Engine Control System & Fuel System - 4.3l - Troubleshooting and Diagnosis GMC Sierra II

Diagnostic Instructions

1. Perform the «Diagnostic System Check - Vehicle»(/gmc/sierra/ii-2006-2014/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures) prior to using this diagnostic procedure.
2. Review «Strategy Based Diagnosis»(/gmc/sierra/ii-2006-2014/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures__strategy-based-diagnosis) for an overview of the diagnostic approach.
3. «Diagnostic Procedure Instructions»(/gmc/sierra/ii-2006-2014/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures__diagnostic-procedure-instructions) provides an overview of each diagnostic category.

Symptoms Description

Symptoms cover conditions that are not covered DTCs. Certain conditions can cause multiple symptoms. These conditions are listed together under Symptoms Testing. Conditions that may only cause certain symptoms are listed separately under Additional Symptoms Test. Perform the Symptoms Testing before using the Additional Symptoms Tests. Poor Fuel Fill Quality test may be performed separately from the Symptoms Testing and Additional Symptoms Tests procedures.

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 diagnostic trouble codes (DTCs) that are stored.
3. Ensure that the scan tool data is within a normal operating range.
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 «Wiring Repairs»(/gmc/sierra/ii-2006-2014/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__wiring-repairs) .
2. Ensure that the vacuum hoses are not split, kinked, and properly connected, as shown on the Vehicle Emission Control Information label.
3. Ensure that the air filter is clean and free from restrictions.
4. Ensure that there is no water intrusion in connectors terminals and components.
5. Inspect the air intake ducts for the following conditions: Collapsed Damaged areas Looseness Incorrect installation Leaking
6. Inspect for air leaks at the throttle body mounting area, the mass air flow (MAF) sensor and intake manifold sealing surfaces.
7. Inspect the wiring harness for the following conditions: Poor connections Pinches Cuts
8. Inspect for loose, damaged, unseated, or missing sensors/components.
9. Inspect the terminals for corrosion and correct contact.

Symptoms Testing

Backfire, Cuts Out/Misses, Detonation/Spark Knock, Dieseling/Run-On, Hard Start, Hesitation/Sag/Stumble, Lack of Power/Sluggishness/Sponginess, Poor Fuel Economy, Rough, Unstable, or Incorrect Idle and Stalling, or Surges/Chuggles

1. Test for the following conditions: The fuel system for the following: Correct fuel pressure-Refer to «Fuel System Diagnosis»(/gmc/sierra/ii-2006-2014/remont/testing-diagnostics/#engine-control-system-fuel-system-43l-troubleshooting-and-diagnosis) Fuel injectors that are leaking or improper operation-Refer to «Fuel Injector Diagnosis (J39021 or Tech 2)»(/gmc/sierra/ii-2006-2014/remont/testing-diagnostics/#engine-control-system-fuel-system-43l-troubleshooting-and-diagnosis) or «Fuel Injector Diagnosis (CH47976)»(/gmc/sierra/ii-2006-2014/remont/testing-diagnostics/#engine-control-system-fuel-system-43l-troubleshooting-and-diagnosis) . Contaminated or a poor fuel quality condition-Refer to «Alcohol/Contaminants-in-Fuel Diagnosis (Without Special Tool)»(/gmc/sierra/ii-2006-2014/remont/testing-diagnostics/#engine-control-system-fuel-system-43l-troubleshooting-and-diagnosis) or «Alcohol/Contaminants-in-Fuel Diagnosis (Special Tool)»(/gmc/sierra/ii-2006-2014/remont/testing-diagnostics/#engine-control-system-fuel-system-43l-troubleshooting-and-diagnosis) . The ignition system for the following: Spark plugs for incorrect heat range or an abnormal condition-Refer to «Spark Plug Inspection»(/gmc/sierra/ii-2006-2014/remont/testing-diagnostics/#engine-control-system-fuel-system-43l-repair-instructions__spark-plug-inspection) . For diagnosis of coolant or oil fouled spark plugs, refer to «Loss of Coolant»(/gmc/sierra/ii-2006-2014/remont/cooling-system-mechanical/#engine-cooling-system-non-hybrid__loss-of-coolant) or «Symptoms - Engine Mechanical»(/gmc/sierra/ii-2006-2014/remont/mechanical/#engine-mechanical-43l) . Wet down the secondary ignition system with water from a spray bottle. Wetting down the secondary ignition system may help locate damaged or deteriorated components. Look/listen for arcing or misfiring as the water is applied. Weak spark using the J 26792 Spark Tester-Refer to «Electronic Ignition System Diagnosis»(/gmc/sierra/ii-2006-2014/remont/testing-diagnostics/#engine-control-system-fuel-system-43l-troubleshooting-and-diagnosis) . The operation of the transmission torque converter clutch (TCC)-The scan tool should indicate an engine speed drop when the TCC is commanded ON. The operation of the A/C compressor Items that can cause an engine to run rich or lean. Inspect the heated oxygen sensors (HO2S). The HO2S should respond quickly to different throttle positions. CAUTION: Refer to «Heated Oxygen and Oxygen Sensor Caution»(/gmc/sierra/ii-2006-2014/remont/oem-general-information/#dangers-warnings-and-cautions__heated-oxygen-and-oxygen-sensor-caution) . Water intrusion in the HO2S connector NOTE: The embossed arrows on the mass air flow (MAF) sensor indicate the direction of the intake air flow. The arrows must point toward the engine. Inspect the MAF sensor installation. A MAF sensor that is incorrectly installed may cause a hard start. Install the MAF in the proper direction. Refer to «Mass Airflow Sensor with Intake Air Temperature Sensor Replacement»(/gmc/sierra/ii-2006-2014/remont/testing-diagnostics/#engine-control-system-fuel-system-43l-repair-instructions) . Inspect the mass air flow (MAF) sensor connections. Engine oil contaminated by fuel The engine for the following mechanical failures-Refer to «Symptoms - Engine Mechanical»(/gmc/sierra/ii-2006-2014/remont/mechanical/#engine-mechanical-43l) : Excessive oil in the combustion chamber or leaking valve seals Incorrect cylinder compression Sticking or leaking valves Worn camshaft lobes Incorrect valve timing Worn rocker arms Broken valve springs Excessive carbon buildup in the combustion chambers-Clean the chambers with top engine cleaner. Follow the instructions on the can. Incorrect engine parts Vacuum hoses for splits or kinks-Verify that the routing and connections are as shown on the Vehicle Emission Control Information label. Knock sensor (KS) system for excessive spark retard activity The exhaust system components for the following: Physical damage or possible internal failure The three-way catalytic converters for a restriction For more information, refer to «Symptoms - Engine Exhaust»(/gmc/sierra/ii-2006-2014/remont/exhaust/#engine-exhaust-system__symptoms-engine-exhaust) . Electromagnetic interference (EMI) on the reference circuit can cause a misfire condition. You can usually detect EMI with a scan tool by monitoring the engine speed parameter. A sudden increase in the engine speed parameter with little change in actual engine speed indicates that EMI is present. Inspect the high voltage components near the ignition control circuit if a condition exists. The crankcase ventilation valve for proper operation-Refer to «Crankcase Ventilation System Inspection/Diagnosis»(/gmc/sierra/ii-2006-2014/remont/mechanical/#engine-mechanical-43l) . Evaporative emission (EVAP) canister purge solenoid that is stuck open The engine cooling system for the following conditions: The thermostat is the correct heat range. Refer to «Thermostat Diagnosis»(/gmc/sierra/ii-2006-2014/remont/cooling-system-mechanical/#engine-cooling-system-non-hybrid) . Proper engine coolant level-Refer to «Cooling System Draining and Filling (Vac-N-Fill)»(/gmc/sierra/ii-2006-2014/remont/cooling-system-mechanical/#engine-cooling-system-non-hybrid__cooling-system-draining-and-filling-vac-n-fill) or «Cooling System Draining and Filling (Static Fill)»(/gmc/sierra/ii-2006-2014/remont/cooling-system-mechanical/#engine-cooling-system-non-hybrid__cooling-system-draining-and-filling-static) .
2. If the above conditions do not address the symptom, refer to the additional symptoms tests.

Additional Symptoms Tests

Hard Start

1. Test the engine coolant temperature (ECT) sensor. Compare the ECT sensor value to the intake air temperature (IAT) sensor value on a cold engine. The ECT and IAT sensor values should be within ± 3°C (5°F). If the ECT sensor is out of range with the IAT sensor, test the resistance of the ECT sensor. Refer to «Temperature Versus Resistance»(/gmc/sierra/ii-2006-2014/remont/testing-diagnostics/#engine-control-system-fuel-system-43l-specifications__temperature-versus-resistance) for resistance specifications. Replace the ECT sensor if the resistance is not within specification. Refer to «Engine Coolant Temperature Sensor Replacement»(/gmc/sierra/ii-2006-2014/remont/testing-diagnostics/#engine-control-system-fuel-system-43l-repair-instructions) . If the sensor is within the specification, test the ECT circuits for a high resistance.
2. Test the idle air control (IAC) system.
3. Test the fuel pump relay operation. The fuel pump should turn ON for 2 seconds when the ignition is turned ON. Refer to «Fuel System Diagnosis»(/gmc/sierra/ii-2006-2014/remont/testing-diagnostics/#engine-control-system-fuel-system-43l-troubleshooting-and-diagnosis) .

Hesitation, Sag, Stumble

1. Test the manifold absolute pressure (MAP) sensor. Refer to «DTC P0106»(/gmc/sierra/ii-2006-2014/remont/testing-diagnostics/#engine-control-system-fuel-system-48l-53l-60l-62l-dtc-p0010-to-dtc-p0232dtc-p025a) .
2. Test the generator. Refer to «DTC P0106»(/gmc/sierra/ii-2006-2014/remont/testing-diagnostics/#engine-control-system-fuel-system-43l-dtc-p0016-to-p0336) . Repair the charging system if the generator output voltage is less than 9 volts or more than 16 volts.

Poor Fuel Economy

1. Heavy loads being carried or towed.
2. Acceleration rate too much or too often.
3. Inspect for foreign material accumulation in the throttle bore, and for carbon deposits on the throttle plate and shaft. Also inspect for throttle body tampering.

Poor Fuel Fill Quality

Test for the following conditions that is applicable to the current symptom.

Difficult to Fill

1. Restricted vent lines
2. The evaporative emission (EVAP) vent valve is stuck closed
3. High fuel temperature
4. A condition with the internal components of the fuel tank assembly. For more information, refer to
5. «Fuel System Description»(/gmc/sierra/ii-2006-2014/remont/testing-diagnostics/#engine-control-system-fuel-system-43l-description-and-operation)
6. «Evaporative Emission Control System Description»(/gmc/sierra/ii-2006-2014/remont/testing-diagnostics/#engine-control-system-fuel-system-43l-description-and-operation)

Fuel Odor

1. Saturated EVAP canister-Refer to «Evaporative Emission Control System Description»(/gmc/sierra/ii-2006-2014/remont/testing-diagnostics/#engine-control-system-fuel-system-43l-description-and-operation) .
2. A condition with the internal components of the fuel tank assembly-Refer to «Fuel System Description»(/gmc/sierra/ii-2006-2014/remont/testing-diagnostics/#engine-control-system-fuel-system-43l-description-and-operation) .

1. Perform the «Diagnostic System Check - Vehicle»(/gmc/sierra/ii-2006-2014/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures) prior to using this diagnostic procedure.
2. «Strategy Based Diagnosis»(/gmc/sierra/ii-2006-2014/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures__strategy-based-diagnosis) for an overview of the diagnostic approach.
3. «Diagnostic Procedure Instructions»(/gmc/sierra/ii-2006-2014/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures__diagnostic-procedure-instructions) provide an overview of each diagnostic category.

Circuit/System Description

Ignition voltage is supplied to the malfunction indicator lamp (MIL). The engine control module (ECM) turns the MIL ON by grounding the MIL control circuit.

Reference Information

Schematic Reference

1. «Instrument Cluster Schematics»(/gmc/sierra/ii-2006-2014/remont/gauges-instrument-panels/#instrument-panel-system-displays-gauges)
2. «Engine Controls Schematics»(/gmc/sierra/ii-2006-2014/remont/testing-diagnostics/#engine-control-system-fuel-system-43l-wiring-schematic-and-fuel-hosepipes-routing-diagrams)

Connector End View Reference

Component Connector End Views

Electrical Information Reference

1. «Circuit Testing»(/gmc/sierra/ii-2006-2014/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__circuit-testing)
2. «Connector Repairs»(/gmc/sierra/ii-2006-2014/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__connector-repairs)
3. «Testing for Intermittent Conditions and Poor Connections»(/gmc/sierra/ii-2006-2014/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__testing-for-intermittent-conditions-and-poor)
4. «Wiring Repairs»(/gmc/sierra/ii-2006-2014/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__wiring-repairs)

Scan Tool Reference

Control Module References for scan tool information

Circuit/System Verification

Ignition ON, the MIL should turn ON and OFF when commanded with a scan tool.

Circuit/System Testing

1. Ignition OFF, disconnect the harness connector at the instrument panel cluster (IPC).
2. Ignition ON, verify that a test lamp illuminates between the ignition circuit and ground. If the test lamp does not illuminate, test the 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.
3. Connect a test lamp between the control circuit and the ignition circuit.
4. Command the MIL ON and OFF with a scan tool. The test lamp should turn ON and OFF when changing between the commanded states. If the test lamp is always ON, test the control circuit for a short to ground. If the circuit tests normal, replace the ECM. If the test lamp is always OFF, test the control 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, replace the IPC.

Repair Procedures

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

1. «Control Module References»(/gmc/sierra/ii-2006-2014/remont/communication-devices/#programming-and-setup-all-systems__control-module-references) for ECM replacement, setup, and programming
2. «Instrument Cluster Replacement (Without RPO SLT)»(/gmc/sierra/ii-2006-2014/remont/gauges-instrument-panels/#instrument-panel-system-displays-gauges) or «Instrument Cluster Replacement (With RPO SLT)»(/gmc/sierra/ii-2006-2014/remont/gauges-instrument-panels/#instrument-panel-system-displays-gauges)

1. Perform the «Diagnostic System Check - Vehicle»(/gmc/sierra/ii-2006-2014/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures) prior to using this diagnostic procedure.
2. Review «Strategy Based Diagnosis»(/gmc/sierra/ii-2006-2014/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures__strategy-based-diagnosis) for an overview of the diagnostic approach.
3. «Diagnostic Procedure Instructions»(/gmc/sierra/ii-2006-2014/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures__diagnostic-procedure-instructions) provide an overview of each diagnostic category.

This Engine Cranks but Does Not Run diagnostic is an organized approach to identify a condition which causes the engine to crank but does not continue to run. This diagnostic directs the service technician to the appropriate system diagnosis. This diagnostic assumes the vehicle system voltage levels are adequate for starter motor operation. Refer to Battery Inspection/Test and Engine Cranks Slowly . The fuel level supply must be adequate, and the fuel quality must be able to sustain the combustion process.

Diagnostic Aids

1. When disconnecting electrical connectors or removing fuses and relays from a fuse block, always inspect both mating electrical terminals for corrosion and terminal tightness.
2. Use the J 35616 for any test that requires probing the underhood fuse block terminals, component wire harness terminals, or the ECM wire harness terminals.

Schematic Reference

Engine Controls Schematics

Connector End View Reference

1. «Component Connector End Views»(/gmc/sierra/ii-2006-2014/remont/body-electrical/#wiring-systems-and-power-management-component-connector-end-views-index)
2. «Electrical Center Identification Views»(/gmc/sierra/ii-2006-2014/remont/electrical-component-locations/#wiring-systems-and-power-management-component-locator-electrical-center-identification-views)

Electrical Information Reference

1. «Circuit Testing»(/gmc/sierra/ii-2006-2014/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__circuit-testing)
2. «Connector Repairs»(/gmc/sierra/ii-2006-2014/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__connector-repairs)
3. «Testing for Intermittent Conditions and Poor Connections»(/gmc/sierra/ii-2006-2014/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__testing-for-intermittent-conditions-and-poor)
4. «Wiring Repairs»(/gmc/sierra/ii-2006-2014/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__wiring-repairs)

Scan Tool Reference

Control Module References for scan tool information

Special Tools

1. J 35616 Connector Test Adapter Kit
2. J 34730-1A Fuel Pressure Gauge

Attempt to start the engine. The engine should start and run.

1. If the vehicle passes the Circuit/System Verification test, then refer to «Testing for Intermittent Conditions and Poor Connections»(/gmc/sierra/ii-2006-2014/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__testing-for-intermittent-conditions-and-poor) .

1. Crank the engine while observing the scan tool Vehicle DTC Information. If any of the following DTCs are set, diagnose these first: DTC P0117, P0118, P0122, P0123, P0201-P0208, P0222, P0223, P0335, P0336, P0351-P0358, P0513, P0562, P0563, P0601-P0604, P0606, P0607, P062F, P0633, P0685, P0690, P1516, P1631, P1682, or P2610. Refer to «Diagnostic Trouble Code (DTC) List - Vehicle»(/gmc/sierra/ii-2006-2014/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures__diagnostic-trouble-code-dtc-list) .
2. With the ignition ON and the engine OFF, test the fuses that are supplied ignition 1 voltage by the powertrain relay. The test lamp should illuminate ON for each test point of the fuses. If the test lamp does not illuminate on, for at least one test point of each fuse, refer to «DTC P0685, P0689, or P0690»(/gmc/sierra/ii-2006-2014/remont/testing-diagnostics/#engine-control-system-fuel-system-43l-dtc-p0340-to-dtc-p2544) .
3. Crank the engine while observing the scan tool engine speed parameter. If engine RPM is not indicated, refer to «DTC P0335»(/gmc/sierra/ii-2006-2014/remont/testing-diagnostics/#engine-control-system-fuel-system-43l-dtc-p0016-to-p0336) or «DTC P0336»(/gmc/sierra/ii-2006-2014/remont/testing-diagnostics/#engine-control-system-fuel-system-43l-dtc-p0016-to-p0336) .
4. Install a spark plug tester onto one ignition module/coil assembly, on each bank of the engine.
5. Crank the engine while observing both spark plug testers. Both spark plug testers should spark. If spark is not observed, is inconsistent, or weak on either spark plug tester, refer to «Electronic Ignition System Diagnosis»(/gmc/sierra/ii-2006-2014/remont/testing-diagnostics/#engine-control-system-fuel-system-43l-troubleshooting-and-diagnosis) .
6. With the ignition ON and the engine OFF, command the fuel pump ON and OFF with the scan tool. The fuel pump should energize when commanded ON, and de-energize when commanded OFF. If the fuel pump does not turn ON and OFF, refer to «Fuel System Diagnosis (Without FPCM)»(/gmc/sierra/ii-2006-2014/remont/testing-diagnostics/#engine-control-system-fuel-system-48l-53l-60l-62l-troubleshooting-and-diagnosis) or «Fuel System Diagnosis (FPCM)»(/gmc/sierra/ii-2006-2014/remont/testing-diagnostics/#engine-control-system-fuel-system-48l-53l-60l-62l-troubleshooting-and-diagnosis) .
7. Turn OFF the ignition.
8. Install the J 34730-1A Fuel Pressure Gauge. With the ignition ON and the engine OFF, command the fuel pump ON several times with the scan tool. Refer to «Fuel System Diagnosis»(/gmc/sierra/ii-2006-2014/remont/testing-diagnostics/#engine-control-system-fuel-system-43l-troubleshooting-and-diagnosis) for the fuel pressure specification.
9. Inspect for the following conditions: Compare the actual engine coolant temperature to the ECT parameter Filter and air intake system for restrictions and obstructions Test the fuel for contamination-Refer to «Alcohol/Contaminants-in-Fuel Diagnosis (Without Special Tool)»(/gmc/sierra/ii-2006-2014/remont/testing-diagnostics/#engine-control-system-fuel-system-43l-troubleshooting-and-diagnosis) or «Alcohol/Contaminants-in-Fuel Diagnosis (Special Tool)»(/gmc/sierra/ii-2006-2014/remont/testing-diagnostics/#engine-control-system-fuel-system-43l-troubleshooting-and-diagnosis) . Inspect the spark plugs-Refer to «Spark Plug Inspection»(/gmc/sierra/ii-2006-2014/remont/testing-diagnostics/#engine-control-system-fuel-system-43l-repair-instructions__spark-plug-inspection) . Test the exhaust system for restrictions-Refer to «Restricted Exhaust»(/gmc/sierra/ii-2006-2014/remont/exhaust/#engine-exhaust-system) . Engine mechanical conditions, such as worn timing chain, sprocket gears, low compression, etc-Refer to «Symptoms - Engine Mechanical»(/gmc/sierra/ii-2006-2014/remont/mechanical/#engine-mechanical-43l) .

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

1. Perform the «Diagnostic System Check - Vehicle»(/gmc/sierra/ii-2006-2014/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures) prior to using this diagnostic procedure.
2. Review «Strategy Based Diagnosis»(/gmc/sierra/ii-2006-2014/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures__strategy-based-diagnosis) for an overview of the diagnostic approach.
3. «Diagnostic Procedure Instructions»(/gmc/sierra/ii-2006-2014/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures__diagnostic-procedure-instructions) provide an overview of each diagnostic category.

The engine control module (ECM) enables the appropriate fuel injector pulse for each cylinder. The ignition voltage is supplied directly to the fuel injectors. The ECM controls each fuel injector by grounding the control circuit via a solid state device called a driver. A fuel injector coil winding resistance that is too high or too low will affect the engine driveability. A fuel injector control circuit DTC may not set, but a misfire may be apparent. The fuel injector coil windings are affected by temperature. The resistance of the fuel injector coil windings will increase as the temperature of the fuel injector increases.

When performing the fuel injector balance test, the scan tool is first used to energize the fuel pump relay. The fuel injector tester or the scan tool is then used to pulse each injector for a precise amount of time, allowing a measured amount of the fuel to be injected. This causes a drop in the system fuel pressure that can be recorded and used to compare each injector.

1. Monitoring the misfire current counters, or misfire graph, may help to isolate the fuel injector that is causing the condition.
2. Operating the vehicle over a wide temperature range may help isolate the fuel injector that is causing the condition.
3. Perform the fuel injector coil test within the conditions of the customer's concern. A fuel injector condition may only be apparent at a certain temperature, or under certain conditions.

Schematic Reference

Engine Controls Schematics

Connector End View Reference

Component Connector End Views

Electrical Information Reference

1. «Circuit Testing»(/gmc/sierra/ii-2006-2014/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__circuit-testing)
2. «Connector Repairs»(/gmc/sierra/ii-2006-2014/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__connector-repairs)
3. «Testing for Intermittent Conditions and Poor Connections»(/gmc/sierra/ii-2006-2014/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__testing-for-intermittent-conditions-and-poor)
4. «Wiring Repairs»(/gmc/sierra/ii-2006-2014/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__wiring-repairs)

DTC Type Reference

Powertrain Diagnostic Trouble Code (DTC) Type Definitions

Scan Tool Reference

Control Module References for scan tool information

Special Tools

1. CH-48027 Digital Pressure Gauge. See «Special Tools»(/gmc/sierra/ii-2006-2014/remont/testing-diagnostics/#engine-control-system-fuel-system-43l-special-tools-and-equipment) .
2. J 39021 Fuel Injector Coil and Balance Tester
3. J 39021-210 Injector Tester Adapter Box. See «Special Tools»(/gmc/sierra/ii-2006-2014/remont/testing-diagnostics/#engine-control-system-fuel-system-43l-special-tools-and-equipment) .
4. J 39021-301 V-6 Fuel Injector Test Adapter
5. J 44602 Injector Test Adapter. See «Special Tools»(/gmc/sierra/ii-2006-2014/remont/testing-diagnostics/#engine-control-system-fuel-system-43l-special-tools-and-equipment) .

Fuel Injector Coil Test

Verify the resistance of each fuel injector with one of the following methods

1. If the engine coolant temperature (ECT) sensor is between 10-32°C (50-90°F), the resistance of each fuel injector should be 11-14 ohms. If the injectors measure OK, perform the Fuel Injector Balance Test - Fuel Pressure Test. If not within the specified range, replace the fuel injector.
2. If the ECT sensor is not between 10-32°C (50-90°F), measure and record the resistance of each fuel injector with a DMM. Subtract the lowest resistance value from the highest resistance value. The difference between the lowest value and the highest value should be equal to or less than 3 ohms. If the difference is equal to or less than 3 ohms, refer to Fuel Injector Balance Test - Fuel Pressure Test for further diagnosis of the fuel injectors. If the difference is more than 3 ohms, add all of the fuel injector resistance values to obtain a total resistance value. Divide the total resistance value by the number of fuel injectors to obtain an average resistance value. Subtract the lowest individual fuel injector resistance value from the average resistance value. Compute the difference between the highest individual fuel injector resistance value and the average resistance value. Replace the fuel injector that displays the greatest difference above or below the average.

Fuel Injector Balance Test-Fuel Pressure Test

1. Install a CH-48027 . See «Special Tools»(/gmc/sierra/ii-2006-2014/remont/testing-diagnostics/#engine-control-system-fuel-system-43l-special-tools-and-equipment) . Refer to «Fuel Pressure Gauge Installation and Removal»(/gmc/sierra/ii-2006-2014/remont/testing-diagnostics/#engine-control-system-fuel-system-43l-repair-instructions) .
2. Turn ON the ignition, with the engine OFF.
3. Command the fuel pump relay ON with a scan tool.
4. Observe the fuel pressure gauge with the fuel pump commanded ON. The fuel pressure should be 345-414 kPa (50-60 psi). If the fuel pressure is not 345-414 kPa (50-60 psi), refer to «Fuel System Diagnosis»(/gmc/sierra/ii-2006-2014/remont/testing-diagnostics/#engine-control-system-fuel-system-43l-troubleshooting-and-diagnosis) .
5. Monitor the CH-48027 for one minute. See «Special Tools»(/gmc/sierra/ii-2006-2014/remont/testing-diagnostics/#engine-control-system-fuel-system-43l-special-tools-and-equipment) . The fuel pressure should not decrease more than 34 kPa (5 psi). If the fuel pressure decreases more than 34 kPa (5 psi), refer to «Fuel System Diagnosis»(/gmc/sierra/ii-2006-2014/remont/testing-diagnostics/#engine-control-system-fuel-system-43l-troubleshooting-and-diagnosis) .
6. Perform the Fuel Injector Balance Test with Special Tool or the Fuel Injector Balance Test with Tech 2.

Fuel Injector Balance Test with Special Tool

1. Set the amperage supply selector switch on the fuel injector tester to the Balance Test 0.5-2.5 amp position.
2. Connect the J 39021 , J 39021-210 , and the J 39021-301 to the fuel meter body. See «Special Tools»(/gmc/sierra/ii-2006-2014/remont/testing-diagnostics/#engine-control-system-fuel-system-43l-special-tools-and-equipment) .
3. Command the fuel pump relay ON and then OFF three times with a scan tool. On the last command, as the fuel pressure begins to slowly degrade and stabilize, select a fuel pressure within 34 kPa (5 psi) of the maximum pump pressure. Record this fuel pressure. This is the starting pressure at which you will pulse each injector.
4. Command the fuel pump relay ON one more time and energize the fuel injector by depressing the Push to Start Test button on the J 39021 at the previously selected pressure.
5. After the injector stops pulsing, select Min from the Display Mode and record the Min pressure.
6. Clear the Min/Max results.
7. Select Normal from the Display Mode.
8. Repeat steps 2 and 4 through 7 for each fuel injector.
9. Perform the Pressure Drop Calculation.

Fuel Injector Balance Test with Tech 2

1. Command the fuel pump relay ON and then OFF three times with a scan tool. On the last command, as the fuel pressure begins to slowly degrade and stabilize, select a fuel pressure within 34 kPa (5 psi) of the maximum pump pressure. Record this fuel pressure. This is the starting pressure at which you will pulse each injector.
2. With a scan tool, select the Fuel Injector Balance Test function within the Special Functions menu.
3. Select an injector to be tested.
4. Press Enter to prime the fuel system.
5. Energize the fuel injector by depressing the Pulse Injector button on the scan tool at the previously selected pressure.
6. After the injector stops pulsing, select Min from the Display Mode on the CH-48027 and record the Min pressure. See «Special Tools»(/gmc/sierra/ii-2006-2014/remont/testing-diagnostics/#engine-control-system-fuel-system-43l-special-tools-and-equipment) .
7. Clear the Min/Max results on the CH-48027 . See «Special Tools»(/gmc/sierra/ii-2006-2014/remont/testing-diagnostics/#engine-control-system-fuel-system-43l-special-tools-and-equipment) .
8. Select Normal from the Display Mode on the CH-48027 . See «Special Tools»(/gmc/sierra/ii-2006-2014/remont/testing-diagnostics/#engine-control-system-fuel-system-43l-special-tools-and-equipment) .
9. Press Enter on the scan tool to bring you back to the Select Injector screen.
10. Repeat steps 3 through 9 for each fuel injector.
11. Perform the Pressure Drop Calculation.

Pressure Drop Calculation

1. Subtract the minimum pressure from the starting pressure for one fuel injector. The result is the pressure drop value.
2. Obtain a pressure drop value for each fuel injector.
3. Add all of the individual pressure drop values except for the injector suspected of being faulty. This is the total pressure drop.
4. Divide the total pressure drop by the number of fuel injectors that were added together. This is the average pressure drop. The difference between any individual pressure drop and the average pressure drop should not be more than 20 kPa (3 psi). If the difference between any individual pressure drop and the average pressure drop is more than 20 kPa (3 psi), replace the fuel injector, E-85 only. All other engine, refer to «Fuel Injector Cleaning»(/gmc/sierra/ii-2006-2014/remont/testing-diagnostics/#engine-control-system-fuel-system-43l-repair-instructions__fuel-injector-cleaning) .

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

Fuel Injector Replacement

1. Perform the «Diagnostic System Check - Vehicle»(/gmc/sierra/ii-2006-2014/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures) prior to using this diagnostic procedure.
2. Review «Strategy Based Diagnosis»(/gmc/sierra/ii-2006-2014/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures__strategy-based-diagnosis) for an overview of the diagnostic approach.
3. «Diagnostic Procedure Instructions»(/gmc/sierra/ii-2006-2014/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures__diagnostic-procedure-instructions) provide an overview of each diagnostic category.

The engine control module (ECM) enables the appropriate fuel injector pulse for each cylinder. The ignition voltage is supplied directly to the fuel injectors. The ECM controls each fuel injector by grounding the control circuit via a solid state device called a driver. A fuel injector coil winding resistance that is too high or too low will affect the engine driveability. A fuel injector control circuit DTC may not set, but a misfire may be apparent. The fuel injector coil windings are affected by temperature. The resistance of the fuel injector coil windings will increase as the temperature of the fuel injector increases.

The CH-47976 , is used to test the fuel pump, fuel system leak down, and the fuel injectors. See Special Tools . Following the User Guide, CH 47976-11, and the on screen prompts or selections, will indicate the steps required to perform each of the available tests. The tester will perform all of the tests automatically and display results of the test. The results can also be down loaded for storage and printing.

Schematic Reference

Engine Controls Schematics

Connector End View Reference

Component Connector End Views

Electrical Information Reference

1. «Circuit Testing»(/gmc/sierra/ii-2006-2014/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__circuit-testing)
2. «Connector Repairs»(/gmc/sierra/ii-2006-2014/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__connector-repairs)
3. «Testing for Intermittent Conditions and Poor Connections»(/gmc/sierra/ii-2006-2014/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__testing-for-intermittent-conditions-and-poor)
4. «Wiring Repairs»(/gmc/sierra/ii-2006-2014/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__wiring-repairs)

Special Tools

CH-47976 Active Fuel Injector Tester. See Special Tools .

Verify the resistance of each fuel injector with one of the following methods

1. If the engine coolant temperature (ECT) sensor is between 10-32°C (50-90°F), the resistance of each fuel injector should be 11-14 ohms. If the injectors measure OK, perform the Active Fuel Injector Tester (AFIT) Test Procedure. If not within the specified range, replace the fuel injector.
2. If the ECT sensor is not between 10-32°C (50-90°F), measure and record the resistance of each fuel injector with a DMM. Subtract the lowest resistance value from the highest resistance value. The difference between the lowest value and the highest value should be equal to or less than 3 ohms. If the difference is equal to or less than 3 ohms, refer to AFIT Test Procedure. If the difference is more than 3 ohms, add all of the fuel injector resistance values to obtain a total resistance value. Divide the total resistance value by the number of fuel injectors to obtain an average resistance value. Subtract the lowest individual fuel injector resistance value from the average resistance value. Compute the difference between the highest individual fuel injector resistance value and the average resistance value. Replace the fuel injector that displays the greatest difference above or below the average.

AFIT Test Procedure

1. Turn OFF all accessories.
2. Turn OFF the ignition.
3. Install the AFIT. Refer to the AFIT User Guide.
4. Turn ON the AFIT and select the vehicle.
5. Turn ON the ignition and perform the Injector Test. If the AFIT aborts testing due to fuel pressure or fuel leak down, refer to «Fuel System Diagnosis»(/gmc/sierra/ii-2006-2014/remont/testing-diagnostics/#engine-control-system-fuel-system-43l-troubleshooting-and-diagnosis) .
6. View the test results. If any injector exceeds the recommended tolerance, replace the injector(s), E-85 only. All other engine, refer to «Fuel Injector Cleaning»(/gmc/sierra/ii-2006-2014/remont/testing-diagnostics/#engine-control-system-fuel-system-43l-repair-instructions__fuel-injector-cleaning) .

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

Fuel Injector Replacement

1. Perform the «Diagnostic System Check - Vehicle»(/gmc/sierra/ii-2006-2014/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures) prior to using this diagnostic procedure.
2. Review «Strategy Based Diagnosis»(/gmc/sierra/ii-2006-2014/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures__strategy-based-diagnosis) for an overview of the diagnostic approach.
3. «Diagnostic Procedure Instructions»(/gmc/sierra/ii-2006-2014/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures__diagnostic-procedure-instructions) provides an overview of each diagnostic category.

Diagnostic Fault Information

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

The following conditions may cause the fuel pump fuse to open

1. The fuse is faulty.
2. There is an intermittent short to ground in the supply voltage circuit of the fuel pump.
3. The fuel pump has an intermittent internal condition.

Schematic Reference

Engine Controls Schematics

Connector End View Reference

Component Connector End Views

Electrical Information Reference

1. «Circuit Testing»(/gmc/sierra/ii-2006-2014/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__circuit-testing)
2. «Connector Repairs»(/gmc/sierra/ii-2006-2014/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__connector-repairs)
3. «Testing for Intermittent Conditions and Poor Connections»(/gmc/sierra/ii-2006-2014/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__testing-for-intermittent-conditions-and-poor)
4. «Wiring Repairs»(/gmc/sierra/ii-2006-2014/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__wiring-repairs)

Scan Tool Reference

Control Module References for scan tool information

Special Tools

J 43244 Relay Puller Pliers. See Special Tools .

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

1. Fuel Pump Relay Ckt. Short Gnd Test Status
2. Fuel Pump Relay Ckt. Open Test Status
3. Fuel Pump Relay Ckt. Short Volts Test Status

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

1. Ignition OFF, disconnect the fuel pump relay.
2. Ignition ON, verify that a test lamp illuminates between the ground circuit terminal and B+. If the test lamp does not illuminate, test the ground circuit for a short to voltage or an open/high resistance.
3. Verify that a test lamp does not illuminate between the ground circuit terminal and the control circuit terminal. If the test lamp illuminates, test the control circuit for a short to voltage. If the circuit tests normal, replace the ECM.
4. Remove the test lamp.
5. Command the fuel pump relay ON with a scan tool. Verify the scan tool fuel pump relay Ckt. Short Grnd Test Status parameter is OK. If not the specified value, test the fuel pump relay control circuit for a short to ground. If the circuit tests normal, replace the ECM.
6. Install a 3A fused jumper wire between the fuel pump relay control circuit terminal and the ground circuit terminal. Command the fuel pump ON with a scan tool. Verify the scan tool fuel pump relay Ckt. Short Grnd Test Status parameter is Fault. If not the specified value, test the fuel pump relay control circuit for an open/high resistance. If the circuit tests normal, replace the ECM.
7. Inspect the fuel pump fuse. If the fuel pump fuse is open, test for the following conditions: A short to ground in the relay switch B+ circuit A short to ground in the supply voltage circuit of the fuel pump If the above circuits test normal, replace the fuel tank module.
8. Verify that a test light illuminates between the B+ circuit and ground. If the test lamp does not illuminate, test the B+ circuit for an open/high resistance.
9. Connect a 15 A fused jumper wire between the B+ circuit and the supply voltage circuit of the fuel pump. Verify the fuel pup is activated. If the fuel pump does not activate, test for the following conditions: An open/high resistance in the supply voltage circuit of the fuel pump An open/high resistance in the ground circuit of the fuel pump If the above circuits test normal, replace the fuel tank module.
10. If all circuits test normal, test or replace the fuel pump relay.

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

1. «Fuel Sender Assembly Replacement (Regular Cab w/26 Gal Tank)»(/gmc/sierra/ii-2006-2014/remont/testing-diagnostics/#engine-control-system-fuel-system-43l-repair-instructions) or «Fuel Sender Assembly Replacement (Regular Cab w/34 Gal Tank)»(/gmc/sierra/ii-2006-2014/remont/testing-diagnostics/#engine-control-system-fuel-system-43l-repair-instructions) or «Fuel Sender Assembly Replacement (Extended Cab w/26 Gal Tank)»(/gmc/sierra/ii-2006-2014/remont/testing-diagnostics/#engine-control-system-fuel-system-43l-repair-instructions)
2. «Relay Replacement (Attached to Wire Harness)»(/gmc/sierra/ii-2006-2014/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-repair-instructions) or «Relay Replacement (Within an Electrical Center)»(/gmc/sierra/ii-2006-2014/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-repair-instructions)
3. «Control Module References»(/gmc/sierra/ii-2006-2014/remont/communication-devices/#programming-and-setup-all-systems__control-module-references) for ECM replacement, setup, and programming

1. Perform the «Diagnostic System Check - Vehicle»(/gmc/sierra/ii-2006-2014/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures) prior to using this diagnostic procedure.
2. Review «Strategy Based Diagnosis»(/gmc/sierra/ii-2006-2014/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures__strategy-based-diagnosis) for an overview of the diagnostic approach.
3. «Diagnostic Procedure Instructions»(/gmc/sierra/ii-2006-2014/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures__diagnostic-procedure-instructions) provides an overview of each diagnostic category.

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

The fuel system is a returnless on-demand design. The fuel pressure regulator is a part of the fuel pump module, eliminating the need for a return pipe from the engine. A returnless fuel system reduces the internal temperature of the fuel tank by not returning hot fuel from the engine to the fuel tank. Reducing the internal temperature of the fuel tank results in lower evaporative emissions.

The fuel tank stores the fuel supply. An electric turbine style fuel pump attaches to the fuel pump module inside the fuel tank. The fuel pump supplies high pressure fuel through the fuel filter and the fuel feed pipe to the fuel injection system. The fuel pump provides fuel at a higher rate of flow than is needed by the fuel injection system. The fuel pump also supplies fuel to a venturi pump located on the bottom of the fuel pump module. The function of the venturi pump is to fill the fuel pump module reservoir. The fuel pressure regulator, a part of the fuel pump module, maintains the correct fuel pressure to the fuel injection system. The fuel pump module contains a reverse flow check valve. The check valve and the fuel pressure regulator maintain fuel pressure in the fuel feed pipe and the fuel rail in order to prevent long cranking times.

Description and Operation

Fuel System Description

Electrical Information Reference

1. «Circuit Testing»(/gmc/sierra/ii-2006-2014/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__circuit-testing)
2. «Connector Repairs»(/gmc/sierra/ii-2006-2014/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__connector-repairs)
3. «Testing for Intermittent Conditions and Poor Connections»(/gmc/sierra/ii-2006-2014/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__testing-for-intermittent-conditions-and-poor)
4. «Wiring Repairs»(/gmc/sierra/ii-2006-2014/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__wiring-repairs)

Scan Tool Reference

Control Module References for scan tool information

Special Tools

1. CH-48027 Digital Pressure Gauge. See «Special Tools»(/gmc/sierra/ii-2006-2014/remont/testing-diagnostics/#engine-control-system-fuel-system-43l-special-tools-and-equipment) .
2. J 37287 Fuel Line Shut-off Adapter. See «Special Tools»(/gmc/sierra/ii-2006-2014/remont/testing-diagnostics/#engine-control-system-fuel-system-43l-special-tools-and-equipment) .

1. Ignition ON, engine OFF, command the fuel pump relay ON with a scan tool. You should hear the fuel pump turn ON and OFF. If the fuel pump does not operate, refer to «Fuel System Diagnosis»(/gmc/sierra/ii-2006-2014/remont/testing-diagnostics/#engine-control-system-fuel-system-43l-troubleshooting-and-diagnosis) .
2. Ignition OFF, all accessories OFF, install a CH-48027 . See «Special Tools»(/gmc/sierra/ii-2006-2014/remont/testing-diagnostics/#engine-control-system-fuel-system-43l-special-tools-and-equipment) . Refer to «Fuel Pressure Gauge Installation and Removal»(/gmc/sierra/ii-2006-2014/remont/testing-diagnostics/#engine-control-system-fuel-system-43l-repair-instructions) .
3. Ignition ON, engine OFF, command the fuel pump relay ON with a scan tool. Verify the fuel pressure is between 345-414 kPa (50-60 psi) and does not decrease more than 34 kPa (5 psi) in 1 minute.

1. Ignition ON, engine OFF, command the fuel pump relay ON with a scan tool and observe the fuel pressure gauge while the fuel pump is operating. Verify the fuel pressure is between 345-414 kPa (50-60 psi). If the fuel pressure is greater than the specified range, replace the fuel pump module. If the fuel pressure is less than the specified range, test, inspect, and repair the items listed below. If all items test normal, replace the fuel pump module. Restricted fuel feed pipe Inspect the harness connectors and the ground circuits of the fuel pump for poor connections.
2. Verify that the fuel pressure does not decrease more than 34 kPa (5 psi) in 1 minute. If the fuel pressure decreases more than the specified value, perform the following procedure: Ignition OFF, relieve the fuel pressure. Refer to «Fuel Pressure Relief (CH-48027)»(/gmc/sierra/ii-2006-2014/remont/testing-diagnostics/#engine-control-system-fuel-system-43l-repair-instructions__fuel-pressure-relief-ch-48027) . Install the J 37287 between the fuel feed pipe and the fuel rail. See «Special Tools»(/gmc/sierra/ii-2006-2014/remont/testing-diagnostics/#engine-control-system-fuel-system-43l-special-tools-and-equipment) . Open the valve on the J 37287 . See «Special Tools»(/gmc/sierra/ii-2006-2014/remont/testing-diagnostics/#engine-control-system-fuel-system-43l-special-tools-and-equipment) . Ignition ON, command the fuel pump relay ON with a scan tool and bleed the air from the CH-48027 . See «Special Tools»(/gmc/sierra/ii-2006-2014/remont/testing-diagnostics/#engine-control-system-fuel-system-43l-special-tools-and-equipment) . Command the fuel pump relay ON and then OFF with a scan tool. Close the valve on the J 37287 . See «Special Tools»(/gmc/sierra/ii-2006-2014/remont/testing-diagnostics/#engine-control-system-fuel-system-43l-special-tools-and-equipment) . Monitor the fuel pressure for 1 minute. If the fuel pressure decreases more than 34 kPa (5 psi) within the specified time, locate and replace the leaking fuel injector(s). If the fuel pressure does not decrease more than 34 kPa (5 psi) within the specified time, replace the fuel pump module.
3. Relieve the fuel pressure to 69 kPa (10 psi). Verify that the fuel pressure does not decrease more than 14 kPa (2 psi) in 5 minutes. If the fuel pressure decreases more than the specified value, replace the fuel pump module.
4. Operate the vehicle within the conditions of the customer's concern while monitoring the fuel pressure with the CH-48027 . See «Special Tools»(/gmc/sierra/ii-2006-2014/remont/testing-diagnostics/#engine-control-system-fuel-system-43l-special-tools-and-equipment) . The fuel pressure should not drop off during acceleration, cruise or hard cornering. If the fuel pressure drops off, test, inspect, and repair the items listed below. If all items test normal, replace the fuel pump module. Restricted fuel feed pipe Inspect the harness connectors and the ground circuits of the fuel pump for poor connections
5. If the fuel system tests normal, refer to «Symptoms - Engine Controls»(/gmc/sierra/ii-2006-2014/remont/testing-diagnostics/#engine-control-system-fuel-system-43l-troubleshooting-and-diagnosis) .

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

1. «Fuel Line Replacement - Chassis (Regular Cab)»(/gmc/sierra/ii-2006-2014/remont/testing-diagnostics/#engine-control-system-fuel-system-43l-repair-instructions) or «Fuel Line Replacement - Chassis (Extended Cab)»(/gmc/sierra/ii-2006-2014/remont/testing-diagnostics/#engine-control-system-fuel-system-43l-repair-instructions) or «Fuel Line Replacement - Chassis (Extended Cab - w/8 Ft Bed)»(/gmc/sierra/ii-2006-2014/remont/testing-diagnostics/#engine-control-system-fuel-system-43l-repair-instructions)
2. «Fuel Injector Replacement»(/gmc/sierra/ii-2006-2014/remont/testing-diagnostics/#engine-control-system-fuel-system-43l-repair-instructions)
3. «Fuel Sender Assembly Replacement (Regular Cab w/26 Gal Tank)»(/gmc/sierra/ii-2006-2014/remont/testing-diagnostics/#engine-control-system-fuel-system-43l-repair-instructions) or «Fuel Sender Assembly Replacement (Regular Cab w/34 Gal Tank)»(/gmc/sierra/ii-2006-2014/remont/testing-diagnostics/#engine-control-system-fuel-system-43l-repair-instructions) or «Fuel Sender Assembly Replacement (Extended Cab w/26 Gal Tank)»(/gmc/sierra/ii-2006-2014/remont/testing-diagnostics/#engine-control-system-fuel-system-43l-repair-instructions)

Description

Water contamination in the fuel system may cause driveability conditions such as hesitation, stalling, no start, or misfires in one or more cylinders. Water may collect near a single fuel injector at the lowest point in the fuel injection system, and cause a misfire in that cylinder. If the fuel system is contaminated with water, inspect the fuel system components for rust, or deterioration.

Alcohol concentrations of 10 percent or greater in fuel can be detrimental to fuel system components. Alcohol contamination may cause fuel system corrosion, deterioration of rubber components, and subsequent fuel filter restriction. Some types of alcohol are more detrimental to fuel system components than others. Ethanol is commonly used in gasoline, but in concentrations of no more than 10 percent. Some fuels, such as E85, contain a very high percentage of ethanol. Fuel with more than 10 percent ethanol may cause driveability conditions such as hesitation, lack of power, stalling, or no start.

Alcohol in Fuel Testing Procedure

The fuel sample should be drawn from the bottom of the tank so that any water present in the tank will be detected. The sample should be bright and clear. If alcohol contamination is suspected then use the following procedure to test the fuel quality.

1. Using a 100 ml (3.4 oz) specified cylinder with 1 ml (0.03 oz) graduation marks, fill the cylinder with fuel to the 90 ml (3.04 oz) mark.
2. Add 10 ml (0.34 oz) of water in order to bring the total fluid volume to 100 ml (3.4 oz) and install a stopper.
3. Shake the cylinder vigorously for 10-15 seconds.
4. Carefully loosen the stopper in order to release the pressure.
5. Re-install the stopper and shake the cylinder vigorously again for 10-15 seconds.
6. Put the cylinder on a level surface for approximately 5 minutes in order to allow adequate liquid separation.

If alcohol is present in the fuel, the volume of the lower layer, which would now contain both alcohol and water, will be more than 10 ml (0.34 oz). For example, if the volume of the lower layer is increased to 15 ml (0.51 oz), this indicates at least 5 percent alcohol in the fuel. The actual amount of alcohol may be somewhat more because this procedure does not extract all of the alcohol from the fuel.

Particulate Contaminants in Fuel Testing Procedure

The fuel sample should be drawn from the bottom of the tank so that any water present in the tank will be detected. The sample should be bright and clear. If the sample appears cloudy, or contaminated with water, as indicated by a water layer at the bottom of the sample, use the following procedure to diagnose the fuel.

1. Using an approved fuel container, draw approximately 0.5 liter (0.13 gal) of fuel.
2. Place the cylinder on a level surface for approximately 5 minutes in order to allow settling of the particulate contamination.

Particulate contamination will show up in various shapes and colors. Sand will typically be identified by a white or light brown crystals. Rubber will appear as black and irregular particles. If particles are found clean the entire fuel system thoroughly.

Water contamination in the fuel system may cause driveability conditions such as hesitation, stalling, no start, or misfires in one or more cylinders. Water may collect near a single fuel injector at the lowest point in the fuel injection system, and cause a misfire in that cylinder. If the fuel system is contaminated with water, inspect the fuel system components for rust or deterioration.

Ethanol concentrations of greater than 10 percent can cause driveability conditions and fuel system deterioration. Fuel with more than 10 percent ethanol could result in driveability conditions such as hesitation, lack of power, stalling, or no start. Excessive concentrations of ethanol used in vehicles not designed for it may cause fuel system corrosion, deterioration of rubber components, and fuel filter restriction.

Test Procedure

1. Test the fuel composition using J 44175 Fuel Composition Tester and J44175-3 Instruction Manual. See «Special Tools»(/gmc/sierra/ii-2006-2014/remont/testing-diagnostics/#engine-control-system-fuel-system-43l-special-tools-and-equipment) .
2. Subtract 50 from the reading on the DMM in order to obtain the percentage of alcohol in the fuel sample. Refer to the examples in the Fuel Composition Test Examples table.
3. If the fuel sample contains more than 15 percent ethanol, add fresh, regular gasoline to the vehicle's fuel tank.
4. Test the fuel composition.
5. If testing shows the ethanol percentage is still more than 15 percent, replace the fuel in the vehicle.

Fuel Composition Test Examples

1. Perform the «Diagnostic System Check - Vehicle»(/gmc/sierra/ii-2006-2014/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures) prior to using this diagnostic procedure.
2. Review «Strategy Based Diagnosis»(/gmc/sierra/ii-2006-2014/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures__strategy-based-diagnosis) for an overview of the diagnostic approach.
3. «Diagnostic Procedure Instructions»(/gmc/sierra/ii-2006-2014/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures__diagnostic-procedure-instructions) provides an overview of each diagnostic category.

There are 3 dual-tower ignition coils that are part of the ignition control module (ICM). The ICM contains coil driver circuits that command the coils to operate. The ICM has the following circuits

1. An ignition voltage circuit
2. A ground
3. An ignition control (IC) 1 control circuit for the 1-4 ignition coil
4. An IC 2 control circuit for the 2-5 ignition coil
5. An IC 3 control circuit for the 3-6 ignition coil
6. A low reference circuit

The engine control module (ECM) controls each dual-tower ignition coil by transmitting timing pulses on the ignition coil control circuit to the ICM for the proper coil to enable a spark event.

Inspect the spark plug wires for proper orientation.

Schematic Reference

Engine Controls Schematics

Connector End View Reference

Component Connector End Views

Electrical Information Reference

1. «Circuit Testing»(/gmc/sierra/ii-2006-2014/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__circuit-testing)
2. «Connector Repairs»(/gmc/sierra/ii-2006-2014/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__connector-repairs)
3. «Testing for Intermittent Conditions and Poor Connections»(/gmc/sierra/ii-2006-2014/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__testing-for-intermittent-conditions-and-poor)
4. «Wiring Repairs»(/gmc/sierra/ii-2006-2014/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__wiring-repairs)

Scan Tool Reference

Control Module References for scan tool information

Special Tools

1. J 26792 Spark Tester. See «Special Tools»(/gmc/sierra/ii-2006-2014/remont/testing-diagnostics/#engine-control-system-fuel-system-43l-special-tools-and-equipment) .
2. J 43244 Relay Puller Pliers. See «Special Tools»(/gmc/sierra/ii-2006-2014/remont/testing-diagnostics/#engine-control-system-fuel-system-43l-special-tools-and-equipment) .

1. With the ignition OFF, remove the fuel pump relay using the J 43244 . See «Special Tools»(/gmc/sierra/ii-2006-2014/remont/testing-diagnostics/#engine-control-system-fuel-system-43l-special-tools-and-equipment) .
2. Crank the engine and test for a spark on each cylinder spark plug wire using the J 26792 . See «Special Tools»(/gmc/sierra/ii-2006-2014/remont/testing-diagnostics/#engine-control-system-fuel-system-43l-special-tools-and-equipment) . Ground the companion cylinder spark plug wire of each cylinder when it is tested. If a bright blue spark is present on all 6 of the cylinders, remove and inspect all of the spark plugs for proper torque, proper gap, wear, damage, and fouling. Refer to «Spark Plug Replacement»(/gmc/sierra/ii-2006-2014/remont/testing-diagnostics/#engine-control-system-fuel-system-43l-repair-instructions) and «Spark Plug Inspection»(/gmc/sierra/ii-2006-2014/remont/testing-diagnostics/#engine-control-system-fuel-system-43l-repair-instructions__spark-plug-inspection) . Replace the spark plugs if necessary. If there is no spark on any of the cylinders, test the ignition voltage circuit of the ICM for an open/high resistance or short to ground, or test the ground circuit of the ICM for an open/high resistance, or a faulty ICM. The wire circuit resistance should measure less than 3 ohms. If spark is present on one or more of the cylinders, inspect and test the spark plug wires for arching, cuts, rubbing on other components, and proper resistance, refer to «Spark Plug Wire Inspection»(/gmc/sierra/ii-2006-2014/remont/testing-diagnostics/#engine-control-system-fuel-system-43l-repair-instructions__spark-plug-wire-inspection) or a faulty ICM. If all tests are normal, then the system is operating correctly.

Component Testing

1. With positive polarity to the low reference terminal, measure for 9,000-11,000 ohms at 20-23°C (68-74°F) room temperature between each of the ignition coil control terminals and the low reference terminal of the ICM. If the resistance is not within the specified range, replace the ICM.
2. Measure for 7,000-15,000 ohms at 20-23°C (68-74°F) room temperature between each pair of coil towers on the ICM. If the resistance is not within the specified range, replace the ICM.

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

1. «Ignition Coil Replacement»(/gmc/sierra/ii-2006-2014/remont/testing-diagnostics/#engine-control-system-fuel-system-43l-repair-instructions)
2. «Spark Plug Replacement»(/gmc/sierra/ii-2006-2014/remont/testing-diagnostics/#engine-control-system-fuel-system-43l-repair-instructions)
3. «Spark Plug Wire Replacement»(/gmc/sierra/ii-2006-2014/remont/testing-diagnostics/#engine-control-system-fuel-system-43l-repair-instructions)

Operating Instructions for the Evaporative Emission System Tester (EEST)

Vehicle Setup

1. Engine OFF, open the hood. Position a large fan to blow air under the vehicle onto the fuel tank area.
2. Connect the red battery clip from the tester to the positive battery terminal.
3. Connect the black battery clip from the tester to chassis ground.

Flowmeter Test - Leak Detection

1. Open the Nitrogen tank valve and turn the NITROGEN/SMOKE valve on the front control panel to NITROGEN.
2. Connect the hose to the correct test orifice on the bottom front of the tester. For orifice size, refer to the GM Service manual for the vehicle being tested. The vehicle specific information can be found in service procedures for DTCs that relate to evaporative emission (EVAP) system leaks.
3. Press and release the remote switch to activate the tester.
4. Position the sliding red flag on the flowmeter to align with the floating indicator. When the red flag is set, press and release the remote switch to deactivate the tester.
5. Remove the hose from the test orifice and install the hose onto the vehicle. For proper connection location, and the special tool numbers for any adapters that may be required, refer to the service procedures for DTCs that relate to EVAP system leaks.
6. Ignition ON, seal the EVAP system per instructions in the service procedures for DTCs that relate to EVAP system leaks. Most systems can be sealed using a scan tool output control for the EVAP canister vent solenoid valve, other systems require that the vent system be plugged.
7. Press and release the remote switch to activate the nitrogen flow and fill the system.
8. Compare the stable floating indicator position to the red flag. ABOVE the red flag, the result is UNACCEPTABLE, FAIL-Go to Smoke Procedure BELOW the red flag, the result is ACCEPTABLE, PASS-Test complete
9. Press and release the remote switch to deactivate the tester.

Smoke Procedure - Locate the Leak

1. Turn OFF any fans that may cause air movement around or near the vehicle.
2. Connect the nitrogen/smoke hose to the vehicle as directed in the service procedures. Some vehicles require that the nitrogen/smoke hose be connected at the front of the EVAP system at the EVAP service port. An adapter may be necessary. Other vehicles require the connection be made at the rear of the system using an adapter at the fuel fill cap. Consult the service procedures for DTCs that relate to evaporative emission (EVAP) system leaks for vehicle specific instructions regarding connection location and adapters.
3. Open the nitrogen tank valve and turn the NITROGEN/SMOKE valve on the control panel to SMOKE.
4. Press and release the remote switch to activate the tester and inject smoke into the EVAP system.
5. Verify smoke has filled the EVAP system by opening the system opposite the end where smoke is injected. When injecting smoke at the service port, remove the fuel fill cap, or temporarily leave the EVAP canister vent valve open, until smoke is observed. Then close the system and continue testing. If using a special tool fuel fill cap adapter at the filler neck, vent the system at the service port until smoke is observed then close the system to continue with the test.
6. Press and release the remote switch to deactivate the tester.
7. Introduce smoke into the system for an additional 60 seconds. Continue introducing smoke at 15-second intervals, as necessary.
8. Using the a high-intensity white light, inspect the entire EVAP system path, and look for the source of the leak indicated by the exiting smoke. Introduce smoke at 15-second intervals, as needed, until leak source is identified.

The Concern

Ideal circumstances for conducting the EVAP Flowmeter Test require equal temperatures between the nitrogen gas and the vehicle EVAP system. Significant differences in temperature between them can result in a flow or pressure change during testing, causing misleading results. Typically, the Evaporative Emissions System Tester is stored indoors, approximately 21°C (70°F). Vehicles brought in for diagnosis may have an EVAP system at significantly different temperatures -40 to +43°C (-40 to +110°F).

For Example

Note. With no temperature difference between the nitrogen gas and EVAP system, the resulting vehicle EVAP system pressure will remain stable at 13 inches H2O once pressurized, providing no leaks are present.

When the EVAP Flowmeter Tests are performed with significant differences in temperature between the nitrogen gas and the vehicle EVAP system, the following results can occur

1. An increase in flow during the flowmeter test can be caused by a vehicle's warm EVAP system cooling down.
2. A decrease in flow during the flowmeter test can be caused by a vehicle's cool EVAP system warming up.

The Solution

When working on a vehicle with significant temperature differences between the vehicle EVAP system and the nitrogen gas, allow the vehicle EVAP system temperature to stabilize as close as possible to the temperature of the nitrogen gas before conducting the Flowmeter Test.

1. Perform the «Diagnostic System Check - Vehicle»(/gmc/sierra/ii-2006-2014/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures) prior to using this diagnostic procedure.
2. Review «Strategy Based Diagnosis»(/gmc/sierra/ii-2006-2014/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures__strategy-based-diagnosis) for an overview of the diagnostic approach.
3. «Diagnostic Procedure Instructions»(/gmc/sierra/ii-2006-2014/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures__diagnostic-procedure-instructions) provides an overview of each diagnostic category.

Several states require that a vehicle pass on-board diagnostic (OBD) system tests and the inspection/maintenance (I/M) emission inspection in order to renew license plates. This is accomplished by viewing the I/M System Status display on a scan tool. Using a scan tool, the technician can observe the I/M System Status in order to verify that the vehicle meets the criteria that comply with the local area requirements.

Conditions for Updating the I/M System Status

Each system monitor requires at least one, and sometimes several diagnostic tests. The result of each test is reported by a diagnostic trouble code (DTC). A system monitor is complete when either all of the DTCs composing the monitor have Run and Passed, or when any one of the DTCs comprising the monitor has illuminated the malfunction indicator lamp (MIL). Once the system monitor is complete, the I/M System Status display will indicate YES in the Completed column.

For example, when the HO2S Heater Status indicates YES, either all of the oxygen sensor heater tests have passed or one of the tests has illuminated the MIL. If the vehicle has 4 heated oxygen sensors, either all 4 heater circuit tests have passed or one of the heater circuit tests has illuminated the MIL. The I/M System Status will indicate NO under the Completed column when any of the required tests for that system have not run. The following is a list of conditions that would set the I/M System Status indicator to NO

1. The vehicle is new from the factory and has not yet been driven through the necessary drive conditions to complete the tests.
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.

Monitored Emission Control Systems

The OBD II System monitors all emission control systems that are on-board. The OBD II regulations require monitoring of the following

1. The air conditioning system
2. The catalytic converter efficiency
3. Comprehensive component monitoring-Emission related inputs and outputs
4. The evaporative emission (EVAP) system
5. The fuel delivery system
6. Heated catalyst monitoring
7. Misfire monitoring
8. The oxygen sensor system (O2S or HO2S)
9. The oxygen sensor heater system (HO2S heater)

For the specific DTCs required for each system, refer to Inspection/Maintenance (I/M) Test DTC Table . Systems such as fuel delivery, misfire, and comprehensive components may not be listed in a system status list. These tests run continuously and do not require an I/M System Status indicator.

Review the I/M System Status indicators. All I/M System Status indicators should report YES.

1. Observe the Engine DTC information with a scan tool. If a DTC is set that would prevent the I/M System Status tests from completing, diagnose that DTC before continuing. Refer to «Inspection/Maintenance (I/M) Test DTC Table»(/gmc/sierra/ii-2006-2014/remont/testing-diagnostics/#engine-control-system-fuel-system-43l-troubleshooting-and-diagnosis__inspectionmaintenance-im-test-dtc-table) .
2. Review applicable service bulletins for software updates that would prevent the I/M System Status tests from completing. If a control module re-program or other repair is required, perform the «Inspection/Maintenance Complete System Set Procedure»(/gmc/sierra/ii-2006-2014/remont/testing-diagnostics/#engine-control-system-fuel-system-43l-troubleshooting-and-diagnosis) .
3. Observe the I/M System Status indicators. If any I/M System Status indicators report NO, perform the «Inspection/Maintenance Complete System Set Procedure»(/gmc/sierra/ii-2006-2014/remont/testing-diagnostics/#engine-control-system-fuel-system-43l-troubleshooting-and-diagnosis) .

1. Perform the «Diagnostic System Check - Vehicle»(/gmc/sierra/ii-2006-2014/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures) prior to using this diagnostic procedure.
2. Review «Strategy Based Diagnosis»(/gmc/sierra/ii-2006-2014/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures__strategy-based-diagnosis) for an overview of the diagnostic approach.
3. «Diagnostic Procedure Instructions»(/gmc/sierra/ii-2006-2014/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures__diagnostic-procedure-instructions) provide an overview of each diagnostic category.

The purpose of the Inspection/Maintenance (I/M) complete system set procedure is to satisfy the enable criteria necessary to execute all of the I/M readiness diagnostics and complete the drive cycles for those particular diagnostics. When all I/M monitored diagnostic tests are completed, the I/M System Status indicators are set to YES. Perform the I/M Complete System Set Procedure if any I/M System Status indicators are set to NO.

I/M Data List

To determine if the I/M readiness diagnostic tests can be run this ignition cycle, use a scan tool to observe the I/M monitor enabled parameters in the I/M Data List.

Conditions for Meeting a Cold Start

1. The ignition voltage between 11-18 volts.
2. The barometric pressure (BARO) is more than 75 kPa.
3. The start-up engine coolant temperature (ECT) is between 4-30°C (39-86°F).
4. The start-up intake air temperature (IAT) is between 4-30°C (39-86°F).
5. The difference between the IAT and the ECT is 6°C (10.8°F).
6. The ambient air temperature is between 4-30°C (39-86°F).
7. Fuel level is between 15-85 percent
8. Without RPO LMG-The fuel alcohol content is less than 15 percent.
9. With RPO LMG-The fuel alcohol content is less than 87 percent.

Review the Inspection/Maintenance (I/M) System Status indicators with a scan tool. All I/M System Status indicators should report YES.

Inspection/Maintenance (I/M) System Set Procedure

1. Ensure that the vehicle meets the conditions for a cold start listed above. If the evaporative emission (EVAP) I/M System Status indicator displays NO, perform the EVAP Service bay test if available. If the EVAP Service bay test is NOT available, it may take up to 6 drive cycles, with up to 17 hours between drive cycles, for the EVAP I/M System Status indicator to transition to YES. If the O2S Heater System Status indicator displays NO, ensure that the ignition has been turned OFF for at least 10 hours.
2. Set the vehicle parking brake and ensure the vehicle is in Park for automatic transmission or Neutral for manual transmission.
3. Turn OFF all accessories; HVAC system, other electrical loads, including aftermarket/add-on equipment, etc.
4. Start and idle the engine for at least 2 minutes and until 65°C (149°F) is achieved.
5. Run the engine for 6.5 minutes within the following conditions: MAF parameter between 4-30 g/s Engine speed steady between 1000-3000 RPM
6. Return the engine to idle for 1 minute.
7. Apply and hold brake pedal, and shift to Drive for automatic, or apply clutch pedal for manual and operate the vehicle within the following conditions for 2 minutes: Depress the accelerator pedal until TP Sensor angle is more than 2 percent. MAF signal between 15-30 g/s RPM steady between 1200-2000 RPM
8. Release the accelerator pedal and shift the vehicle to Park for automatic, or Neutral and release clutch pedal for manual, and allow the engine to idle for 2 minutes.
9. Quickly depress the accelerator pedal until TP Sensor Angle is more than 8 percent and return to idle, repeat 3 times.
10. Allow engine to idle for at least 2 minutes.
11. Release the parking brake and drive vehicle at 24 km/h (15 mph) or slower for 2 minutes.
12. Continue to drive the vehicle for at least 5.5 miles between 45-112 km/h (28-70 mph) with the vehicle reaching at least 80 km/h (50 mph).
13. Release the accelerator pedal for at least 2 seconds. This will allow the vehicle to enter decel fuel cut-off.
14. Depress the accelerator pedal until the TP Sensor angle is increased 3-20 percent and maintain a safe speed for 1 minute.
15. Safely stop the vehicle, with the engine in drive for automatic or in neutral with the clutch pedal depressed and parking brake applied for manual, idle for 2 minutes.
16. Shift to Park for automatic and apply the parking brake, or Neutral and release clutch pedal for manual.
17. Turn OFF the ignition and exit the vehicle. Do NOT disturb the vehicle for 45 minutes.
18. Observe the Inspection/Maintenance (I/M) System Status with a scan tool. All of the I/M System Status indicators should display YES. If the EVAP I/M System Status indicator displays NO turn OFF the ignition for 17 hours, ensure that the vehicle meets the conditions for a cold start, and repeat steps 12-18 six more times, or until the EVAP I/M System Status indicator transitions to YES. If the indicator continues to display NO, refer to the «Inspection/Maintenance (I/M) Test DTC Table»(/gmc/sierra/ii-2006-2014/remont/testing-diagnostics/#engine-control-system-fuel-system-43l-troubleshooting-and-diagnosis__inspectionmaintenance-im-test-dtc-table) to identify the DTCs that did not run. Follow the Conditions for Running the DTC in order to set the EVAP I/M System Status indicator If any of the I/M System Status indicators display NO, refer to the «Inspection/Maintenance (I/M) Test DTC Table»(/gmc/sierra/ii-2006-2014/remont/testing-diagnostics/#engine-control-system-fuel-system-43l-troubleshooting-and-diagnosis__inspectionmaintenance-im-test-dtc-table) for the indicator which did not display YES. The I/M System DTC Table identifies the DTCs associated with each I/M System Status Indicator. Follow the Conditions for Running the DTC in order to set the associated status indicator.
19. Observe the engine DTC information with a scan tool. Verify no DTCs are present. If a DTC is set, diagnose using the «Diagnostic Trouble Code (DTC) List - Vehicle»(/gmc/sierra/ii-2006-2014/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures__diagnostic-trouble-code-dtc-list) . After repairs, perform the «Inspection/Maintenance Complete System Set Procedure»(/gmc/sierra/ii-2006-2014/remont/testing-diagnostics/#engine-control-system-fuel-system-43l-troubleshooting-and-diagnosis) to verify no further DTCs are set.

Inspection/Maintenance (I/M) Test DTC Table

1. Perform the «Diagnostic System Check - Vehicle»(/gmc/sierra/ii-2006-2014/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures) prior to using this diagnostic procedure.
2. Review «Strategy Based Diagnosis»(/gmc/sierra/ii-2006-2014/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures__strategy-based-diagnosis) for an overview of the diagnostic approach.
3. «Diagnostic Procedure Instructions»(/gmc/sierra/ii-2006-2014/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures__diagnostic-procedure-instructions) provides an overview of each diagnostic category.

The purpose of the evaporative emission (EVAP) Service Bay Test is to aid in resetting the EVAP inspection/maintenance system status. For this vehicle that is equipped with the engine off natural vacuum diagnostic, the Service Bay Test uses the scan tool to initiate the engine control module (ECM) regular sequence of EVAP system DTC tests, but with different enable criteria. By using the Service Bay Test the inspection/maintenance indicator can be set without the need for multiple cold soaks.

The scan tool displays for the Service Bay Test are based on the events that occur within the following three categories

1. The engine running portion of the tests-The vehicle must remain at rest, in Park, or in Neutral, during this portion of the test. This test inspects for large leaks, a leaking purge valve and/or vent system restrictions. The scan tool will display test progress or the reason for an abort or failure.
2. Drive cycle-The scan tool will display time and distance needed to warm the fuel.
3. Ignition OFF-During this portion of the test, the engine controller will remain active for up to 45 minutes when the ignition is turned OFF to allow control of the EVAP canister vent valve and run the engine off natural vacuum test. The engine controller inspects for small leaks during this period by monitoring fuel tank pressure or vacuum. If the system is sealed, there will be a pressure or vacuum change. Pressure or vacuum changes that are less than the calibrated values indicate a leak.

When the EVAP diagnostics are initiated by the Service Bay Test, the scan tool will indicate if the enable conditions listed below are not met, or will display a specific reason if the test aborts. When complete, the display will indicate that the tests passed or failed.

Conditions for Running the Test

The following conditions must be met in order to enable the Service Bay Test

1. The battery voltage is between 11-18V.
2. The engine coolant temperature (ECT) is less than 35°C (95°F) at start-up.
3. The EVAP inspection/maintenance system status indicator is set to NO.
4. The fuel level is 15-85 percent capacity and cannot be refueled during the tests.
5. There are no DTCs displayed.
6. The vehicle must be driven for the time and distance specified on the scan tool.
7. The ambient air temperature is between 0-40°C (32-104°F).
8. The ignition must remain OFF during the engine OFF portion of the test, and the vehicle must remain at rest.

Note. If the Service Bay Test aborts or fails, a DTC will NOT be set.

1. Install a scan tool.
2. Select the Service Bay Test with the scan tool.
3. Follow the instructions on the scan tool. If the test aborts, correct the condition for running the test, then retest. If the test fails, repair the vehicle for the condition indicated by the failure message on the scan tool.
4. Verify that the EVAP inspection/maintenance system status is set to YES.

See also:
• Diagnostic System Check - Vehicle
• Strategy Based Diagnosis
• Diagnostic Procedure Instructions
• Wiring Repairs
• Spark Plug Inspection
• Loss of Coolant
• Symptoms - Engine Mechanical
• Heated Oxygen and Oxygen Sensor Caution
• Mass Airflow Sensor with Intake Air Temperature Sensor Replacement
• Symptoms - Engine Exhaust
• Thermostat Diagnosis
• Cooling System Draining and Filling (Vac-N-Fill)
• Cooling System Draining and Filling (Static Fill)
• Temperature Versus Resistance
• DTC P0106
• DTC P0106
• Fuel System Description
• Instrument Cluster Schematics
• Engine Controls Schematics
• Component Connector End Views
• Circuit Testing
• Connector Repairs
• Testing for Intermittent Conditions and Poor Connections
• Control Module References
• Diagnostic Repair Verification
• Battery Inspection/Test
• Engine Cranks Slowly
• Electrical Center Identification Views
• Diagnostic Trouble Code (DTC) List - Vehicle
• DTC P0685, P0689, or P0690
• Fuel System Diagnosis (Without FPCM)
• Restricted Exhaust
• Special Tools
• Fuel Injector Cleaning
• Relay Replacement (Attached to Wire Harness)
• Fuel Pressure Relief (CH-48027)
• Spark Plug Wire Inspection
• Road Test Warning
• Fuel System Diagnosis
• Inspection/Maintenance (I/M) Test DTC Table