (Fuel Rail Return)

Scheme 22

Fuel Temperature Sensor Replacement (Injection Pump)

Scheme 23

Glow Plug Control Module Bracket Replacement

Scheme 24

Glow Plug Replacement - Bank 1

Scheme 25

Glow Plug Replacement - Bank 2

Scheme 26

Glow Plug Control Module Replacement

Cleaning Procedure

1. Ensure the ignition is OFF.
2. Raise and support the vehicle. Refer to «Lifting and Jacking the Vehicle»(/gmc/sierra-2500/2012-2012/remont/ignition-switchsteering-lock/#general-information__lifting-and-jacking-the-vehicle) .
3. Using only a low pressure clean water hose, spray the upper surfaces of the Diesel Exhaust Fluid (DEF) Tank (1) and pump supply module, the injection hose, and the fill hose assembly, to remove all dirt and debris.
4. Using only a low pressure air wand or air gun, direct air along the same surfaces to both dry and remove any further contaminants.
5. Using a clean white shop towel, carefully dry connections and joints by hand to ensure dryness and cleanliness.

1. Drain the emission reduction fluid tank. Refer to «Fuel Tank Draining (Gasoline)»(/gmc/sierra-2500/2012-2012/remont/testing-diagnostics/#engine-controlsfuel-66l-lgh-lml-repair-instructions__fuel-tank-draining-gasoline) , «Fuel Tank Draining (Emission Reduction Fluid)»(/gmc/sierra-2500/2012-2012/remont/testing-diagnostics/#engine-controlsfuel-66l-lgh-lml-repair-instructions__fuel-tank-draining-emission-reduction-fluid) .
2. Remove the DEF tank. Refer to «Emission Reduction Fluid Tank Replacement»(/gmc/sierra-2500/2012-2012/remont/testing-diagnostics/#engine-controlsfuel-66l-lgh-lml-repair-instructions) .

Disassembly Procedure

1. Remove the DEF supply pump module shield (1).
2. Remove the DEF supply pump module insulators (1).
3. Note the routing of the DEF wiring jumper harness.
4. Disconnect the DEF wiring jumper harness connectors from the pump (1), pressure sensor (2), and reverting valve (3).
5. Remove the 3 DEF supply pump module retaining bolts (1).
6. Carefully lift the DEF supply pump module (2) to remove from the reservoir cover.
7. Carefully remove & discard the supply pump to reservoir cover o-ring seals (1). The seals will typically remain in the reservoir cover, but may be on the underside of the supply pump.
8. Wipe away any dried DEF crystallization residue from the reservoir cover supply pump ports (2).

1. Carefully install the new supply pump to reservoir cover o-ring seals. Position the smaller o-ring seal (1) over the port on the underside of the supply pump, and position the larger o-ring seal (2) into the port on the reservoir cover.
2. Position the supply pump module (2) onto the reservoir cover and carefully press down into place.
3. Install the 3 supply pump module retaining bolts (1), and tighten the bolts to 5 N.m (3.7 lb in).
4. Connect the DEF wiring jumper harness connectors to the pump (1), pressure sensor (2), and reverting valve (3).
5. Install the DEF supply pump module insulators (1).
6. Install the DEF supply pump module shield (1).
7. Install the DEF tank. Refer to «Emission Reduction Fluid Tank Replacement»(/gmc/sierra-2500/2012-2012/remont/testing-diagnostics/#engine-controlsfuel-66l-lgh-lml-repair-instructions) .
8. Fill the DEF tank with approved DEF fluid.
9. With system operational, inspect for DEF fluid leaks.

Scheme 27

Emission Reduction Fluid Injector Replacement

Scheme 28

Emission Reduction Fluid Exhaust Front Pipe Injector Supply Pipe Replacement

Scheme 29

Emission Reduction Fluid Tank Opening Filler Replacement

Emission Reduction Fluid Tank Reservoir Replacement

Special Tools

CH-38879-B Fuel Pump Module Wrench

1. Ensure the ignition is OFF.
2. Raise and support the vehicle. Refer to «Lifting and Jacking the Vehicle»(/gmc/sierra-2500/2012-2012/remont/ignition-switchsteering-lock/#general-information__lifting-and-jacking-the-vehicle) .
3. Using only a Low pressure clean water hose, spray the upper surfaces of the Diesel Exhaust Fluid (DEF) Tank and pump supply module, the injection hose, and the fill hose assembly, to remove all dirt and debris.
4. Using only a Low pressure air wand or air gun, direct air along the same surfaces to both dry and remove any further contaminants.
5. Using a clean white shop towel, carefully dry connections and joints by hand to ensure dryness and cleanliness.

1. Drain the emission reduction fluid tank. Refer to «Fuel Tank Draining (Gasoline)»(/gmc/sierra-2500/2012-2012/remont/testing-diagnostics/#engine-controlsfuel-66l-lgh-lml-repair-instructions__fuel-tank-draining-gasoline) , «Fuel Tank Draining (Emission Reduction Fluid)»(/gmc/sierra-2500/2012-2012/remont/testing-diagnostics/#engine-controlsfuel-66l-lgh-lml-repair-instructions__fuel-tank-draining-emission-reduction-fluid) .
2. Remove the DEF tank. Refer to «Emission Reduction Fluid Tank Replacement»(/gmc/sierra-2500/2012-2012/remont/testing-diagnostics/#engine-controlsfuel-66l-lgh-lml-repair-instructions) .
3. Place the DEF tank assembly in a suitable, clean work area.
4. Remove the DEF tank supply pump module. Refer to «Emission Reduction Fluid Supply Pump Module Replacement»(/gmc/sierra-2500/2012-2012/remont/testing-diagnostics/#engine-controlsfuel-66l-lgh-lml-repair-instructions) .

1. Disconnect the DEF wiring jumper harness connectors from the control module assembly (1), and from the reservoir heater connector (2).
2. Release the jumper harness retaining clips from the supply module lock ring (2). Release the clip retaining tab (1) and slide the clip upward to remove.
3. Remove the jumper harness.
4. Release the reservoir heater connector (1) from the retainer on the DEF tank. Carefully depress the lock tab (2) of the tank retainer, while sliding the connector forward.
5. Release the control module assembly (1) from the retainer on the DEF tank. Carefully depress the lock tab (2) on the underside of the control module, while sliding the module sideways away from the supply pump.
6. Carefully remove & discard the supply pump to reservoir cover o-ring seals (1). The seals will typically remain in the reservoir cover, but may be on the underside of the supply pump.
7. Wipe away any dried DEF crystallization residue from the reservoir cover supply pump.
8. Rotate the reservoir vent (1) inward.
9. Position the CH-38879-B Fuel Pump Module Wrench (3), DEF supply pump module wrench, onto the supply module lock ring (4). Ensure the posts of the tool are positioned to fit securely onto opposing ribs of the lock ring.
10. Plug the reservoir cover to supply pump ports (1, 2) to protect from dirt & debris.
11. Using a breaker bar attached to CH-38879-B Fuel Pump Module Wrench loosen the lock ring. Reposition CH-38879-B Fuel Pump Module Wrench as necessary to prevent damage to the reservoir level sensor and heater wiring.
12. Carefully remove the lock ring over the reservoir wiring.
13. Carefully lift the reservoir cover (1) up just enough to free it from the seal (2).
14. Carefully work the reservoir seal (1) up and out of the neck of the DEF tank.
15. Carefully remove the seal (1) from around the reservoir cover and the reservoir wiring.
16. Using finger pressure only to rotate the reservoir assembly, position fingers against the level sensor bulkhead (1) and the ledge opposite the bulkhead (2).
17. Rotate the reservoir assembly (1) counterclockwise to release the lock tabs (2) at the bottom of the DEF tank, then lift the reservoir (3) out of the tank.
18. If the reservoir assembly is to be reused, inspect the DEF filter (1) at the bottom of the reservoir for damage, and for dirt and debris, other than dried DEF crystallization residue.
19. To remove dried DEF crystallization residue, use only a Low pressure clean water hose to spray the applicable surfaces of the reservoir assembly. Dried DEF crystallization residue will flush away with clean water.
20. Replace the DEF filter as necessary.
21. Wipe away any dried DEF crystallization residue from the tank seal.
22. Inspect the lower portion of the tank seal for deformity; taking a deeper set shape to the reservoir step (1), rather than returning to a mild shape for the reservoir step (1). Replace the seal if it is deformed.
23. Inspect the bottom of the DEF tank (1) for the presence of dirt and debris, and dried DEF crystallization residue.
24. If dirt and debris - other than dried DEF crystallization - are present inside the DEF tank, and if the reservoir is to be reused, replace the DEF filter at the bottom of the reservoir.
25. If dirt, debris, and/or dried DEF crystallization residue are present inside the DEF tank; using only a Low pressure clean water hose, spray the applicable surfaces inside the DEF tank. Dried DEF crystallization residue will flush away with clean water.
26. Using a suitable Clean, blunt object, carefully depress and hold open, the flapper valve (1) at the back of the DEF tank fill port.
27. While keeping the fill port open, pour out the contents of the tank into a suitable container for disposal.
28. Repeat steps 25-27 until the inside of the DEF tank is free of dirt, debris, and/or dried DEF crystallization residue.

Assembly Procedure

1. Align the reservoir lock tabs (1) to the reservoir retainer at the bottom of the DEF tank, and carefully lower the reservoir (2) into position.
2. Using finger pressure only to rotate the reservoir assembly, position fingers against the level sensor bulkhead (1) and the ledge opposite the bulkhead (2).
3. Rotate the reservoir clockwise to secure the lock tabs (1) at the bottom of the DEF tank. An audible "click" noise will be heard when the lock position is reached.
4. Carefully slide the seal (1) over the reservoir wiring and around the reservoir cover.
5. Carefully work the reservoir seal (1) down into the neck of the DEF tank, while simultaneously working the seal lower lip around the outside of the reservoir.
6. Inspect to ensure the seal is fully seated and to ensure the lower lip of the seal (1) is positioned correctly around the outside of the reservoir (2).
7. Carefully position the reservoir cover (1) to the tank seal (2).
8. Position the reservoir cover so that the cover alignment mark arrow (1) will be centered between the 2 long alignment marks (2) on the top of the tank.
9. Carefully slide the lock ring over the reservoir wiring.
10. Remove the plugs from the supply ports (1, 2).
11. Hand tighten the reservoir lock ring only until snug.
12. Position the CH-38879-B Fuel Pump Module Wrench (3), DEF supply pump module wrench, onto the supply module lock ring (4). Ensure the posts of the tool are positioned to fit securely onto opposing ribs of the lock ring.
13. Using a torque wrench attached to CH-38879-B Fuel Pump Module Wrench tighten the lock ring. Reposition CH-38879-B Fuel Pump Module Wrench as necessary to prevent damage to the reservoir level sensor and heater wiring. Tighten the lock ring to 85 Nm (63 lb ft).
14. Rotate the reservoir vent (1) outward.
15. Carefully install the new supply pump to reservoir cover o-ring seals. Position the smaller o-ring seal (1) over the port on the underside of the supply pump, and position the larger o-ring seal (2) into the port on the reservoir cover.
16. Install the DEF tank supply pump module. Refer to «Emission Reduction Fluid Supply Pump Module Replacement»(/gmc/sierra-2500/2012-2012/remont/testing-diagnostics/#engine-controlsfuel-66l-lgh-lml-repair-instructions) .
17. Align the control module assembly (1) retaining slots to the mating slots on the retainer. Slide the module sideways toward the pump to secure the lock tab (2) on the underside of the module.
18. Align the reservoir heater connector (1) retaining slots to the mating slots on the retainer. Slide the connector into place to secure the lock tab (2) of the tank retainer.
19. Install the DEF wiring jumper harness into position as noted prior to removal.
20. Secure the jumper harness retaining clips to the supply module lock ring in the locations noted prior to removal. Slide the clip (2) downward to secure the clip retaining tab (1).
21. Connect the DEF wiring jumper harness connectors to the pump (1), pressure sensor (2), reverting valve (3), control module assembly (4), and to the reservoir heater connector (5).

1. Install the DEF tank (1). Refer to «Emission Reduction Fluid Tank Replacement»(/gmc/sierra-2500/2012-2012/remont/testing-diagnostics/#engine-controlsfuel-66l-lgh-lml-repair-instructions) .
2. Install the DEF line (2).
3. Fill the DEF tank with approved DEF fluid.
4. With system operational, inspect for DEF fluid leaks.

1. Ensure the ignition is OFF.
2. Raise and support the vehicle. Refer to «Lifting and Jacking the Vehicle»(/gmc/sierra-2500/2012-2012/remont/ignition-switchsteering-lock/#general-information__lifting-and-jacking-the-vehicle) .
3. Using only a Low pressure clean water hose, spray the upper surfaces of the Diesel Exhaust Fluid (DEF) Tank and pump supply module, the injection hose, and the fill hose assembly, to remove all dirt and debris.
4. Using only a Low pressure air wand or air gun, direct air along the same surfaces to both dry and remove any further contaminants.
5. Using a clean white shop towel, carefully dry connections and joints by hand to ensure dryness and cleanliness.
6. Drain the emission reduction fluid tank. Refer to «Fuel Tank Draining (Gasoline)»(/gmc/sierra-2500/2012-2012/remont/testing-diagnostics/#engine-controlsfuel-66l-lgh-lml-repair-instructions__fuel-tank-draining-gasoline) , «Fuel Tank Draining (Emission Reduction Fluid)»(/gmc/sierra-2500/2012-2012/remont/testing-diagnostics/#engine-controlsfuel-66l-lgh-lml-repair-instructions__fuel-tank-draining-emission-reduction-fluid) .
7. Disconnect the filler pipe and vent pipe from the tank. Refer to «Emission Reduction Fluid Tank Opening Filler Replacement»(/gmc/sierra-2500/2012-2012/remont/testing-diagnostics/#engine-controlsfuel-66l-lgh-lml-repair-instructions) .
8. Cap both the vent hose and filler hose. Also cap the filler ports to prevent possible contamination.
9. Support the tank shield with a suitable jack. Remove the fuel tank shield fasteners (1) and remove the tank shield (2).
10. Remove the lower insulator (1).
11. Support the tank with a suitable jack. Remove the fuel tank strap fasteners (1) and remove the tank straps.
12. Lower the tank enough to access and disconnect the electrical connectors (1) and the injection hose port (2) by squeezing both sides.
13. Cap both the injection hose fitting and the port of the supply pump.
14. Lower the tank (1) with a suitable jack.

1. Install the tank (1) with a suitable jack.
2. Raise the tank enough to access and connect the electrical connectors (1) and the injection hose port (2).
3. Remove the caps for the injection hose fitting and the port of the supply pump.
4. Install the fuel tank strap fasteners (1) and tighten to 22 N.m (16 lb ft).
5. Install the lower insulator (1).
6. Place the outer tabs of the shield (2) onto the fuel tank straps hooks and then push the inner tabs up to the frame.
7. Install the fuel tank shield fasteners (1) and tighten to 12 N.m (9 lb ft).
8. In order to clear the DEF lamp, allow the engine to reach normal operating temperature. Drive the vehicle to 32-48 km/h (20-30 mph) until the DEF lamp turns OFF automatically.

Scheme 30

Crankshaft Position Sensor Replacement

Scheme 31

Camshaft Position Sensor Replacement

Scheme 32

Exhaust Gas Recirculation Valve Replacement (LGH)

Scheme 33

Exhaust Gas Recirculation Valve Replacement (LML)

Scheme 34

Exhaust Gas Recirculation Cooler Bypass Valve Replacement

Scheme 35

Exhaust Gas Recirculation Valve Temperature Sensor Replacement - Position 1

Scheme 36

Exhaust Gas Recirculation Valve Temperature Sensor Replacement - Position 2

Scheme 37

Exhaust Pressure Differential Sensor Replacement

Scheme 38

Exhaust Pressure Differential Sensor Pipe Replacement

Scheme 39

Exhaust Temperature Sensor Replacement - Position 1

Scheme 40

Exhaust Temperature Sensor Replacement - Position 2

Scheme 41

Exhaust Temperature Sensor Replacement - Position 3

Scheme 42

Exhaust Temperature Sensor Replacement - Position 4

1. Remove the rear exhaust gas recirculation (EGR) valve cooler. Refer to «Exhaust Gas Recirculation Valve Cooler Replacement»(/gmc/sierra-2500/2012-2012/remont/cooling-system-mechanical/#engine-cooling-system) .
2. Remove the turbocharger oil feed pipe banjo bolt and washer.
3. Reposition the turbocharger oil feed pipe out of the way.
4. Disconnect the engine wiring harness electrical connector from the turbocharger vane control solenoid valve.
5. Remove the turbocharger vane control solenoid valve bracket bolt (1) and bracket (2).
6. Remove the turbocharger vane control solenoid valve (3) from the turbocharger.

1. Install the turbocharger vane control solenoid valve (3) to the turbocharger.
2. Install the turbocharger vane control solenoid valve bracket (2) and bolt (1) and tighten to 23 N.m (18 lb ft).
3. Connect the engine wiring harness electrical connector to the turbocharger vane control solenoid valve.
4. Position the turbocharger oil feed pipe to the turbocharger.
5. Install a NEW turbocharger oil feed pipe washer and the banjo bolt and tighten to 34 N.m (25 lb ft).
6. Install the rear EGR valve cooler. Refer to «Exhaust Gas Recirculation Valve Cooler Replacement»(/gmc/sierra-2500/2012-2012/remont/cooling-system-mechanical/#engine-cooling-system) .
7. Perform the turbocharger learn procedure. Refer to «Turbocharger Learn»(/gmc/sierra-2500/2012-2012/remont/testing-diagnostics/#engine-controlsfuel-66l-lgh-lml-repair-instructions__turbocharger-learn) .

Scheme 43

Turbocharger Vane Position Sensor Replacement

Turbocharger Learn

The engine control module (ECM) performs the turbocharger (TC) learn procedure automatically when the engine coolant temperature (ECT) is least 72°C (162°F). After each ignition cycle, and before the enable criteria have been met, the ECM will use the previously learned value. If the ECM does not have a previously learned value, it will default to a stored calibrated value. The ECM will use this value until the enable criteria have been met. It will then perform this procedure to learn the new value. If the ECM attempts to perform the TC Learn procedure and fails, DTC P003A, P2598 or P2599 may set.

If a TC Learn is not performed after a related turbocharger repair, the ECM will use a stored vane position value that may be invalid. The ECM may then cause a diagnostic to fail and set an invalid DTC. Certain enable criteria must be met for the ECM to perform this procedure.

The turbocharger learn procedure is required when any of the following service procedures have been performed

1. Turbocharger vane position control solenoid valve replacement
2. Turbocharger vane position sensor replacement
3. ECM replacement
4. Turbocharger replacement
5. Any service that disturbs the turbocharger components

Learn Procedure With the Tech 2

Note. Once the enable conditions have been met the throttle must remain at idle. Do not change the accelerator pedal position (APP) during this procedure.

1. The following conditions must be met for the ECM to perform the turbocharger learn procedure: The air conditioning (A/C) system is OFF. The vehicle is in Park or Neutral. Start and idle the engine. The ECT is greater than 40°C (104°F).
2. After the enable conditions have been met and the engine idle is stabilized, enter the TC Learn Output function from the Module Setup Menu. Command the TC Learn ON for at least 5 s, then command it OFF. The system should have learned the new turbocharger position. The TC Vane Position Learn Status parameter should have toggled from In Progress to TC Learned.

Scheme 44

Air Cleaner Air Restriction Indicator Replacement

Scheme 45

Air Cleaner Element Replacement

Scheme 46

Air Cleaner Assembly Replacement

Scheme 47

Air Cleaner Outlet Duct Replacement

Scheme 48

Turbocharger Air Inlet Adapter Replacement

Scheme 49

Charge Air Cooler Inlet Pipe Replacement

Scheme 50

Charge Air Cooler Outlet Pipe Replacement

1. Remove the upper tie bar. Refer to «Front End Upper Tie Bar Replacement»(/gmc/sierra-2500/2012-2012/remont/exterior-body-panels/#bolted-exterior-body-panels-and-closures) .
2. Remove the charge air cooler inlet and outlet pipes. Refer to «Charge Air Cooler Inlet Pipe Replacement»(/gmc/sierra-2500/2012-2012/remont/testing-diagnostics/#engine-controlsfuel-66l-lgh-lml-repair-instructions) , and «Charge Air Cooler Outlet Pipe Replacement»(/gmc/sierra-2500/2012-2012/remont/testing-diagnostics/#engine-controlsfuel-66l-lgh-lml-repair-instructions) .
3. Remove the radiator. Refer to «Radiator Replacement (LGH, LML)»(/gmc/sierra-2500/2012-2012/remont/cooling-system-mechanical/#engine-cooling-system) .
4. Remove the charge air cooler bolts. NOTE: Do not damage the charged air cooler fins while removing.
5. Remove the charge air cooler. Disengage the bottom mounts from the radiator support. Remove the left side from the radiator support. Angle up the right side and rotate in order to remove.
6. Clean the charge air cooler by flushing with mild soap and water. Do not use stream pressure to clean.
7. Inspect the charge air cooler for the following damage: Damaged fins Cracked or distorted hose connections Broken or loose welds Leaks in the core or the tank connections
8. Replace the charge air cooler if damage is found.
9. Inspect the charged air cooler mounting insulators and replace if required.

1. Install the charge air cooler. Angle in the left side. Slide to the left. Move in the right side. Position bottom insulators in the radiator support. CAUTION: Refer to «Fastener Caution»(/gmc/sierra-2500/2012-2012/remont/oem-general-information/#dangers-warnings-and-cautions__fastener-caution) .
2. Install the charge air cooler bolts. Tighten Tighten the bolts to 21 N.m (15 lb ft).
3. Install the radiator. Refer to «Radiator Replacement (LGH, LML)»(/gmc/sierra-2500/2012-2012/remont/cooling-system-mechanical/#engine-cooling-system) .
4. Install the charge air cooler inlet and outlet pipes. Refer to «Charge Air Cooler Inlet Pipe Replacement»(/gmc/sierra-2500/2012-2012/remont/testing-diagnostics/#engine-controlsfuel-66l-lgh-lml-repair-instructions) , and «Charge Air Cooler Outlet Pipe Replacement»(/gmc/sierra-2500/2012-2012/remont/testing-diagnostics/#engine-controlsfuel-66l-lgh-lml-repair-instructions) .
5. Install the upper tie bar. Refer to «Front End Upper Tie Bar Replacement»(/gmc/sierra-2500/2012-2012/remont/exterior-body-panels/#bolted-exterior-body-panels-and-closures) .
6. If the scan tool DPF Soot Mass is less than 30 grams, enable the DPF. Refer to «Diesel Particulate Filter (DPF) Regeneration Enable»(/gmc/sierra-2500/2012-2012/remont/testing-diagnostics/#engine-controlsfuel-66l-lgh-lml-repair-instructions__diesel-particulate-filter-dpf-regeneration-enable) .
7. If the scan tool DPF Soot Mass is 30 grams or greater, refer to «Diesel Particulate Filter (DPF) Service Regeneration»(/gmc/sierra-2500/2012-2012/remont/testing-diagnostics/#engine-controlsfuel-66l-lgh-lml-repair-instructions) .

See also:
• Control Module References
• Glow Plug Control Module Programming and Setup (LGH or LML)
• Diagnostic Trouble Code (DTC) List - Vehicle
• Diagnostic Repair Verification
• Symptoms - Vehicle
• Exhaust Aftertreatment System Description
• Exhaust Particulate Filter Replacement (43 Series)
• Cooling System Draining and Filling (Static Fill)
• Cooling System Draining and Filling (Vac-N-Fill Diesel)
• Fastener Caution
• Battery Positive Junction Block Cable Replacement (Air Intake Heater - Diesel)
• Adhesives, Fluids, Lubricants, and Sealers
• Lifting and Jacking the Vehicle
• Gasoline/Gasoline Vapors Warning
• Fuel Pressure Relief (Without CH-48027)
• Fuel Pressure Relief (CH-48027)
• Safety Glasses and Compressed Air Warning
• Fuel and Evaporative Emission Hose/Pipe Connection Cleaning Caution
• Relieving Fuel Pressure Warning
• Fuel Pipe Fitting Warning
• Front Wheelhouse Liner Replacement - Right Side (GMC)
• Fuel Tank Strap Fastener Caution
• Special Tools (Diagnostic Tools Diesel)
• Exhaust Gas Recirculation Valve Cooler Replacement
• Turbocharger Replacement (LGH)
• Component Fastener Tightening Caution
• Fan Clutch Replacement (Diesel)
• Air Conditioning Compressor Replacement (LGH, LML)
• Front End Upper Tie Bar Replacement
• Turbocharger Learn
• Crankshaft Position Reluctor Wheel Learn
• Diesel Particulate Filter (DPF) Regeneration Enable
• Water-in-Fuel Draining
• Fuel System Priming
• Fuel Tank Fuel Pump Module Replacement
• Fuel Tank Draining (Gasoline)
• Fuel Tank Draining (Emission Reduction Fluid)
• Metal Collar Quick Connect Fitting Service