Engine Controls and Fuel - 6.6l - Troubleshooting & Diagnosis Chevrolet Cab & Chassis Silverado 3500 HD

Diagnostic Instructions

1. Perform the «Diagnostic System Check - Vehicle»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/oem-general-information/#vehicle-diagnostic-information__diagnostic-system-check-vehicle) prior to using this diagnostic procedure.
2. Review «Strategy Based Diagnosis»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/oem-general-information/#vehicle-diagnostic-information__strategy-based-diagnosis) for an overview of the diagnostic approach.
3. «Diagnostic Procedure Instructions»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/oem-general-information/#vehicle-diagnostic-information__diagnostic-procedure-instructions) provide an overview of each diagnostic category.

Symptoms Description

Symptoms covers conditions that are not covered by DTCs. Certain conditions can cause multiple symptoms. These conditions are listed together under Symptoms Testing. Conditions that may only cause specific symptoms are listed separately under Additional Symptoms Testing. Perform the Symptoms Testing before using the Additional Symptoms Testing.

Symptoms Verification

Before using the Symptom tables, perform the following inspections

1. Ensure that the engine control module (ECM) and malfunction indicator lamp (MIL) are operating correctly.
2. Ensure that there are no DTCs that are stored.
3. Ensure that the scan tool data is within a normal operating range. Refer to «Control Module References»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/communication-devices/#programming-and-setup-all-systems__control-module-references) for scan tool information.
4. Verify the customer concern.
5. Perform the Visual/Physical Inspection in this section. The visual/physical inspection is extremely important, and can lead to correcting a condition without additional testing. It may also help reveal the cause of an intermittent condition.

Identifying Intermittent Conditions

Many intermittent conditions occur with harness or connector movement due to engine torque, rough pavement, vibration or physical movements of a component. Refer to the following for a list of issues that may cause an intermittent condition

1. Moisture and water intrusion in connectors, terminals, and components
2. Incomplete connector mating
3. Poor terminal contact
4. High circuit or component resistance-High resistance can include any resistance, regardless of the amount, which can interrupt the operation of the component.
5. Harness that is too short or tight.
6. Wire insulation that is chaffed or cut.
7. High or low ambient temperature
8. High or low engine coolant temperatures
9. High underhood temperatures
10. Heat build up in component or circuit due to circuit resistance, poor terminal contact, or high electrical load
11. High or low system voltage
12. High vehicle load conditions
13. Rough road surfaces
14. Electro-magnetic interference (EMI)/circuit interference from relays, solenoids or other electrical surge
15. Incorrect installation of aftermarket, add on accessories

Visual/Physical Check

1. Ensure that the control module grounds are clean, tight, and correctly located. Refer to «Component Connector End Views»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/body-electrical/#wiring-systems-and-power-management-diagnostic-starting-point-connector-end-views) .
2. Ensure that the air filter is clean and free from restrictions.
3. Ensure that there is no water intrusion in connectors terminals and components.
4. Inspect the air intake ducts for the following conditions: Collapsed Damaged areas Looseness Incorrect installation Leaking
5. Inspect for air leaks at the intake AIR valve, the intake AIR heater, the MAF sensor and intake manifold sealing surfaces.
6. Inspect the wiring harness for the following conditions: Poor connections Pinches Cuts
7. Inspect for loose, damaged, unseated, or missing sensors/components.
8. Inspect the terminals for corrosion and correct contact.

Symptoms Testing

Note. Cuts Out/Misses, Hard Start, Hesitation/Sag/Stumble, Lack of Power/Sluggishness/Sponginess, Poor Fuel Economy, Rough, Unstable, or Incorrect Idle and Stalling, Fuel Knock/Combustion Noise, or Surges/Chuggles Excessive Smoke (Black), Excessive Smoke (White), Excessive Smoke (Gray or Blue).

Test Procedure

1. Test for the following conditions: The sensor systems for the following: Inspect the mass air flow (MAF) sensor for obstruction, contamination, and damage. Idle the engine and observe the Actual Fuel Rail Pressure and the Desired Fuel Rail Pressure parameters. If the pressure difference is more than 2 MPa, a fuel control issue may exist. Inspect for the EGR valve sticking open. Command the valve to 20%. Desired and actual position should not be more than 3% different. Inspect the CKP sensor reluctor wheel. Remove the CKP sensor and attempt to move the reluctor wheel front to back or side to side with a probe. If there is any movement, the reluctor wheel retaining bolts are loose. Inspect the engine coolant temperature (ECT) sensor. Use the scan tool in order to compare the ECT with the ambient air temperature on a cold engine. If the coolant temperature reading is more than 5 degrees more or less than the ambient air temperature on a cold engine, inspect for a high resistance in the coolant sensor circuit or the sensor itself. Inspect for an intermittent FRP sensor signal by wiggling the harness between the sensor and the ECM with the ignition ON and the engine OFF, while monitoring the parameter with a scan tool. Inspect for an intermittent crankshaft position (CKP) sensor signal. Refer to «Testing for Intermittent Conditions and Poor Connections»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-service-troubleshooting-diagnosis__testing-for-intermittent-conditions-and-poor) . The Air Induction System for the following: Leaks in the Induction system before the Turbocharger. Refer to Induction System Smoke Test in «Charge Air Cooler Diagnosis (Induction System Smoke Test)»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/testing-diagnostics/#engine-controls-and-fuel-66l-troubleshooting-diagnosis) , «Charge Air Cooler Diagnosis (Full System Air Leak Test)»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/testing-diagnostics/#engine-controls-and-fuel-66l-troubleshooting-diagnosis) or «Charge Air Cooler Diagnosis (Charge Air Cooler Air Leak Test)»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/testing-diagnostics/#engine-controls-and-fuel-66l-troubleshooting-diagnosis) . Leaks in the Charge Air Cooler system. Refer to Charge Air Cooler Air Leak Test in «Charge Air Cooler Diagnosis (Induction System Smoke Test)»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/testing-diagnostics/#engine-controls-and-fuel-66l-troubleshooting-diagnosis) , «Charge Air Cooler Diagnosis (Full System Air Leak Test)»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/testing-diagnostics/#engine-controls-and-fuel-66l-troubleshooting-diagnosis) or «Charge Air Cooler Diagnosis (Charge Air Cooler Air Leak Test)»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/testing-diagnostics/#engine-controls-and-fuel-66l-troubleshooting-diagnosis) . Leaks in the engine assembly. Refer to Full System Air Leak Test in «Charge Air Cooler Diagnosis (Induction System Smoke Test)»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/testing-diagnostics/#engine-controls-and-fuel-66l-troubleshooting-diagnosis) , «Charge Air Cooler Diagnosis (Full System Air Leak Test)»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/testing-diagnostics/#engine-controls-and-fuel-66l-troubleshooting-diagnosis) or «Charge Air Cooler Diagnosis (Charge Air Cooler Air Leak Test)»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/testing-diagnostics/#engine-controls-and-fuel-66l-troubleshooting-diagnosis) . The Fuel System for the following: Inspect the fuel quality. Refer to «Contaminants-in-Fuel Diagnosis»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/testing-diagnostics/#engine-controls-and-fuel-66l-troubleshooting-diagnosis__contaminants-in-fuel-diagnosis) and «Fuel System Specifications»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/testing-diagnostics/#engine-controls-and-fuel-66l-introduction-1-of-2) . Inspect the fuel pressure regulator voltage supply circuit for an intermittent short to ground. Observe the FRP regulator command percent while cranking. A range of 85-95 percent indicates a possible short to ground condition. Inspect the fuel pressure regulator voltage supply circuit for a short to voltage. Inspect the fuel supply to the fuel injection pump. Refer to «Fuel System Diagnosis»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/testing-diagnostics/#engine-controls-and-fuel-66l-troubleshooting-diagnosis) . Inspect the fuel system for a plugged fuel filter, high vacuum, air in the fuel system, etc. Refer to «Fuel System Diagnosis»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/testing-diagnostics/#engine-controls-and-fuel-66l-troubleshooting-diagnosis) . Inspect for air in the fuel system. Refer to «Fuel System Diagnosis»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/testing-diagnostics/#engine-controls-and-fuel-66l-troubleshooting-diagnosis) . Inspect for external fuel leaks. Refer to «Fuel Leak Diagnosis»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/testing-diagnostics/#engine-controls-and-fuel-66l-troubleshooting-diagnosis__fuel-leak-diagnosis) . Inspect for low fuel pressure. Command the fuel pressure to 180 MPa with a scan tool while the engine is at idle. If 180 MPa is not achieved, perform «Fuel System Diagnosis - High Pressure Side»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/testing-diagnostics/#engine-controls-and-fuel-66l-troubleshooting-diagnosis) . Inspect the fuel supply system vacuum while the problem exists. Refer to «Fuel System Diagnosis»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/testing-diagnostics/#engine-controls-and-fuel-66l-troubleshooting-diagnosis) . Inspect the engine speed signal circuit for high resistance. If the ECM or a fuel injector has recently been replaced, it may be necessary to confirm the fuel injector flow rate values. Refer to «Fuel Injector Flow Rate Programming»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/testing-diagnostics/#engine-controls-and-fuel-66l-introduction-1-of-2) . Inspect for restricted or plugged fuel injectors. Refer to «Fuel Injector Balance Test with Tech 2»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/testing-diagnostics/#engine-controls-and-fuel-66l-troubleshooting-diagnosis) . Inspect for a sticking Fuel Pressure Regulator. The symptom for this condition will be an idle surge of at least 100 RPM. This surge will be from 50 RPM above Desired Idle Speed to 50 RPM below Desired Idle Speed. Refer to «Fuel Pressure Regulator Diagnosis»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/testing-diagnostics/#engine-controls-and-fuel-66l-troubleshooting-diagnosis__fuel-pressure-regulator-diagnosis) . Inspect the fuel tank cap vent for proper operation. Engine mechanical for the following. Improper valve timing Bent pushrods Worn rocker arms-Refer to «Valve Rocker Arm and Shaft Cleaning and Inspection»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/mechanical/#engine-mechanical-66l-4-of-5__valve-rocker-arm-and-shaft-cleaning) . Low engine compression-Refer to «Engine Compression Test»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/mechanical/#engine-mechanical-66l-1-of-5__engine-compression-test) . Broken or weak valve springs Worn camshaft lobes-Refer to «Camshaft and Bearings Cleaning and Inspection»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/mechanical/#engine-mechanical-66l-3-of-5) . Excessive oil in the combustion chamber-Leaking valve seals-Refer to «Oil Consumption Diagnosis»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/mechanical/#engine-mechanical-66l-1-of-5__oil-consumption-diagnosis) .
2. If the above conditions do not address the symptom, refer to «Additional Symptoms Tests»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/testing-diagnostics/#engine-controls-and-fuel-66l-troubleshooting-diagnosis) .

Hard Start

1. Verify that the ECT has not shifted in value. Refer to «Temperature Versus Resistance (ECT Sensors)»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/testing-diagnostics/#engine-controls-and-fuel-66l-introduction-1-of-2__temperature-versus-resistance-ect-sensors) or «Temperature Versus Resistance (EGR Temperature Sensors)»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/testing-diagnostics/#engine-controls-and-fuel-66l-introduction-1-of-2__temperature-versus-resistance-egr-temperature-sensors) or «Temperature Versus Resistance (EGT Sensors)»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/testing-diagnostics/#engine-controls-and-fuel-66l-introduction-1-of-2__temperature-versus-resistance-egt-sensors) or «Temperature Versus Resistance (Fuel Temperature Sensor)»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/testing-diagnostics/#engine-controls-and-fuel-66l-introduction-1-of-2__temperature-versus-resistance-fuel-temperature-sensor) or «Temperature Versus Resistance (IAT Sensor 1)»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/testing-diagnostics/#engine-controls-and-fuel-66l-introduction-1-of-2__temperature-versus-resistance-iat-sensor-1) or «Temperature Versus Resistance (IAT Sensor 2)»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/testing-diagnostics/#engine-controls-and-fuel-66l-introduction-1-of-2__temperature-versus-resistance-iat-sensor-2) .
2. Inspect for a slow cranking speed. Refer to «Symptoms - Engine Electrical»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/charging-system/#battery-charging-system-starting-system__symptoms-engine-electrical) .
3. Verify the engine electrical system for correct operation. Refer to «Symptoms - Engine Electrical»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/charging-system/#battery-charging-system-starting-system__symptoms-engine-electrical) .
4. Verify that the driver is using the correct starting procedure as described in the owners manual.
5. Inspect for a restriction in turbocharger inlet duct.
6. Inspect for a restriction or a leak in the intake manifolds.
7. Inspect the exhaust system for a possible restriction. Refer to «Restricted Exhaust»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/exhaust/#engine-exhaust-system) .
8. Inspect for excessive crankshaft endplay that will cause the CKP sensor reluctor wheel to move out of alignment with the CKP sensor.

Hesitation, Sag, Stumble

1. Test the generator. Refer to «Symptoms - Engine Electrical»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/charging-system/#battery-charging-system-starting-system__symptoms-engine-electrical) . Repair the charging system if the generator output voltage is less than 9 volts or more than 16 volts.
2. Inspect for excessive crankshaft endplay that will cause the CKP sensor reluctor wheel to move out of alignment with the CKP sensor.

Poor Fuel Economy

1. Suggest to the driver to read the Important Facts on Fuel Economy in the Owner Manual.
2. Confirm proper interpretation of the Average Fuel Economy value on the DIC. The Fuel Economy value should be reset periodically. Particularly if driving patterns, including load, terrain, etc., have changed significantly since the last Fuel Economy Reset.
3. Suggest to the owner to fill the fuel tank and inspect the fuel economy.
4. The following conditions can reduce fuel economy: Aftermarket body accessories that can affect wind flow over the vehicle. Including air deflectors, flares, etc. Heavy loads being carried or towed, or the shape of large loads Extended idle time Acceleration rate too much or too often Incorrect tire size or air pressure Improper fuel quality and rating-Refer to «Contaminants-in-Fuel Diagnosis»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/testing-diagnostics/#engine-controls-and-fuel-66l-troubleshooting-diagnosis__contaminants-in-fuel-diagnosis) and «Fuel System Specifications»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/testing-diagnostics/#engine-controls-and-fuel-66l-introduction-1-of-2) . Aftermarket ECM calibrations Certain aftermarket air filters or air induction systems An air leak in the induction or engine systems-Refer to full system air leak test in «Charge Air Cooler Diagnosis (Induction System Smoke Test)»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/testing-diagnostics/#engine-controls-and-fuel-66l-troubleshooting-diagnosis) or «Charge Air Cooler Diagnosis (Full System Air Leak Test)»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/testing-diagnostics/#engine-controls-and-fuel-66l-troubleshooting-diagnosis) or «Charge Air Cooler Diagnosis (Charge Air Cooler Air Leak Test)»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/testing-diagnostics/#engine-controls-and-fuel-66l-troubleshooting-diagnosis) . Fuel system issues-Inspect the injector balance rates. Balance rates should be between +4 mm 3 and -6.9 mm 3 in Park or Neutral. Brake system drag Air conditioning system improper operation Incorrect operation of the speedometer

Lack of Power, Hesitation, or Cut Out

1. Inspect the engine electrical system for correct operation. Refer to «Symptoms - Engine Electrical»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/charging-system/#battery-charging-system-starting-system__symptoms-engine-electrical) .
2. Inspect for auxiliary fuel filters. Refer to «Fuel Injection Line Routing Diagram»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/testing-diagnostics/#engine-controls-and-fuel-66l-introduction-1-of-2) for proper fuel filter locations. Aftermarket fuel filters may restrict fuel flow.
3. Compare the vehicle with a similar unit. Ensure the vehicle has an actual problem.
4. Inspect for a proper transmission operation.
5. Inspect the engine oil level and quality.
6. Inspect for an air leak in the charge air cooler. Refer to «Charge Air Cooler Diagnosis (Induction System Smoke Test)»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/testing-diagnostics/#engine-controls-and-fuel-66l-troubleshooting-diagnosis) or «Charge Air Cooler Diagnosis (Full System Air Leak Test)»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/testing-diagnostics/#engine-controls-and-fuel-66l-troubleshooting-diagnosis) or «Charge Air Cooler Diagnosis (Charge Air Cooler Air Leak Test)»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/testing-diagnostics/#engine-controls-and-fuel-66l-troubleshooting-diagnosis) .
7. Inspect for a worn or damaged turbo charger turbine wheel, shaft or compressor wheel.
8. Inspect for a restriction in the charge air cooler.
9. Inspect for a skewed mass air flow (MAF) sensor. Refer to Diagnostic Aids in «DTC P0101»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/testing-diagnostics/#engine-controls-and-fuel-66l-dtc-p0016-to-dtc-p02e7) .
10. Inspect that the exhaust gas recirculation (EGR) valve is fully closing. Remove the EGR valve and visually inspect that there is no light seen between the valves and the valve seats.
11. Ensure that the EGR valve does not bind when manually moving the valve.
12. Inspect the torque converter clutch (TCC) operation.
13. Inspect the air conditioning system for proper operation. Refer to «Air Conditioning (A/C) System Performance Test (Diesel Engine)»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/automatic-hvac-system/#heating-ventilation-and-air-conditioning__air-conditioning-ac-system-performance-test) or «Air Conditioning (A/C) System Performance Test (Gas Engine w/Electric Cooling Fan)»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/automatic-hvac-system/#heating-ventilation-and-air-conditioning__air-conditioning-ac-system-performance-test) or «Air Conditioning (A/C) System Performance Test (Gas Engine w/Engine Driven Fan)»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/automatic-hvac-system/#heating-ventilation-and-air-conditioning__air-conditioning-ac-system-performance-test) or «Air Conditioning (A/C) System Performance Test (HP2 )»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/automatic-hvac-system/#heating-ventilation-and-air-conditioning) .
14. Inspect the exhaust system for a possible restriction.

Rough, Unstable, or Incorrect Idle and Stalling

1. Inspect the engine mounts. Refer to «Engine Mount Inspection»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/mechanical/#engine-mechanical-66l-2-of-5__engine-mount-inspection) .
2. Inspect the intake and exhaust manifolds for casting flash.
3. The exhaust system for damaged or collapsed pipes
4. The exhaust manifold for a collapsed inner wall
5. The mufflers for heat distress or possible internal failure
6. EMI on the reference circuit can cause an engine miss condition. A scan tool can usually detect EMI by monitoring the engine RPM. A sudden increase in RPM, with little change in actual engine RPM change, indicates that EMI is present. If a problem exists, inspect routing of high voltage components, such as fuel injector wiring, near the sensor circuits.
7. Inspect the park neutral position (PNP) switch circuit.

Surges/Chuggles

1. Ensure the driver understands the torque converter clutch (TCC) operation.
2. Ensure the driver understands the A/C compressor operation.
3. Use the scan tool to ensure the vehicle speed sensor (VSS) reading matches the speedometer. This excludes vehicles with electronic transmissions where some variation between VSS and the speedometer is normal.

Fuel Knock/Combustion Noise

1. Inspect for obvious overheating problems. Refer to «Engine Overheating»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/cooling-system-mechanical/#engine-cooling-system__engine-overheating) .
2. Inspect for a low engine coolant level.
3. Inspect for any restricted air flow through the radiator. Refer to «Radiator Cleaning»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/cooling-system-mechanical/#engine-cooling-system__radiator-cleaning) .
4. Inspect for a malfunctioning or incorrect thermostat.
5. Inspect for a correct coolant solution. The solution should be a 50/50 mix of anti-freeze and water.

Excessive Smoke (Black)

1. The DPF is damaged and must be replaced. Inspect the following possible causes that may have damaged the DPF.
2. Inspect for an air leak in the charge air cooler or the air ducts between the turbocharger and the intake manifold. Refer to «Charge Air Cooler Diagnosis (Induction System Smoke Test)»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/testing-diagnostics/#engine-controls-and-fuel-66l-troubleshooting-diagnosis) or «Charge Air Cooler Diagnosis (Full System Air Leak Test)»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/testing-diagnostics/#engine-controls-and-fuel-66l-troubleshooting-diagnosis) or «Charge Air Cooler Diagnosis (Charge Air Cooler Air Leak Test)»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/testing-diagnostics/#engine-controls-and-fuel-66l-troubleshooting-diagnosis) .
3. Inspect for a restriction in the turbocharger charge air cooler.
4. Inspect for a restriction in the intake manifold.
5. Inspect for excessive oil entering the combustion chamber. Refer to «Oil Consumption Diagnosis»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/mechanical/#engine-mechanical-66l-1-of-5__oil-consumption-diagnosis) .
6. Inspect for a stuck open EGR valve.
7. Remove the air inlet tube to the intake manifold. Refer to «Exhaust Gas Recirculation Valve Cooler Replacement»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/testing-diagnostics/#engine-controls-and-fuel-66l-introduction-1-of-2) . Perform steps 1-15.
8. Visually inspect the EGR valve and verify the valve is in the closed position.
9. Ensure that the EGR valve does not bind when manually moving the valve.

Excessive Smoke (White)

1. Check the coolant level in the reservoir. White coolant smoke may be mistaken for blue/gray smoke. If the coolant level is low, refer to «Loss of Coolant»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/cooling-system-mechanical/#engine-cooling-system__loss-of-coolant) .
2. If excessive smoke is present, inspect for a stuck open fuel injector by performing the following procedure: Disconnect the CKP sensor. Remove the glow plugs. Refer to «Glow Plug Replacement - Bank 1»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/testing-diagnostics/#engine-controls-and-fuel-66l-introduction-1-of-2) and «Glow Plug Replacement - Bank 2»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/testing-diagnostics/#engine-controls-and-fuel-66l-introduction-1-of-2) . IMPORTANT: Do not stand in front of the glow plug holes while cranking the engine. Crank the engine while observing the glow plug holes for fuel spray. Replace the fuel injectors for the cylinders that spray fuel. Inspect for contaminated oil or high oil level.
3. If the ECM glow plug control module (GPCM) or a fuel injector has recently been replaced, it may be necessary to confirm the fuel injector flow rate values. Refer to «Fuel Injector Flow Rate Programming»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/testing-diagnostics/#engine-controls-and-fuel-66l-introduction-1-of-2) .
4. Inspect the fuel injectors. Refer to «Fuel Injector Balance Test with Tech 2»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/testing-diagnostics/#engine-controls-and-fuel-66l-troubleshooting-diagnosis) .

Excessive Smoke (Blue, Gray, or White)

Blue, gray, or white smoke during regeneration may indicate a fuel with high sulfur content.

1. Perform the «Diagnostic System Check - Vehicle»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/oem-general-information/#vehicle-diagnostic-information__diagnostic-system-check-vehicle) prior to using this diagnostic procedure.
2. Review «Strategy Based Diagnosis»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/oem-general-information/#vehicle-diagnostic-information__strategy-based-diagnosis) for an overview of the diagnostic approach.
3. «Diagnostic Procedure Instructions»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/oem-general-information/#vehicle-diagnostic-information__diagnostic-procedure-instructions) provides an overview of each diagnostic category.

Circuit/System Description

The malfunction indicator lamp (MIL) is located on the instrument panel cluster (IPC). The MIL informs the driver that an emission system fault has occurred and that the engine control system requires service. The engine control module (ECM) monitors the MIL control circuit for conditions that are incorrect for the commanded states of the MIL. For example, a failure condition exists if the ECM detects low voltage when the MIL is commanded OFF, or high voltage when the MIL is commanded ON.

Diagnostic Aids

An intermittent or poor connection at the MIL control circuit at the inline harness connector may cause this DTC to set. Inspect the connector terminals for any condition that may result in excessive resistance. Refer to Testing for Intermittent Conditions and Poor Connections .

Reference Information

Schematic Reference

1. «Engine Controls Schematics»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/testing-diagnostics/#engine-controls-and-fuel-66l-introduction-1-of-2)
2. «Instrument Cluster Schematics»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/gauges-instrument-panels/#instrument-panel-system-displays-gages)

Connector End View Reference

Component Connector End Views

Electrical Information Reference

1. «Circuit Testing»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-service-troubleshooting-diagnosis__circuit-testing)
2. «Connector Repairs»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-service-troubleshooting-diagnosis__connector-repairs)
3. «Testing for Intermittent Conditions and Poor Connections»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-service-troubleshooting-diagnosis__testing-for-intermittent-conditions-and-poor)
4. «Wiring Repairs»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-service-troubleshooting-diagnosis__wiring-repairs)

DTC Type Reference

Powertrain Diagnostic Trouble Code (DTC) Type Definitions

Scan Tool Reference

Control Module References for scan tool information

Circuit/System Verification

Ignition ON, command the MIL ON and OFF with a scan tool. The MIL should turn ON and OFF with each command.

Circuit/System Testing

1. Ignition ON, verify that the IPC warning indicators are illuminated. If the IPC warning indicators are not illuminated, test the IPC ignition circuit for a short to ground or an open/high resistance. If the circuit tests normal and the ignition circuit fuse is open, replace the IPC.
2. Ignition OFF, disconnect the ECM X2 harness connector. Ignition ON, the MIL should not illuminate. If the MIL is illuminated, test the MIL control circuit terminal X2-30 for a short to ground. If the circuit tests normal, replace the IPC.
3. Ignition ON, connect a 3A fused jumper wire between the MIL control circuit terminal X2-30 and ground. The MIL should illuminate. If the MIL does not illuminate, test the MIL control circuit for a short to voltage, or an open/high resistance. If the circuit tests normal, replace the IPC/bulb.
4. If all circuits/connectors test normal, replace the ECM.

Repair Procedures

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

1. «Instrument Cluster Replacement (Without RPO SLT)»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/gauges-instrument-panels/#instrument-panel-system-displays-gages) or «Instrument Cluster Replacement (With RPO SLT)»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/gauges-instrument-panels/#instrument-panel-system-displays-gages)
2. «Control Module References»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/communication-devices/#programming-and-setup-all-systems__control-module-references) for ECM and ICM replacement, setup, and programming

1. Perform the «Diagnostic System Check - Vehicle»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/oem-general-information/#vehicle-diagnostic-information__diagnostic-system-check-vehicle) prior to using this diagnostic procedure.
2. Review «Strategy Based Diagnosis»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/oem-general-information/#vehicle-diagnostic-information__strategy-based-diagnosis) for an overview of the diagnostic approach.
3. «Diagnostic Procedure Instructions»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/oem-general-information/#vehicle-diagnostic-information__diagnostic-procedure-instructions) provides an overview of each diagnostic category.

The Engine Cranks but Does Not Run diagnostic table is an organized approach to identifying a condition that causes an engine not to start. The Engine Cranks but Does Not Run diagnostic table directs the service technician to the appropriate system diagnosis.

If the cause of an engine cranks but will not run condition has not been found, inspect for the following conditions

1. Hard starting only in cold ambient temperatures. These may cause an intermittent condition that may not occur in the service bay: Fuel heater inoperative-Refer to «Fuel Heater Inoperative»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/testing-diagnostics/#engine-controls-and-fuel-66l-troubleshooting-diagnosis) . Ice blockage at the fuel pickup in the fuel tank-This will be a high vacuum in the supply lines while cranking, and the problem will disappear after the vehicle is brought in the service bay. It may also exhibit a start and stall condition or a starting condition with no acceleration.
2. The correct cranking speed is 100 RPM cold and 180 RPM hot.
3. A basic engine problem
4. Low engine coolant may cause the engine to shut down.

Schematic Reference

Engine Controls Schematics

Connector End View Reference

Component Connector End Views

Electrical Information Reference

1. «Circuit Testing»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-service-troubleshooting-diagnosis__circuit-testing)
2. «Connector Repairs»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-service-troubleshooting-diagnosis__connector-repairs)
3. «Testing for Intermittent Conditions and Poor Connections»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-service-troubleshooting-diagnosis__testing-for-intermittent-conditions-and-poor)
4. «Wiring Repairs»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-service-troubleshooting-diagnosis__wiring-repairs)

Scan Tool Reference

Control Module References for scan tool information

Special Tools

CH-48027 Vacuum Gage

1. If DTCs P0090, P0191, P0193, P0335, P0336, P0340, P0602, P0603, P0604, P0606, P0642, P0643, P064C, P0698, P0699, P2510 are set diagnose those DTCs first.
2. The engine starts and runs. If the engine does not start and run perform the Circuit/System Testing.

1. Inspect for the following conditions: Inadequate fuel in the fuel tanks. Fuel smell or leak-Refer to «Fuel Leak Diagnosis»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/testing-diagnostics/#engine-controls-and-fuel-66l-troubleshooting-diagnosis__fuel-leak-diagnosis) . A plugged air filter collapsed air intake duct A restricted exhaust system-Refer to «Symptoms - Engine Exhaust»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/exhaust/#engine-exhaust-system__symptoms-engine-exhaust) . Contaminants in fuel-Refer to «Contaminants-in-Fuel Diagnosis»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/testing-diagnostics/#engine-controls-and-fuel-66l-troubleshooting-diagnosis__contaminants-in-fuel-diagnosis) .
2. Install the CH-48027 to the fuel rail service port and crank the engine. If more than 5 inches Hg of vacuum was present during cranking, replace the fuel filter and inspect the fuel system restrictions. If less than 1 inches Hg of vacuum was present during cranking, go to «Fuel System Diagnosis»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/testing-diagnostics/#engine-controls-and-fuel-66l-troubleshooting-diagnosis) .
3. Perform the Engine Compression Test. Refer to «Engine Compression Test»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/mechanical/#engine-mechanical-66l-1-of-5__engine-compression-test) . IMPORTANT: During the replacement of the injectors, inspect the inlet and outlet fittings for corrosion or contamination. Refer to «Contaminants-in-Fuel Diagnosis»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/testing-diagnostics/#engine-controls-and-fuel-66l-troubleshooting-diagnosis__contaminants-in-fuel-diagnosis) . If any fuel vapor was emitted during the engine compression test, replace the affected fuel injector.
4. Assemble all disconnected components. Prime the fuel system to at least 10 psi. Attempt to start the engine. If the engine does start, refer to «Fuel System Diagnosis»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/testing-diagnostics/#engine-controls-and-fuel-66l-troubleshooting-diagnosis) . If the engine does not start, refer to «Fuel System Diagnosis - High Pressure Side»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/testing-diagnostics/#engine-controls-and-fuel-66l-troubleshooting-diagnosis) .

Fuel Injector Replacement (Right) or Fuel Injector Replacement (Left)

Repair Verification

The engine starts and runs.

Fuel Pressure Regulator Diagnosis

The Fuel Pressure Regulator graphing procedure offers valuable information on regulator performance by comparing desired and actual fuel rail pressure. An almost perfect comparison between fuel rail pressure and desired fuel rail pressure is found on a fairly new, low mileage engine. A minor ripple is acceptable behavior for the fuel rail pressure regulator and is seen on high mileage engines. A "shark tooth" fluctuation in fuel rail pressure indicates a sticking fuel pressure regulator.

1. Set up the following Min/Max ranges for graphing the fuel rail pressure on the scan tool. Engine Speed Min/Max range is 0-1,000 RPM. Fuel Rail Pressure Min/Max range is 1-160 MPa. Desired Fuel Rail Pressure Min/Max is 1-160 MPa.
2. Start and idle the engine.
3. Observe the live plot for sharp changes or shark tooth pattern in the Fuel Rail Pressure while performing the following actions: Idling the engine Shifting the transmission from Park to Drive and back to Park Turning the steering from left stop position to right stop position Turning the air conditioning ON and OFF
4. If there is a violent fluctuation in the Fuel Rail Pressure, as seen in the surging graph below, replace the fuel pressure regulator. Refer to «Fuel Pressure Regulator Replacement»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/testing-diagnostics/#engine-controls-and-fuel-66l-introduction-1-of-2) .

Scheme 117

Scheme 118

Scheme 119

1. Perform the «Diagnostic System Check - Vehicle»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/oem-general-information/#vehicle-diagnostic-information__diagnostic-system-check-vehicle) prior to using this diagnostic procedure.
2. Review «Strategy Based Diagnosis»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/oem-general-information/#vehicle-diagnostic-information__strategy-based-diagnosis) for an overview of the diagnostic approach.
3. «Diagnostic Procedure Instructions»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/oem-general-information/#vehicle-diagnostic-information__diagnostic-procedure-instructions) provides an overview of each diagnostic category.

Fuel is drawn by the fuel injection pump from the tank to the engine through the fuel supply lines. Fuel flows to the fuel filter/heater element housing, which combines a water separator, a prime pump, fuel heater element and a filter element. A mechanical fuel injection pump at the front of the engine valley includes the fuel supply pump and the high-pressure pump. The small section of the fuel pump assembly is the supply pump, which creates a vacuum to pull fuel from the fuel tank to the high-pressure pump. The vacuum varies with engine load and speed as indicated by the table below. The pump is engine-driven by the camshaft gear. From the high-pressure pump, the pressurized fuel flows to the left fuel rail. A balance pipe from the center of the left rail then feeds the right fuel rail. Each fuel rail supplies one bank of 4 fuel injectors. The fuel rail pressure sensor is mounted in the end of the right fuel rail. Fuel is used to cool and lubricate the fuel injectors and fuel injection pump. The fuel return system is designed to return this fuel to the fuel tank. If the high side fuel pressure becomes excessive, the fuel rail pressure relief valve releases the fuel into the fuel return system. The return fuel travels through the fuel cooler and then to the fuel tank.

Typical Supply Side Vacuum

An Engine Cranks but Will Not Run or Hard Start symptom may exist if air is being drawn into the fuel injection system due to the following conditions

1. Fuel contamination-Refer to «Contaminants-in-Fuel Diagnosis»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/testing-diagnostics/#engine-controls-and-fuel-66l-troubleshooting-diagnosis__contaminants-in-fuel-diagnosis) .
2. Deformed or cut O-rings at the fuel supply line connections
3. Improperly seated fuel supply line fittings
4. Porous or weathered rubber fuel supply lines
5. Fuel filter vent screw not tighten or cross threaded
6. Fuel filter not tighten properly

Special Tools

1. J 23738-A MityVac
2. EN-47969 Fuel Supply Diagnostic Hose. See «Special Tools»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/testing-diagnostics/#engine-controls-and-fuel-66l-introduction-1-of-2) .
3. CH-48027 Digital Pressure Gage
4. J 44581 Fuel Line Disconnect Tool. See «Special Tools»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/testing-diagnostics/#engine-controls-and-fuel-66l-introduction-1-of-2) .

Observe the Actual Fuel Rail Pressure parameter with a scan tool. During engine cranking, the pressure should be at least 10 MPa. With the engine running at idle the pressure should be close to the Desired Fuel Rail Pressure. As the engine speed increase, the Desired Fuel Rail Pressure and the Actual Fuel Rail Pressure should be within 2 MPa of each other.

1. Install the CH-48027 to the fuel system service port on the right front side of the engine.
2. Prime the fuel system until 10 psi is indicated on the CH-48027 . Fuel pressure should not drop below 2 psi in less than one minute. If fuel pressure drops below 2 psi in less than one minute, go to step 4.
3. Attempt to start and idle the engine. Observe the CH-48027 during idle. The vacuum should be between 1-3 in Hg. If more than 3 in Hg is observed at idle, visually inspect the following items: Fuel filter element for a restriction Hoses and lines that are flattening when the engine is running, or have kinks that would restrict the flow of fuel If engine did not start and no vacuum was observed, refer to «Fuel Injection Pump Replacement»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/testing-diagnostics/#engine-controls-and-fuel-66l-introduction-1-of-2) .
4. Disconnect the fuel supply line at the engine and install a J 23738-A using the J 44581 . See «Special Tools»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/testing-diagnostics/#engine-controls-and-fuel-66l-introduction-1-of-2) .
5. Apply vacuum to the fuel supply pipe until 25 in Hg has been reached. Wait for at least one minute to allow the fuel system to stabilize. Vacuum should not drop below 8 in Hg within 10 minutes. If vacuum cannot be obtained or the vacuum drops below 8 in Hg within 10 minutes, repair the air leak at fuel filter/heater element housing connections or at the fuel hoses/pipes on the engine supply line.
6. Remove both hoses from the fuel filter/heater element housing assembly. Cap the suction side port of the fuel filter/heater element housing assembly. Apply 25 in Hg to the discharge port of the fuel filter/heater element housing assembly. Vacuum should not drop below 8 in Hg within 10 minutes. If vacuum drops below 8 in Hg within 10 minutes, replace the fuel filter/heater element housing assembly. IMPORTANT: The engine may start and then stall after briefly running.
7. Remove the J 23738-A from the fuel filter/heater element housing assembly. Install the removed fuel filter/heater element housing assembly, and cap off the fuel supply pipe on the engine. Crank the engine in 15-second intervals while observing the CH-48027 . More than 5 in Hg vacuum should be observed during cranking. If less than 5 in Hg was observed on the vacuum gage during cranking, replace the fuel injection pump.
8. Install the fuel supply line at the engine, and disconnect the chassis fuel supply line at the fuel tank. Install a J 23738-A to the supply hose at the fuel tank using the J 44581 . See «Special Tools»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/testing-diagnostics/#engine-controls-and-fuel-66l-introduction-1-of-2) .
9. Apply vacuum to the supply hose at the fuel tank until 25 in Hg has been reached. Wait for a least one minute for the fuel system to stabilize. Vacuum should not drop below 8 in Hg within 10 minutes. If vacuum cannot be obtained, or the vacuum drops below 8 in Hg within 10 minutes, repair the air leak in the fuel supply line between the engine and fuel tank, or the connection of the supply line to the engine.
10. Install all components and lines that were previously removed or disconnected.
11. Install the EN-47969 on the fuel supply line at the engine. See «Special Tools»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/testing-diagnostics/#engine-controls-and-fuel-66l-introduction-1-of-2) . Create a vertical loop in the hose to observe the incoming fuel for air bubbles.
12. Open the bleed screw on top of the fuel filter/heater element housing. Prime the system until fuel appears at the bleed screw. Continue to prime the fuel system until the engine starts and runs.
13. Run the engine for at least 10 minutes to allow the fuel system to stabilize, and purge any air from the system.
14. At a stabilized idle, observe the fuel entering the EN-47969 for air bubbles. See «Special Tools»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/testing-diagnostics/#engine-controls-and-fuel-66l-introduction-1-of-2) . If air bubbles were observed entering the transparent hose, test the fuel sender for leaks. Refer to «Fuel Sender Assembly Replacement»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/testing-diagnostics/#engine-controls-and-fuel-66l-introduction-1-of-2) .
15. Install the fuel sender, fuel tank, and all fuel system connections and components that were previously disconnected. Leave the EN-47969 connected to the fuel supply line. See «Special Tools»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/testing-diagnostics/#engine-controls-and-fuel-66l-introduction-1-of-2) . Prime the fuel system 30 times to remove the air from the fuel hoses. Continue to prime the fuel system until the engine starts and runs. Observe the fuel entering the transparent hose. If air bubbles are still present, refer to Diagnostic Aids. If no air bubbles are present, remove the EN-47969 and run the engine to ensure no fuel leaks exist. See «Special Tools»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/testing-diagnostics/#engine-controls-and-fuel-66l-introduction-1-of-2) .

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

1. «Fuel Injection Pump Replacement»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/testing-diagnostics/#engine-controls-and-fuel-66l-introduction-1-of-2)
2. «Fuel Sender Assembly Replacement»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/testing-diagnostics/#engine-controls-and-fuel-66l-introduction-1-of-2)

1. Perform the «Diagnostic System Check - Vehicle»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/oem-general-information/#vehicle-diagnostic-information__diagnostic-system-check-vehicle) prior to using this diagnostic procedure.
2. Review «Strategy Based Diagnosis»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/oem-general-information/#vehicle-diagnostic-information__strategy-based-diagnosis) for an overview of the diagnostic approach.
3. «Diagnostic Procedure Instructions»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/oem-general-information/#vehicle-diagnostic-information__diagnostic-procedure-instructions) provides an overview of each diagnostic category.

Fuel is used to cool and lubricate the fuel injectors and the fuel injection pump. The fuel return system is designed to return this fuel to the fuel tank. If the high side fuel pressure becomes excessive, the fuel rail pressure relief valve releases the fuel into the fuel return system. The return fuel travels through the fuel cooler to the fuel tank.

Bent or pinched fuel return lines may cause an external fuel leak or engine performance concerns.

Special Tools

J 44581 Fuel Line Disconnect Tool. See Special Tools .

Inspect the fuel return hoses and lines on the engine and chassis for any external fuel leaks.

1. Disconnect the fuel return line at the engine. Refer to «Metal Collar Quick Connect Fitting Service»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/testing-diagnostics/#engine-controls-and-fuel-66l-introduction-1-of-2) .
2. Remove the fuel filler cap.
3. Apply 6.9 kPa (1 psi) of pressure air into the fuel return at the engine. Air flow should be detected at fuel filler tube.
4. If air flow was not detected at the fuel filler tube, disconnect the fuel return line at the fuel sender and apply 6.9 kPa (1 psi) of air pressure into the fuel return line at the engine. If air flow was present, replace the fuel sender assembly. If no air flow was present, inspect for a restricted or a damaged fuel return line. Repair or replace the fuel return line.

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

1. «Fuel Feed Pipe Replacement»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/testing-diagnostics/#engine-controls-and-fuel-66l-introduction-1-of-2)
2. «Fuel Sender Assembly Replacement»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/testing-diagnostics/#engine-controls-and-fuel-66l-introduction-1-of-2)

Fuel Leak Diagnosis

1. Remove the air cleaner assemble. Refer to «Air Cleaner Assembly Replacement»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/testing-diagnostics/#engine-controls-and-fuel-66l-introduction-1-of-2) .
2. Clean all of the fuel lines between the fuel injection pump and the fuel injectors using brake cleaning solvent, and let dry.
3. Add 8 ounces of oil dye to the fuel tank. On dual tanks, add the dye to the front, or primary tank. Refer to «Fuel System Description»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/testing-diagnostics/#engine-controls-and-fuel-66l-introduction-1-of-2__fuel-system-description) .
4. Start and idle the engine for 3-5 minutes.
5. Command the fuel pressure control to 160 MPa (23,206 psi) with a scan tool.
6. Inspect for fuel leaks around the fuel injection pump, fuel rails, and fuel injector supply lines with a J 28428-E High Intensity Black Light Kit. See «Special Tools»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/testing-diagnostics/#engine-controls-and-fuel-66l-introduction-1-of-2) . Tighten or replace any leaking lines or components. Refer to the following: «Fastener Tightening Specifications»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/testing-diagnostics/#engine-controls-and-fuel-66l-introduction-1-of-2__fastener-tightening-specifications) «Fuel Injection Line Routing Diagram»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/testing-diagnostics/#engine-controls-and-fuel-66l-introduction-1-of-2) «Fuel Injection Fuel Return Pipe Replacement - Left Side»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/testing-diagnostics/#engine-controls-and-fuel-66l-introduction-1-of-2) «Fuel Injection Fuel Return Pipe Replacement - Right Side»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/testing-diagnostics/#engine-controls-and-fuel-66l-introduction-1-of-2) «Fuel Feed Pipe Replacement»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/testing-diagnostics/#engine-controls-and-fuel-66l-introduction-1-of-2) «Fuel Injection Fuel Rail Assembly Replacement - Bank 1»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/testing-diagnostics/#engine-controls-and-fuel-66l-introduction-1-of-2) «Fuel Injection Fuel Rail Assembly Replacement - Bank 2»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/testing-diagnostics/#engine-controls-and-fuel-66l-introduction-1-of-2) «Fuel Injection Pump Replacement»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/testing-diagnostics/#engine-controls-and-fuel-66l-introduction-1-of-2) «Fuel Injector Replacement (Right)»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/testing-diagnostics/#engine-controls-and-fuel-66l-introduction-1-of-2) «Fuel Injector Replacement (Left)»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/testing-diagnostics/#engine-controls-and-fuel-66l-introduction-1-of-2)
7. A fuel leak may be caused by restricted return fuel lines. Refer to «Fuel Return System Diagnosis»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/testing-diagnostics/#engine-controls-and-fuel-66l-troubleshooting-diagnosis) .

1. Perform the «Diagnostic System Check - Vehicle»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/oem-general-information/#vehicle-diagnostic-information__diagnostic-system-check-vehicle) prior to using this diagnostic procedure.
2. Review «Strategy Based Diagnosis»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/oem-general-information/#vehicle-diagnostic-information__strategy-based-diagnosis) for an overview of the diagnostic approach.
3. «Diagnostic Procedure Instructions»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/oem-general-information/#vehicle-diagnostic-information__diagnostic-procedure-instructions) provides an overview of each diagnostic category.

High Pressure System

The fuel injection pump at the front of the engine valley includes a fuel supply pump and a high-pressure pump. Fuel is drawn by the fuel supply pump from the primary fuel tank and delivered to the high-pressure pump. The pump is engine-driven by the camshaft gear. High pressure fuel is regulated by the fuel pressure regulator mounted on the fuel injection pump. From the high-pressure pump, the fuel moves to the left and right fuel rails through high pressure metal lines. Each fuel rail distributes high pressure fuel to one bank of 4 fuel injectors. The fuel pressure relief valve is location on the left rail, and relieves excessive fuel pressure which returns to the fuel tank.

Return System

The fuel return system routes fuel from the fuel injectors, the pressure relief valve, and the fuel injection pump. The return fuel travels to the fuel cooler and then to the fuel tank. This fuel is used to cool and lubricate the injection pump and the injectors.

1. The fuel return volumes vary based on the American Petroleum Institute (API) rating of the diesel fuel.
2. A fuel injector may have high fuel return flow only at higher engine temperatures.

Special Tools

1. J 45873 Fuel Return Volume Test Kit. See «Special Tools»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/testing-diagnostics/#engine-controls-and-fuel-66l-introduction-1-of-2) .
2. J-45873-30 Injector Flow Test Adapter. See «Special Tools»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/testing-diagnostics/#engine-controls-and-fuel-66l-introduction-1-of-2) .

With the engine running at idle the Actual Fuel Pressure should be close to the Desired Fuel Rail Pressure. During engine cranking the Actual Fuel Pressure should be at least 10 MPa. Inspect the fuel return hoses and lines for external leaks or damage.

1. Remove the fuel pressure relief valve return hose and plug the hose to prevent fuel leakage.
2. Install a section of rubber fuel hose on the fuel pressure relief valve connection and place loose end of hose into a clean fuel container. IMPORTANT: Fuel that is contaminated with gasoline may cause permanent damage to the fuel pressure relief valve. Refer to «Contaminants-in-Fuel Diagnosis»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/testing-diagnostics/#engine-controls-and-fuel-66l-troubleshooting-diagnosis__contaminants-in-fuel-diagnosis) . If the engine cranks but does not start, crank engine for 15 seconds. Observe for fuel leaking from fuel pressure relief valve. If fuel leaks from the fuel pressure relief valve, replace the pressure relief valve. Refer to «Fuel Pressure Relief Valve Replacement»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/testing-diagnostics/#engine-controls-and-fuel-66l-introduction-1-of-2) . If the engine starts and runs, idle the engine while commanding the fuel rail pressure to 180 MPa with a scan tool. Observe for fuel leaking from fuel pressure relief valve. If fuel leaks from the fuel pressure relief valve, replace the pressure relief valve. Refer to «Fuel Pressure Relief Valve Replacement»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/testing-diagnostics/#engine-controls-and-fuel-66l-introduction-1-of-2) .
3. Remove the fuel return hose from the fuel injectors of the right cylinder bank. Refer to «Fuel Injection Fuel Return Pipe Replacement - Right Side»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/testing-diagnostics/#engine-controls-and-fuel-66l-introduction-1-of-2) .
4. Connect the yellow hoses from the J 45873 to the J-45873-30 . See «Special Tools»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/testing-diagnostics/#engine-controls-and-fuel-66l-introduction-1-of-2) .
5. Connect the J-45873-30 with yellow hoses to each fuel injector return port of the right cylinder bank, and install the retaining clips. See «Special Tools»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/testing-diagnostics/#engine-controls-and-fuel-66l-introduction-1-of-2) .
6. Install the 4 yellow hoses in the J 45873 graduated cylinders in numerical order. See «Special Tools»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/testing-diagnostics/#engine-controls-and-fuel-66l-introduction-1-of-2) .
7. Connect the fuel return hoses to the J-45873-30 to prevent leakage. See «Special Tools»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/testing-diagnostics/#engine-controls-and-fuel-66l-introduction-1-of-2) . If the engine starts and runs, idle the engine until fuel start dripping into all the graduated cylinders and yellow hoses are full of fuel. IMPORTANT: The engine cranking speed must be more than 150 RPM during the cranking portion of this test. If the engine does not start, crank the engine in 15-second intervals, with 1 minute cooling time between intervals, until fuel starts to flow into all of the graduated cylinders.
8. Elevate the 4 yellow hoses to retain the fuel in the hoses, and empty the 4 graduated cylinders into a suitable container.
9. Install the 4 yellow hoses in the J 45873 graduated cylinders in numerical order. See «Special Tools»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/testing-diagnostics/#engine-controls-and-fuel-66l-introduction-1-of-2) . If the engine starts and runs, idle the engine for 15 seconds. If the engine does not start, crank the engine for 15 seconds.
10. Measure the quantity of fuel in each of the graduated cylinders. Refer to «Fuel System Specifications»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/testing-diagnostics/#engine-controls-and-fuel-66l-introduction-1-of-2) for the desired quantities. If high return flows were recorded, replace those fuel injectors that had high return flow and retest the fuel return flow, referring to «Fuel System Specifications»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/testing-diagnostics/#engine-controls-and-fuel-66l-introduction-1-of-2) . Replace any additional high return flow injectors and proceed to the next number step.
11. Install and connect all fuel system components that were previously removed or disconnected.
12. Remove the fuel return pipes from the fuel injectors of the left cylinder bank and repeat the fuel return flow test previously preformed on the right cylinder bank. If high return flows were recorded, replace those fuel injectors that had high return flow and retest the fuel return flow, referring to «Fuel System Specifications»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/testing-diagnostics/#engine-controls-and-fuel-66l-introduction-1-of-2) . Replace any additional high return flow injectors and proceed to the next number step.
13. Install and connect all fuel system components that were previously removed or disconnected.
14. Start and idle the engine. You may have to prime the fuel system before the engine will start. Command the fuel pressure control to 180 MPa with a scan tool. The actual fuel pressure should be the same as the commanded pressure. If the engine does not start or the fuel pressure is less than 145 MPa when commanded, replace the fuel injection pump.
15. Command the fuel pressure control to 180 MPa with a scan tool. The fuel pressure should be able to reach 145 MPa when commanded. If the fuel pressure is less than the specified value, refer to «Fuel System Diagnosis»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/testing-diagnostics/#engine-controls-and-fuel-66l-troubleshooting-diagnosis) .
16. Operate the vehicle in order to verify the repairs.

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

1. «Fuel Injection Pump Replacement»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/testing-diagnostics/#engine-controls-and-fuel-66l-introduction-1-of-2)
2. «Fuel Pressure Relief Valve Replacement»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/testing-diagnostics/#engine-controls-and-fuel-66l-introduction-1-of-2)
3. «Fuel Injector Replacement (Right)»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/testing-diagnostics/#engine-controls-and-fuel-66l-introduction-1-of-2) or «Fuel Injector Replacement (Left)»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/testing-diagnostics/#engine-controls-and-fuel-66l-introduction-1-of-2)

1. Perform the «Diagnostic System Check - Vehicle»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/oem-general-information/#vehicle-diagnostic-information__diagnostic-system-check-vehicle) prior to using this diagnostic procedure.
2. Review «Strategy Based Diagnosis»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/oem-general-information/#vehicle-diagnostic-information__strategy-based-diagnosis) for an overview of the diagnostic approach.
3. «Diagnostic Procedure Instructions»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/oem-general-information/#vehicle-diagnostic-information__diagnostic-procedure-instructions) provides an overview of each diagnostic category.

The fuel injector balance test is performed when a misfire, knock, excessive smoke, or rough running condition exists with no electrical DTCs. This test uses the Balance Rate and Cylinder Power Balance test to identify cylinders that are not producing the designed power output. The balance rate adjustments are utilized by the engine control module (ECM) only at idle. The balance rates are the fuel adjustments for each individual cylinder based on the variations in engine crankshaft speed. The balance rates will change depending on if the transmission is in Neutral or Drive. During the Cylinder Power Balance portion of the test, the ECM turns OFF individual injectors while the engine is running. The ECM adjusts for the drop in engine RPM during cancellation and may not change on the scan tool display. The lack of power at the cancelled cylinder will feel like a misfiring cylinder or vibration. If a fuel injector is turned OFF and there is a no difference felt when compared to the other cylinders, that cylinder is identified with the concern. If the customer concern occurs during idle or during off-idle tip in acceleration, the balance rates are used to identify the cylinder with a fault related to the fuel injector or engine compression.

1. The Cylinder Power Balance Test may be performed at any engine speed or load from idle to wide open throttle (WOT). There is a 5-minute time limit for each test.
2. A high balance rate may be caused by a fuel injector or cylinder compression only if the ECM can control fuel pressure.

1. Start and run the engine until the coolant temperature is more than 82°C (180°F). Turn OFF all accessories.
2. Perform the fuel pressure regulator test, refer to «Fuel Pressure Regulator Diagnosis»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/testing-diagnostics/#engine-controls-and-fuel-66l-troubleshooting-diagnosis__fuel-pressure-regulator-diagnosis) .
3. With a scan tool, command the Balance Rate Monitor ON. Balance rates should be between +4 mm 3 and -6.9 mm 3 in Park or Neutral. Balance rates outside the range may indicate contaminated fuel. Refer to «Contaminants-in-Fuel Diagnosis»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/testing-diagnostics/#engine-controls-and-fuel-66l-troubleshooting-diagnosis__contaminants-in-fuel-diagnosis) .
4. Perform the Cylinder Power Balance Test with a scan tool. During cylinder cancellation a noticeable power difference will feel like a misfiring cylinder or vibration.

Perform the engine compression test. Refer to Engine Compression Test .

1. If the compression indicated any of the cylinders had low compression, refer to «Symptoms - Engine Mechanical»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/mechanical/#engine-mechanical-66l-1-of-5) .
2. If the engine did not have low compression on any of the cylinders, replace the fuel injectors on the cylinders that had low cylinder power contribution, high balance rates, or a noise/smoke change during cancellation.

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

1. «Fuel Injector Replacement (Right)»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/testing-diagnostics/#engine-controls-and-fuel-66l-introduction-1-of-2) or «Fuel Injector Replacement (Left)»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/testing-diagnostics/#engine-controls-and-fuel-66l-introduction-1-of-2)
2. «Fuel Pressure Regulator Replacement»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/testing-diagnostics/#engine-controls-and-fuel-66l-introduction-1-of-2)

Fuel Tank Leak Test

The diagnosis of fuel odor may be a condition of a leaking fuel tank, filler neck or filler cap. A defective filler cap, a plugged or pinched vent pipe can cause a collapsed fuel tank. Loose mounting straps or foreign material in tank may be the cause of a rattle at the fuel tank.

Leak Check Procedure

This check requires the fuel sender and the O-ring to be installed.

1. Disconnect the battery cables.
2. Drain the fuel tank. Refer to «Fuel Tank Draining»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/testing-diagnostics/#engine-controls-and-fuel-66l-introduction-1-of-2) .
3. Remove the fuel tank. Refer to «Fuel Tank Replacement (Pickup)»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/testing-diagnostics/#engine-controls-and-fuel-66l-introduction-1-of-2) or «Fuel Tank Replacement (Cab/Chassis - Front)»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/testing-diagnostics/#engine-controls-and-fuel-66l-introduction-1-of-2) or «Fuel Tank Replacement (Cab/Chassis - Rear)»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/testing-diagnostics/#engine-controls-and-fuel-66l-introduction-1-of-2) .
4. Cap the fuel feed tube and the fuel return tube on the fuel sender.
5. Connect a piece of hose to the filler tube nipple and plug the opposite end.
6. Submerge the tank in water or apply a soap solution to the outside of the tank.
7. Apply 35 kPa (5 psi) of air pressure to the vent hose of the fuel tank. A leak will show up as bubbles.

Contaminants-in-Fuel Diagnosis

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. Service station tanks may contain fungi that could be pumped into a vehicle during refueling.

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 fuel system components including fuel sender assembly, pipes, fuel injectors, and fuel 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 due to possible engine power loss. It is permissible to have biocide in the fuel when starting to tow, but do not add any biocide while towing.

Water in fuel will also create drivability concerns and loss of engine power. If water is present in the fuel system, the fuel cannot cool and lubricate the components, causing overheating, rust and corrosion. This can result in component failure. Water can enter the fuel system in several ways, either through a contaminated refueling source, or through long term condensation the vehicle fuel tanks.

Like fungi and water, gasoline contamination will cause drivability concerns and a possible hard starting or a no start condition if the overall content is large enough. Gasoline raises the API rating and reduces cooling and lubrication, resulting in possible component failure.

Water in fuel will also create drivability concerns and loss of engine power. If water is present in the fuel system, the fuel cannot cool and lubricate the components, causing overheating, rust and corrosion. This can result in component failure. Water can enter the fuel system in several ways, either through a contaminated refueling source, or through long term condensation the vehicle fuel tanks.

Like fungi and water, gasoline contamination will cause drivability concerns and a possible hard starting or a no start condition if the overall content is large enough. Gasoline raises the API rating and reduces cooling and lubrication, resulting in possible component failure.

It is acceptable to use diesel fuel containing up to 5 percent bio-diesel. Bio-diesel is produced from vegetable oils or animal fat that have been chemically modified to reduce the possibility of damage to the fuel system and engine components. Concentrations greater than B5 fuels or the use of unmodified bio-oils blended into diesel fuel at any concentration is not recommended and may cause drivability concerns or component failure.

Inspecting for Fuel Contaminants

1. Test the fuel specific gravity and record the results. Refer to «Fuel System Specifications»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/testing-diagnostics/#engine-controls-and-fuel-66l-introduction-1-of-2) .
2. Remove the fuel filter and inspect the inside area of the fuel filter for dirt, water deposits, or other debris.
3. Drain the fuel filter into an approved clear container and allow the contents to settle. Observe the container for contaminant separation.
4. Remove the water-in-fuel sensor from the bottom of the fuel filter and inspect inside the filter for rust deposits, dirt, or other debris.
5. If contaminants are present in the fuel or in any of the inspected areas, remove the fuel lines to the injectors and inspect the fuel injector return outlets and feed inlets for rust or corrosion.

1. Replace the fuel injectors if rust or corrosion is present. Refer to «Fuel Injector Replacement (Right)»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/testing-diagnostics/#engine-controls-and-fuel-66l-introduction-1-of-2) or «Fuel Injector Replacement (Left)»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/testing-diagnostics/#engine-controls-and-fuel-66l-introduction-1-of-2) and «Fuel System Cleaning»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/testing-diagnostics/#engine-controls-and-fuel-66l-introduction-1-of-2__fuel-system-cleaning) .
2. If rust or corrosion was not present in the injectors, but contaminated fuel was present, refer to «Fuel System Cleaning»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/testing-diagnostics/#engine-controls-and-fuel-66l-introduction-1-of-2__fuel-system-cleaning) and attempt to start and run the engine after procedure is completed.

1. Perform the «Diagnostic System Check - Vehicle»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/oem-general-information/#vehicle-diagnostic-information__diagnostic-system-check-vehicle) prior to using this diagnostic procedure.
2. Review «Strategy Based Diagnosis»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/oem-general-information/#vehicle-diagnostic-information__strategy-based-diagnosis) for an overview of the diagnostic approach.
3. «Diagnostic Procedure Instructions»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/oem-general-information/#vehicle-diagnostic-information__diagnostic-procedure-instructions) provides an overview of each diagnostic category.

The purpose of the Intake Air Leak Smoke Test is to aid in finding an air leak between the mass air flow sensor and turbocharger inlet. This test will also aid in finding air leaks in the crankcase ventilation system.

Special Tools

1. J 41413-200 Evaporative Emission System Tester (EEST)
2. J 41413-SPT High Intensity White Light

Smoke Test Application

1. Ignition OFF, remove the air filter restriction indicator.
2. Connect the J 41413-200 to the vehicle at the air restrictor indicator port.
3. Place the air filter in a disposable plastic bag in the air cleaner housing to help prevent smoke leakage.
4. Apply smoke continuously with the J 41413-200 while moving all duct work, pipes, and tubes.
5. To improve the visibility of the smoke exiting the engine, observe the suspected leak area from different angles.
6. Inspect for smoke at the following locations: Crankcase ventilation hoses and pipes Mass air flow intake air ducts PCV valve and seals Turbocharger inlet and outlet connections Replace the affected gasket, seal, or component as necessary.
7. Retest the engine for air leaks.
8. Remove the disposable bag from the air filter. Install the air filter and air filter restriction indicator.

1. Perform the «Diagnostic System Check - Vehicle»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/oem-general-information/#vehicle-diagnostic-information__diagnostic-system-check-vehicle) prior to using this diagnostic procedure.
2. Review «Strategy Based Diagnosis»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/oem-general-information/#vehicle-diagnostic-information__strategy-based-diagnosis) for an overview of the diagnostic approach.
3. «Diagnostic Procedure Instructions»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/oem-general-information/#vehicle-diagnostic-information__diagnostic-procedure-instructions) provides an overview of each diagnostic category.

Special Tools

1. EN 47603: Compression Gage Adapter
2. J 46091: Charge Air Cooler Tester
3. J 46091-15: Engine Pressure Test Adapter

J 46091-1 Pressure Regulator Adjustment

Note. Some J 46091-1 regulators may have the adjusting knob riveted in place. The rivet head must be drilled out with a 5/16 inch drill bit before adjustment. Do not drill more than 1/8 inch in depth, or just enough to remove the rivet head. The rivet shaft does not have to be removed from the regulator.

1. Connect the EN 47603: Gage Adapter compression adapter to the J 46091: Tester gage set and connect shop air to the J 46091: Tester.
2. Open the shutoff valve, then slowly turn the regulator on the J 46091: Tester clockwise until the gage reads 206 kPa (30 psi).
3. Close the air supply valve and remove the EN 47603: Gage Adapter from the gage assembly.
4. The gage set is now calibrated to perform the test.

Scheme 120

1. Loosen the clamp (1) that fastens the left air cooler duct (4) to the turbocharger.
2. Remove the left charge air cooler inlet duct connector (4) from the turbocharger.
3. Remove both fender wheelhouse liners. Refer to «Front Wheelhouse Liner Replacement - Right Side (Chevrolet)»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/frames-subframes-crossmembers/#frame-and-underbody) or «Front Wheelhouse Liner Replacement - Right Side (GMC)»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/frames-subframes-crossmembers/#frame-and-underbody) and «Front Wheelhouse Liner Replacement - Left Side (Chevrolet)»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/frames-subframes-crossmembers/#frame-and-underbody) or «Front Wheelhouse Liner Replacement - Left Side (GMC)»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/frames-subframes-crossmembers/#frame-and-underbody) .
4. Remove the air cleaner box tray bracket.
5. Use the clamp to attach the J-46091-2 (1) from the J 46091: Tester to the duct connector, and tighten the clamp to 8 N.m (70 lb in).
6. Secure the J 46091: Tester (1) safety cable (2) to a safe location (3).

Turbocharger Exhaust Pipe Connection

1. Raise and support the vehicle. Refer to «Lifting and Jacking the Vehicle»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/hoistjack/#general-information) .
2. Remove the catalytic converter. Refer to «Catalytic Converter Replacement (With LU3)»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/exhaust/#engine-exhaust-system) or «Catalytic Converter Replacement (With V8 Engine)»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/exhaust/#engine-exhaust-system) or «Catalytic Converter Replacement (With LMM)»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/exhaust/#engine-exhaust-system) .
3. Install the J 46091-15: Test Adapter with the exhaust pipe clamp to the turbocharger exhaust pipe using the clamp from the catalytic converter.

Air Pressure Application

1. Attach the gage/regulator assembly from the J 46091: Tester to the quick disconnect fitting on the J-46091-2.
2. Connect the air supply to the air valve on the gage/regulator assembly.
3. Open the air supply valve slowly, increasing the air pressure to a maximum of 206 kPa (30 psi) while listening for abnormal air leaks.
4. Leave the valve ON for the duration of the test.

Leak Test Results

Note. An air leak that appears as small bubbles or foaming is normal. Intake Air Heater gaskets that show a small leak or foaming is normal.

1. With the air valve ON, the gage on the regulator assembly should read greater than 158 kPa (23 psi), and there should be no abnormal air leaks. If the air pressure gage reads less than 158 kPa (23 psi) with constant air pressure applied, and audible air leaks are present, the leak test has failed. Perform the following procedure: Inspect for air leaks by listening for excessive hissing sounds. Inspect for air leaks by using a pump spray bottle to apply a soapy solution, while observing for excessive soapy bubbles at all of the following engine locations: Charge air cooler pipes/hoses connections Charge air cooler core EGR valve gaskets EGR valve cooler gaskets Exhaust manifold gaskets Turbocharger gaskets, inlet and outlet connections Intake manifold gaskets If any abnormal leaks are found, replace the affected gasket or component as necessary.
2. Retest the engine system for air leaks. The gage on the regulator assembly should read greater than 158 kPa (23 psi), and there should be no abnormal air leaks. If the gage reads less than 158 kPa (23 psi) with air valve ON, and audible air leaks are present, recheck for air leaks.
3. If no other air leaks are found, assemble the vehicle. Remove the tester and adapters by performing the following procedure: Slowly bleed the air from the cooler by depressing the relief valve on the adapter. Remove the air hose, gage/regulator assembly, and both adapters. Connect the charge air hose to the turbocharger with the clamp and tighten the clamp to 8 N.m (70 lb in). Install the catalytic converter. Refer to «Catalytic Converter Replacement (With LU3)»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/exhaust/#engine-exhaust-system) or «Catalytic Converter Replacement (With V8 Engine)»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/exhaust/#engine-exhaust-system) or «Catalytic Converter Replacement (With LMM)»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/exhaust/#engine-exhaust-system) . Clear all DTC information with a scan tool.

1. Perform the «Diagnostic System Check - Vehicle»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/oem-general-information/#vehicle-diagnostic-information__diagnostic-system-check-vehicle) prior to using this diagnostic procedure.
2. Review «Strategy Based Diagnosis»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/oem-general-information/#vehicle-diagnostic-information__strategy-based-diagnosis) for an overview of the diagnostic approach.
3. «Diagnostic Procedure Instructions»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/oem-general-information/#vehicle-diagnostic-information__diagnostic-procedure-instructions) provides an overview of each diagnostic category.

Special Tools

1. EN 47603: Compression Gage Adapter
2. J 46091: Charge Air Cooler Tester
3. J 46091-5: Charge Air Cooler Tester Adapter

Note. Some J 46091-1 regulators may have the adjusting knob riveted in place. The rivet head must be drilled out with a 5/16 inch drill bit before adjustment. Do not drill more than 1/8 inch in depth, or just enough to remove the rivet head. The rivet shaft does not have to be removed from the regulator.

1. Connect the EN 47603: Gage Adapter compression adapter to the J 46091: Tester gage set and connect shop air to the J 46091: Tester.
2. Open the shutoff valve, then slowly turn the regulator on the J 46091: Tester clockwise until the gage reads 206 kPa (30 psi).
3. Close the air supply valve and remove the EN 47603: Gage Adapter from the gage assembly.
4. The gage set is now calibrated to perform the test.

Charge Air Cooler Outlet Connection (Engine Air Intake COLD Side)

Note. It is not necessary to remove the charge air cooler from the vehicle to perform this test.

1. Refer to «Intake Air Heater Replacement»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/testing-diagnostics/#engine-controls-and-fuel-66l-introduction-1-of-2) for intake air heater removal.
2. Install the J 46091-5: Charge Air Cooler Tester Adapter plate and gaskets on the inlet tube studs.
3. Install the 2 intake air heater nuts and tighten the nuts to 8 N.m (70 lb in).

Charge Air Cooler Inlet Connection (Engine Air Intake HOT Side)

1. Remove the intake manifold cover. Refer to «Intake Manifold Cover Replacement»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/mechanical/#engine-mechanical-66l-2-of-5) .
2. Loosen the clamp (1) that fastens the left air cooler duct (4) to the turbocharger.
3. Remove the left charge air cooler inlet duct connector (4) from the turbocharger.
4. Use the clamp to attach the J 45091-2 from the J 46091: Tester to the duct connector and tighten the clamp to 8 N.m (70 lb in).
5. Secure the J 45091-2 (1) safety cable (2) to a safe location (3).
6. Attach the gage/regulator assembly from the J 46091: Tester to the quick disconnect fitting on the J 45091-2.
7. Remove both fender wheelhouse liners. Refer to «Front Wheelhouse Liner Replacement - Right Side (Chevrolet)»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/frames-subframes-crossmembers/#frame-and-underbody) or «Front Wheelhouse Liner Replacement - Right Side (GMC)»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/frames-subframes-crossmembers/#frame-and-underbody) and «Front Wheelhouse Liner Replacement - Left Side (Chevrolet)»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/frames-subframes-crossmembers/#frame-and-underbody) or «Front Wheelhouse Liner Replacement - Left Side (GMC)»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/frames-subframes-crossmembers/#frame-and-underbody) .
8. Remove the air cleaner assembly. Refer to «Air Cleaner Assembly Replacement»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/testing-diagnostics/#engine-controls-and-fuel-66l-introduction-1-of-2) .
9. Remove the air cleaner box tray bracket.

Leak Test - Air Pressure Application

Note. Charge air coolers are not required to be leak proof. DO NOT test the cooler for leakage by submerging it in a radiator test tank. Almost all charge air cooler units will show leakage if they are submerged.

1. Connect the filtered air supply to the air valve on the gage/regulator assembly.
2. Open the air valve slowly, increasing the air pressure in 34-69 kPa (5-10 psi) increments while listening for air leaks. Continue increasing the air pressure until the gage reads 205 kPa (30 psi).
3. Close the air valve and monitor the gage for 15 seconds. Note any decrease in air pressure.
4. Repeat the test 3 times to verify the results.

Leak Test Fails

If the pressure drop is more than 34 kPa (5 psi) in 15 seconds, the leak test has failed. Perform the following procedure

1. Inspect for air leaks using a pump spray bottle to apply a soapy solution to the pipes/hoses, charge air cooler hose connections, and charge air cooler core. Observe for bubbles.
2. Replace or tighten the affected component as necessary.
3. Retest the CAC system. If no other leaks are found, assemble the vehicle and clear the DTC information with a scan tool.
4. Perform a DPF Service Regeneration with a scan tool. Refer to «Diesel Particulate Filter (DPF) Service Regeneration»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/testing-diagnostics/#engine-controls-and-fuel-66l-introduction-1-of-2__diesel-particulate-filter-dpf-service-regeneration)

Leak Test Passes

If the pressure drop is less than 34 kPa (5 psi) in 15 seconds, the leak test passes. Remove the tester by performing the following procedure

1. Slowly bleed the air from the cooler by depressing the relief valve on the adapter plate.
2. Remove the air hose, gage/regulator assembly, and both adapters.
3. Connect the charge air hose to the turbocharger and tighten the clamp to 8 N.m (70 lb in).
4. Remove the adapter plate and install the intake air heater. Refer to «Intake Air Heater Replacement»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/testing-diagnostics/#engine-controls-and-fuel-66l-introduction-1-of-2) .
5. Install both fender wheelhouse liners. Refer to «Front Wheelhouse Liner Replacement - Right Side (Chevrolet)»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/frames-subframes-crossmembers/#frame-and-underbody) or «Front Wheelhouse Liner Replacement - Right Side (GMC)»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/frames-subframes-crossmembers/#frame-and-underbody) and «Front Wheelhouse Liner Replacement - Left Side (Chevrolet)»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/frames-subframes-crossmembers/#frame-and-underbody) or «Front Wheelhouse Liner Replacement - Left Side (GMC)»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/frames-subframes-crossmembers/#frame-and-underbody) .
6. Install the air cleaner assembly. Refer to «Air Cleaner Assembly Replacement»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/testing-diagnostics/#engine-controls-and-fuel-66l-introduction-1-of-2) .
7. Install the air cleaner boxy tray bracket.

1. Perform the «Diagnostic System Check - Vehicle»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/oem-general-information/#vehicle-diagnostic-information__diagnostic-system-check-vehicle) prior to using this diagnostic procedure.
2. Review «Strategy Based Diagnosis»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/oem-general-information/#vehicle-diagnostic-information__strategy-based-diagnosis) for an overview of the diagnostic approach.
3. «Diagnostic Procedure Instructions»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/oem-general-information/#vehicle-diagnostic-information__diagnostic-procedure-instructions) provides an overview of each diagnostic category.

The purpose of the inspection maintenance (I/M) complete system set procedure is to satisfy the enabled criteria necessary to execute all of the I/M system monitors. When all system monitors are completed, the I/M system status indicators are set to YES. Perform this procedure when more than one of the I/M system status indicators are set to NO.

Conditions for Updating the I/M System Status

Each system monitor requires at least one, and sometimes several, diagnostic tests. The results of these tests are reported by a DTC. A system monitor completes when either all DTCs comprising the monitor have run and passed, or any DTC comprising the monitor has illuminated the malfunction indicator lamp (MIL). Once the monitor completes, the I/M system status display will indicate YES in the Completed column. For example, when the Misfire Monitoring System Status display indicates YES, all of the misfire components have been diagnosed. The I/M system status will indicate NO in the Completed column when any of the required DTCs for that system have not run. The following is a list of conditions that would set the I/M System Status indicators to NO

1. The vehicle is new from the factory and has not yet been driven through the necessary drive conditions to complete the system monitor.
2. The battery has been disconnected or discharged below operating voltage.
3. The control module power or ground has been interrupted.
4. The control module has been reprogrammed.
5. The control module DTCs have been cleared as part of a service procedure.

Monitored Emission Control Systems

The OBD II system monitors all emission control systems that are on-board. Not all vehicles have a full complement of emission control systems. For example, a vehicle may not be equipped with exhaust gas recirculation (EGR). The OBD II regulations require monitoring of the following

1. Comprehensive component monitoring-Emission related inputs and outputs
2. The EGR system
3. Misfire monitoring
4. Catalyst monitoring

For the specific DTCs required for each system, refer to Inspection/Maintenance (I/M) System DTC Table .

Review the I/M system status indicators. All I/M system status indictors should report YES.

1. Repair any DTCs or driveability concerns.
2. Review any service bulletins for software updates that may prevent the required DTCs from running.
3. Perform any reprogramming or repairs indicated by the service bulletins. If more than one system indicates a NO status or did not update to YES, refer to «Inspection/Maintenance (I/M) Complete System Set Procedure»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/testing-diagnostics/#engine-controls-and-fuel-66l-troubleshooting-diagnosis) .

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

Inspection/Maintenance (I/M) System DTC Table

1. Perform the «Diagnostic System Check - Vehicle»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/oem-general-information/#vehicle-diagnostic-information__diagnostic-system-check-vehicle) prior to using this diagnostic procedure.
2. Review «Strategy Based Diagnosis»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/oem-general-information/#vehicle-diagnostic-information__strategy-based-diagnosis) for an overview of the diagnostic approach.
3. «Diagnostic Procedure Instructions»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/oem-general-information/#vehicle-diagnostic-information__diagnostic-procedure-instructions) provides an overview of each diagnostic category.

The purpose of the inspection/maintenance (I/M) complete system set procedure is to satisfy the enabled criteria necessary to execute all of the I/M system monitors. When all system monitors are completed, the I/M system status indicators are set to YES. Perform this procedure when more than one of the I/M system status indicators are set to NO.

Conditions for Meeting a Cold Engine

1. The battery voltage is between 11-18 volts.
2. The engine coolant temperature (ECT) is between 57-104°C (133-219°F).
3. The intake air temperature (IAT) is more than 5.25°C (41.5°F).
4. The barometric pressure (BARO) is more than 74 kPa.

If there is an impending failure, the system may require more time than was allotted in the system set procedure. If any DTCs do not run and the DTC is set, review the appropriate scan tool data list and service information. This will give an indication of why the DTCs do not run. Some may abort due to changes in the conditions while running. For example, changes in engine load, such as a cooling fan or A/C compressor clutch turning ON, may cause a DTC to abort. If the I/M system status does not update to YES, the procedure can be repeated until a YES status is achieved.

Review the I/M system status indicators. All I/M system status indictors should report YES.

1. Ensure the vehicle is within the Conditions for Running, as specified in the supporting text.
2. Turn OFF all of the accessories, e.g., A/C, blower fan, etc.
3. Set the vehicle parking brake.
4. Verify the transmission is in PARK for automatic transmissions, and NEUTRAL for manual transmissions.
5. Start and allow the engine to idle for 2 minutes.
6. Refer to «Inspection/Maintenance (I/M) System DTC Table»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/testing-diagnostics/#engine-controls-and-fuel-66l-troubleshooting-diagnosis__inspectionmaintenance-im-system-dtc-table) to determine which DTCs are required to run in order to update the misfire monitoring I/M system status to YES.
7. Observe the Not Ran Since Code Cleared display with a scan tool and determine which of the DTCs required for a YES status have not run.
8. Enter the DTC number in the Specific DTC menu of the scan tool.
9. Operate the vehicle within the Conditions for Running the DTC, located in the supporting text for the diagnostic table of the DTC.
10. Repeat steps 8 and 9 for any additional required DTCs that have not run. If the I/M System Status did not update to YES, refer to «Diagnostic Aids»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/testing-diagnostics/#engine-controls-and-fuel-66l-troubleshooting-diagnosis) .
11. Observe the emission related DTC portion of the I/M system status display with a scan tool. If the scan tool indicates any DTCs are set, refer to «Diagnostic Trouble Code (DTC) List - Vehicle»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/oem-general-information/#vehicle-diagnostic-information__diagnostic-trouble-code-dtc-list) .

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

1. Perform the «Diagnostic System Check - Vehicle»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/oem-general-information/#vehicle-diagnostic-information__diagnostic-system-check-vehicle) prior to using this diagnostic procedure.
2. Review «Strategy Based Diagnosis»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/oem-general-information/#vehicle-diagnostic-information__strategy-based-diagnosis) for an overview of the diagnostic approach.
3. «Diagnostic Procedure Instructions»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/oem-general-information/#vehicle-diagnostic-information__diagnostic-procedure-instructions) provides an overview of each diagnostic category.

The fuel filter/heater element housing consists of a water separator, a hand prime pump, fuel heater element and a filter element. Fuel passes through the fuel heater, which is operated by a built-in thermostatic switch. The thermostatic switch opens or closes to turn the heater ON or OFF, depending on temperature. Fuel then passes through the filter and the water coalesce, where the droplets of water in the fuel combine into larger drops that fall into the water reservoir in the filter. When fuel flows to the fuel injection pump, the fuel is clean and free of water.

Schematic Reference

Engine Controls Schematics

Electrical Information Reference

1. «Circuit Testing»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-service-troubleshooting-diagnosis__circuit-testing)
2. «Connector Repairs»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-service-troubleshooting-diagnosis__connector-repairs)
3. «Testing for Intermittent Conditions and Poor Connections»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-service-troubleshooting-diagnosis__testing-for-intermittent-conditions-and-poor)
4. «Wiring Repairs»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-service-troubleshooting-diagnosis__wiring-repairs)

Check the Water in Fuel lamp for proper operation. Refer to Water in Fuel Indicator Malfunction .

1. Disconnect the fuel heater harness connector from the top of the fuel filter/heater element housing.
2. Turn ON the ignition with the engine OFF.
3. Probe the fuel heater ignition 1 voltage circuit with a test lamp connected to a good ground. If the test lamp did not illuminate repair the short to ground or open in the ignition 1 voltage circuit.
4. Probe the fuel heater ground circuit at the fuel filter/heater element housing with a test lamp connected to battery voltage. If the test lamp did not illuminate repair the open in the ground circuit between the fuel filter/heater element housing and the engine ground.
5. Remove the fuel filter from the fuel filter/heater element housing. Test the ignition 1 voltage circuit and the ground circuit for an open in the fuel filter/heater element housing. If either circuit tested open replace the fuel heater element.
6. If all circuits test normal, test the fuel heater thermostatic switch for proper operation. Refer to «Component Testing»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/testing-diagnostics/#engine-controls-and-fuel-66l-troubleshooting-diagnosis__component-testing) .

Component Testing

1. Remove the fuel filter/heater element housing from the vehicle.
2. Connect the ignition 1 voltage circuit of the fuel heater to a battery voltage source and connect the ground circuit of the fuel heater to a ground.
3. Cool the thermostatic switch of the fuel heater with ice.
4. Observe the heating element. If the thermostatic switch does not turn on the heater element when the temperature is between -8.4°C and +15.4°C (+16.9°F and +59.8°F) replace the fuel filter/heater element housing.

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

Fuel Heater Replacement

1. Perform the «Diagnostic System Check - Vehicle»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/oem-general-information/#vehicle-diagnostic-information__diagnostic-system-check-vehicle) prior to using this diagnostic procedure.
2. Review «Strategy Based Diagnosis»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/oem-general-information/#vehicle-diagnostic-information__strategy-based-diagnosis) for an overview of the diagnostic approach.
3. «Diagnostic Procedure Instructions»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/oem-general-information/#vehicle-diagnostic-information__diagnostic-procedure-instructions) provides an overview of each diagnostic category.

The fuel filter/heater element housing consists of a water separator, a hand prime pump, fuel heater element and a filter element. Fuel passes through the fuel heater, which is operated by a built-in thermostatic switch. The thermostatic switch opens or closes to turn the heater ON or OFF, depending on temperature. Fuel then passes through the filter and the water coalesce, where the droplets of water in the fuel combine into larger drops that fall into the water reservoir in the filter. When fuel flows to the fuel injection pump, the fuel is clean and free of water.

Schematic Reference

Engine Controls Schematics

Electrical Information Reference

1. «Circuit Testing»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-service-troubleshooting-diagnosis__circuit-testing)
2. «Connector Repairs»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-service-troubleshooting-diagnosis__connector-repairs)
3. «Testing for Intermittent Conditions and Poor Connections»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-service-troubleshooting-diagnosis__testing-for-intermittent-conditions-and-poor)
4. «Wiring Repairs»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-service-troubleshooting-diagnosis__wiring-repairs)

Check the Water in Fuel lamp for proper operation. Refer to Water in Fuel Indicator Malfunction .

1. Turn ON the ignition, with the engine OFF.
2. Disconnect the fuel heater connector.
3. With the fuel temperature above 21°C (70°F), test for continuity between the ignition 1 voltage terminal and the fuel filter/heater element housing. If continuity was present, the thermostatic switch is stuck ON. Replace the fuel heater element.

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

Fuel Heater Replacement

1. Perform the «Diagnostic System Check - Vehicle»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/oem-general-information/#vehicle-diagnostic-information__diagnostic-system-check-vehicle) prior to using this diagnostic procedure.
2. Review «Strategy Based Diagnosis»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/oem-general-information/#vehicle-diagnostic-information__strategy-based-diagnosis) for an overview of the diagnostic approach.
3. «Diagnostic Procedure Instructions»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/oem-general-information/#vehicle-diagnostic-information__diagnostic-procedure-instructions) provide an overview of each diagnostic category.

Diagnostic Fault Information

Schematic Reference

Engine Controls Schematics

Connector End View Reference

Component Connector End Views

Electrical Information Reference

1. «Circuit Testing»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-service-troubleshooting-diagnosis__circuit-testing)
2. «Connector Repairs»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-service-troubleshooting-diagnosis__connector-repairs)
3. «Testing for Intermittent Conditions and Poor Connections»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-service-troubleshooting-diagnosis__testing-for-intermittent-conditions-and-poor)
4. «Wiring Repairs»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-service-troubleshooting-diagnosis__wiring-repairs)

Scan Tool Reference

Control Module References for scan tool information

Ignition ON, observe the scan tool High Idle switch parameter while exercising the switch. The reading should change between ON/OFF.

1. Ignition OFF, disconnect the harness connector at the high idle switch.
2. Test for less than 5 ohms between the ground circuit terminal A and ground. If greater than 5 ohms, test the ground circuit for an open/high resistance.
3. Ignition ON, verify the scan tool High Idle switch parameter is OFF. If not OFF, test the signal circuit for a short to ground. If the circuit tests normal, replace the ECM.
4. Install a 3A fused jumper wire between the signal circuit terminal C and ground. Verify the scan tool High Idle switch parameter is ON. If not ON, test the signal circuit for a short to voltage or an open/high resistance. If the circuit tests normal, replace the ECM.
5. If all circuits test normal, test or replace the high idle switch.

1. Ignition OFF, disconnect the harness connector at the high idle switch.
2. Test for infinite resistance between the signal terminal C and the ground circuit terminal A with the switch in the open position. If less than infinite resistance, replace the high idle switch.
3. Test for less than 1 ohm between the signal terminal C and the ground terminal A with the switch in the closed position. If greater than 1 ohm, replace the high idle switch.

See also:
• Diagnostic System Check - Vehicle
• Strategy Based Diagnosis
• Diagnostic Procedure Instructions
• Control Module References
• Component Connector End Views
• Testing for Intermittent Conditions and Poor Connections
• Fuel System Specifications
• Valve Rocker Arm and Shaft Cleaning and Inspection
• Engine Compression Test
• Camshaft and Bearings Cleaning and Inspection
• Oil Consumption Diagnosis
• Temperature Versus Resistance (ECT Sensors)
• Temperature Versus Resistance (EGR Temperature Sensors)
• Temperature Versus Resistance (EGT Sensors)
• Temperature Versus Resistance (Fuel Temperature Sensor)
• Temperature Versus Resistance (IAT Sensor 1)
• Temperature Versus Resistance (IAT Sensor 2)
• Symptoms - Engine Electrical
• Restricted Exhaust
• DTC P0101
• Air Conditioning (A/C) System Performance Test (Diesel Engine)
• Air Conditioning (A/C) System Performance Test (HP2 )
• Engine Mount Inspection
• Engine Overheating
• Radiator Cleaning
• Loss of Coolant
• Instrument Cluster Schematics
• Circuit Testing
• Connector Repairs
• Wiring Repairs
• Powertrain Diagnostic Trouble Code (DTC) Type Definitions
• Diagnostic Repair Verification
• Symptoms - Engine Exhaust
• Fuel System Description
• Fastener Tightening Specifications
• Diagnostic Trouble Code (DTC) List - Vehicle
• Symptoms - Engine Mechanical
• Fuel System Cleaning
• Charge Air Cooler Warning
• Front Wheelhouse Liner Replacement - Right Side (Chevrolet)
• Fastener Caution
• Lifting and Jacking the Vehicle
• Intake Manifold Cover Replacement
• Diesel Particulate Filter (DPF) Service Regeneration
• DTC P0420
• Charge Air Cooler Diagnosis (Induction System Smoke Test)
• Contaminants-in-Fuel Diagnosis
• Fuel Leak Diagnosis
• Fuel Pressure Regulator Diagnosis
• Inspection/Maintenance (I/M) System DTC Table
• Component Testing