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Engine Controls and Fuel - 3.9l - Troubleshooting & Diagnosis Chevrolet Impala IX

Testing & Diagnostics ~13397 words

Diagnostic Instructions

  1. Perform the «Diagnostic System Check - Vehicle»(/chevrolet/impala/ix-2006-2016/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures) prior to using this diagnostic procedure.
  2. Review «Strategy Based Diagnosis»(/chevrolet/impala/ix-2006-2016/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»(/chevrolet/impala/ix-2006-2016/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures__diagnostic-procedure-instructions) provides 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/impala/ix-2006-2016/remont/communication-devices/#programming-and-setup-all-systems__control-module-references) .
  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 «Testing for Intermittent Conditions and Poor Connections»(/chevrolet/impala/ix-2006-2016/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures) .
  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 the fuel system for the following: The fuel system for correct operation volume and pressure-Refer «Fuel System Diagnosis»(/chevrolet/impala/ix-2006-2016/remont/testing-diagnostics/#engine-controls-and-fuel-39l-troubleshooting-diagnosis) . The fuel injectors for proper operation-Refer to «Fuel Injector Diagnosis (J39021 or Tech 2)»(/chevrolet/impala/ix-2006-2016/remont/testing-diagnostics/#engine-controls-and-fuel-39l-troubleshooting-diagnosis) or «Fuel Injector Diagnosis (CH47976)»(/chevrolet/impala/ix-2006-2016/remont/testing-diagnostics/#engine-controls-and-fuel-39l-troubleshooting-diagnosis) . The fuel quality condition-Refer to «Alcohol/Contaminants-in-Fuel Diagnosis»(/chevrolet/impala/ix-2006-2016/remont/testing-diagnostics/#engine-controls-and-fuel-39l-troubleshooting-diagnosis) .
  2. Test ignition system for the following: Proper ignition system operation-Refer to «Electronic Ignition System Diagnosis»(/chevrolet/impala/ix-2006-2016/remont/testing-diagnostics/#engine-controls-and-fuel-39l-troubleshooting-diagnosis) . Spark plugs-Refer to «Spark Plug Inspection»(/chevrolet/impala/ix-2006-2016/remont/testing-diagnostics/#engine-controls-and-fuel-39l-repair-instructions__spark-plug-inspection) . Spark plugs for correct application-Refer to «Ignition System Specifications»(/chevrolet/impala/ix-2006-2016/remont/testing-diagnostics/#engine-controls-and-fuel-39l-specifications__ignition-system-specifications) .
  3. Inspect for the following conditions The proper operation of the transmission torque converter clutch (TCC)-The scan tool should indicate an engine speed drop when the TCC is commanded ON. Refer to «Torque Converter Diagnosis»(/chevrolet/impala/ix-2006-2016/remont/automatic-trans/#automatic-transmission-4t65-e-symptom-troubleshooting-diagnosis__torque-converter-diagnosis) . The proper operation of the A/C compressor Items that can cause an engine to run lean or rich-Refer to «DTC P0171 or P0172»(/chevrolet/impala/ix-2006-2016/remont/testing-diagnostics/#engine-controls-and-fuel-39l-dtc-p0010-through-dtc-p0340) . The crankshaft position sensor for proper operation The proper operation of the knock sensor (KS) system Inspect the exhaust system-Refer to «Symptoms - Engine Exhaust»(/chevrolet/impala/ix-2006-2016/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 The proper operation of the evaporative emission (EVAP) canister purge solenoid The proper operation of the engine cooling system-Refer to «Symptoms - Engine Cooling»(/chevrolet/impala/ix-2006-2016/remont/cooling-system-mechanical/#engine-cooling-system) .
  4. Inspect the engine for the following mechanical failures: Refer to «Symptoms - Engine Mechanical»(/chevrolet/impala/ix-2006-2016/remont/mechanical/#engine-mechanical-39l-diagnostic-information-and-procedures) . Excessive oil in the combustion chamber or leaking valve seals Oil Consumption 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
  5. If the above conditions do not address the symptom, refer to the additional symptoms tests.

Hard Start

  1. Verify that the engine coolant temperature (ECT) has not shifted in value. Refer to «Temperature Versus Resistance»(/chevrolet/impala/ix-2006-2016/remont/testing-diagnostics/#engine-controls-and-fuel-35l-specifications__temperature-versus-resistance) .
  2. Verify the engine electrical system for correct operation. Refer to «Symptoms - Engine Electrical»(/chevrolet/impala/ix-2006-2016/remont/charging-system/#battery-charging-system-and-starting-system__symptoms-engine-electrical) .
  3. Verify that the driver is using the correct starting procedure as described in the owners manual.
  4. Verify that there is adequate fuel.
  5. Inspect for excessive crankshaft endplay that will cause the crankshaft position sensor reluctor wheel to move out of alignment with the crankshaft position sensor. Refer to «Crankshaft and Bearing Cleaning and Inspection»(/chevrolet/impala/ix-2006-2016/remont/mechanical/#engine-mechanical-39l-repair-instructions-off-vehicle-1-of-3) .
  6. Start and run the vehicle until fully arm. Observe the camshaft position variation parameter while accelerating up to 1,500 RPM and back to idle several times. The camshaft position variation should indicate a value for 1-2 s, then return to 0 degree. If the camshaft actuator does not respond, refer to «Camshaft Position Actuator Cleaning and Inspection»(/chevrolet/impala/ix-2006-2016/remont/mechanical/#engine-mechanical-35l-repair-instructions-off-vehicle-2-of-3__camshaft-position-actuator-cleaning-and-inspection) and «Camshaft Position Actuator Magnet Cleaning and Inspection»(/chevrolet/impala/ix-2006-2016/remont/mechanical/#engine-mechanical-35l-repair-instructions-off-vehicle-1-of-3__camshaft-position-actuator-magnet-cleaning-and) .

Hesitation, Sag, Stumble

  1. Inspect the mass air flow (MAF) sensor for obstruction, contamination, and damage. Refer to «Mass Airflow Sensor with Intake Air Temperature Sensor Replacement»(/chevrolet/impala/ix-2006-2016/remont/testing-diagnostics/#engine-controls-and-fuel-35l-repair-instructions) .
  2. Test the generator. Refer to «Symptoms - Engine Electrical»(/chevrolet/impala/ix-2006-2016/remont/charging-system/#battery-charging-system-and-starting-system__symptoms-engine-electrical) . Repair the charging system if the generator output voltage is less than 9 V or more than 16 V.
  3. Inspect for excessive crankshaft endplay that will cause the crankshaft position sensor reluctor wheel to move out of alignment with the crankshaft position sensor. Refer to «Crankshaft and Bearing Cleaning and Inspection»(/chevrolet/impala/ix-2006-2016/remont/mechanical/#engine-mechanical-39l-repair-instructions-off-vehicle-1-of-3) .

Poor Fuel Economy

  1. Heavy loads being carried or towed
  2. Acceleration rate too much or too often
  3. Inspect the brake system for brake drag.
  4. Inspect for incorrect operation of the speedometer.
  5. Verify that the engine coolant temperature (ECT) has not shifted in value. Refer to «Temperature Versus Resistance»(/chevrolet/impala/ix-2006-2016/remont/testing-diagnostics/#engine-controls-and-fuel-35l-specifications__temperature-versus-resistance) .
  6. Inspect the mass air flow (MAF) sensor for obstruction, contamination, and damage. Refer to «Mass Airflow Sensor with Intake Air Temperature Sensor Replacement»(/chevrolet/impala/ix-2006-2016/remont/testing-diagnostics/#engine-controls-and-fuel-35l-repair-instructions) .
  7. 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.
  8. Start and run the vehicle until fully warm. Observe the camshaft position variation parameter while accelerating up to 1,500 RPM and back to idle several times. The camshaft position variation should indicate a value for 1-2 s, then return to 0 degree. If the camshaft actuator responds erratic, inconsistent, or not at all, refer to «Camshaft Position Actuator Magnet Cleaning and Inspection»(/chevrolet/impala/ix-2006-2016/remont/mechanical/#engine-mechanical-35l-repair-instructions-off-vehicle-1-of-3__camshaft-position-actuator-magnet-cleaning-and) and «Camshaft Position Actuator Cleaning and Inspection»(/chevrolet/impala/ix-2006-2016/remont/mechanical/#engine-mechanical-35l-repair-instructions-off-vehicle-2-of-3__camshaft-position-actuator-cleaning-and-inspection) .

Detonation/Spark Knock

  1. Test for an engine overheating condition. Refer to «Symptoms - Engine Cooling»(/chevrolet/impala/ix-2006-2016/remont/cooling-system-mechanical/#engine-cooling-system) .
  2. Verify that the engine coolant temperature (ECT) has not shifted in value. Refer to «Temperature Versus Resistance»(/chevrolet/impala/ix-2006-2016/remont/testing-diagnostics/#engine-controls-and-fuel-35l-specifications__temperature-versus-resistance) .
  3. If there are no engine mechanical faults, fill the fuel tank with a known high quality fuel that meets the vehicle minimum octane requirements.

Lack of Power, Hesitation, or Cut Out

  1. Inspect the engine electrical system for correct operation. Refer to «Symptoms - Engine Electrical»(/chevrolet/impala/ix-2006-2016/remont/charging-system/#battery-charging-system-and-starting-system__symptoms-engine-electrical) .
  2. Verify that each injector harness is connected to the correct injector.
  3. Inspect the mass air flow (MAF) sensor for obstruction, contamination, and damage. Refer to «Mass Airflow Sensor with Intake Air Temperature Sensor Replacement»(/chevrolet/impala/ix-2006-2016/remont/testing-diagnostics/#engine-controls-and-fuel-35l-repair-instructions) .
  4. Start and run the vehicle until fully warm. Observe the camshaft position variation parameter while accelerating up to 1,500 RPM and back to idle several times. The camshaft position variation should indicate a value for 1-2 s, then return to 0 degree. If the camshaft actuator does not respond, refer to «Camshaft Position Actuator Magnet Cleaning and Inspection»(/chevrolet/impala/ix-2006-2016/remont/mechanical/#engine-mechanical-35l-repair-instructions-off-vehicle-1-of-3__camshaft-position-actuator-magnet-cleaning-and) and «Camshaft Position Actuator Cleaning and Inspection»(/chevrolet/impala/ix-2006-2016/remont/mechanical/#engine-mechanical-35l-repair-instructions-off-vehicle-2-of-3__camshaft-position-actuator-cleaning-and-inspection) .

Rough, Unstable, or Incorrect Idle and Stalling

  1. Inspect the mass air flow (MAF) sensor for obstruction, contamination, and damage. Refer to «Mass Airflow Sensor with Intake Air Temperature Sensor Replacement»(/chevrolet/impala/ix-2006-2016/remont/testing-diagnostics/#engine-controls-and-fuel-35l-repair-instructions) .
  2. Inspect the engine mounts. Refer to «Engine Mount Inspection»(/chevrolet/impala/ix-2006-2016/remont/mechanical/#engine-mechanical-39l-repair-instructions-on-vehicle__engine-mount-inspection) .
  3. Inspect the intake and exhaust manifolds for casting flash.

Surges/Chuggles

  1. Inspect the mass air flow (MAF) sensor for obstruction, contamination, and damage. Refer to «Mass Airflow Sensor with Intake Air Temperature Sensor Replacement»(/chevrolet/impala/ix-2006-2016/remont/testing-diagnostics/#engine-controls-and-fuel-35l-repair-instructions) .
  2. Test the heated oxygen sensors (HO2S). The HO2S should respond quickly to a change in throttle position. If the HO2S do not respond to different throttle positions, inspect for contamination from fuel, silicon, or the incorrect use of RTV sealant. The sensors may have a white powdery coating and result in a high, but false, signal voltage, which gives a rich exhaust indication. The ECM reduces the amount of fuel delivered to the engine, causing a driveability condition.
  3. Verify that each injector harness is connected to the correct injector.
  4. Start and run the vehicle until fully warm. Observe the camshaft position variation parameter while accelerating up to 1,500 RPM and back to idle several times. The camshaft position variation should indicate a value for 1-2 s, then return to 0 degree. If the camshaft actuator does not respond, refer to «Camshaft Position Actuator Magnet Cleaning and Inspection»(/chevrolet/impala/ix-2006-2016/remont/mechanical/#engine-mechanical-35l-repair-instructions-off-vehicle-1-of-3__camshaft-position-actuator-magnet-cleaning-and) and «Camshaft Position Actuator Cleaning and Inspection»(/chevrolet/impala/ix-2006-2016/remont/mechanical/#engine-mechanical-35l-repair-instructions-off-vehicle-2-of-3__camshaft-position-actuator-cleaning-and-inspection) .

Poor Fuel Fill Quality

ProblemCauses
DEFINITION: During the fueling process a continual, occasional or no fuel nozzle shut-off condition has occurred.
Difficult to fillFuel fill limiter vent valve stuck closed Evaporative emission (EVAP) canister restricted EVAP vent valve stuck closed Hose between canister and canister vent solenoid twisted or kinked if applicable High fuel temperature Fuel filler hose is kinked Faulty dispensing nozzle Ignition switch ON, vent valve closed
Over fillFill limiter vent valve stuck open or leaking Fuel inlet check valve stuck open
Pre-mature shut-off of the fuel dispensing nozzle occurs immediately after engaging dispensing nozzle, tank emptyRestricted vapor lines or fuel fill pipe High fuel temperature Inlet check valve at tank stuck closed, fill pipe full of fuel Fuel tank full, gauge not accurate
Pre-mature shut-off of the fuel dispensing nozzle, more than 1/8 of tank capacity dispensedKinked, pinched or plugged lines in fuel tank vent system EVAP vent valve stuck closed or restricted EVAP canister restricted Fuel limiting vent valve stuck closed or obstruction at top of fuel tank
Fuel SpitbackRestricted EVAP canister High fuel temperature Ignition switch ON, EVAP vent valve closed
  1. Perform the «Diagnostic System Check - Vehicle»(/chevrolet/impala/ix-2006-2016/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures) prior to using this diagnostic procedure.
  2. Review «Strategy Based Diagnosis»(/chevrolet/impala/ix-2006-2016/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»(/chevrolet/impala/ix-2006-2016/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures__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

If the condition is intermittent, move the related harnesses and connectors with the engine operating. Monitor the scan tool Circuit Test Status parameters for the component. The Circuit Test Status parameter will change from OK or Not Run to Fault if there is a condition with the circuit or a connection.

Reference Information

Schematic Reference

  1. «Instrument Cluster Schematics»(/chevrolet/impala/ix-2006-2016/remont/gauges-instrument-panels/#instrument-panel-system-displays-and-gauges)
  2. «Engine Controls Schematics»(/chevrolet/impala/ix-2006-2016/remont/testing-diagnostics/#engine-controls-and-fuel-39l-wiring-schematic-diagrams)

Connector End View Reference

Electrical Information Reference

  1. «Circuit Testing»(/chevrolet/impala/ix-2006-2016/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__circuit-testing)
  2. «Connector Repairs»(/chevrolet/impala/ix-2006-2016/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__connector-repairs)
  3. «Testing for Intermittent Conditions and Poor Connections»(/chevrolet/impala/ix-2006-2016/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures)
  4. «Wiring Repairs»(/chevrolet/impala/ix-2006-2016/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

  1. Ignition ON, command the MIL ON and OFF with a scan tool. The MIL should turn ON and OFF as commanded.
  2. Command the MIL ON and OFF with a scan tool while observing the following control circuit status parameters: MIL Ckt Short Gnd Test Status MIL Ckt Open Test Status MIL Ckt Short Volts Test Status Each parameter should change from OK to Not Run or from Not Run to OK.
  3. Operate the vehicle within the Conditions for Running the DTC to verify that the DTC does not reset. You may also operate the vehicle within the conditions that you observed from the Freeze Frame/Failure Records data.

Circuit/System Testing

  1. Ignition 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 X1 harness connector. Ignition ON, the MIL should not illuminate. If the MIL is illuminated, test the MIL control circuit terminal 68 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 68 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/connections test normal, replace the ECM. Ignition ON, verify that the IPC warning indicators are illuminated.

Repair Procedures

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

  1. «Instrument Cluster Replacement»(/chevrolet/impala/ix-2006-2016/remont/gauges-instrument-panels/#instrument-panel-system-displays-and-gauges)
  2. «Control Module References»(/chevrolet/impala/ix-2006-2016/remont/communication-devices/#programming-and-setup-all-systems__control-module-references) for ECM replacement, setup, and programming
  1. Perform the «Diagnostic System Check - Vehicle»(/chevrolet/impala/ix-2006-2016/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures) prior to using this diagnostic procedure.
  2. Review «Strategy Based Diagnosis»(/chevrolet/impala/ix-2006-2016/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»(/chevrolet/impala/ix-2006-2016/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures__diagnostic-procedure-instructions) provides an overview of each diagnostic category.

This Engine Cranks but Does Not Run is an organized approach to identify a condition which causes the engine to crank but not start. This diagnostic directs the technician to the appropriate system diagnosis.

This diagnostic assumes the system voltage levels are adequate for starter motor operation. Fuel level and fuel quality must be determined for correct diagnosis.

Schematic Reference

Connector End View Reference

Electrical Information Reference

  1. «Battery Inspection/Test»(/chevrolet/impala/ix-2006-2016/remont/charging-system/#battery-charging-system-and-starting-system)
  2. «Circuit Testing»(/chevrolet/impala/ix-2006-2016/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__circuit-testing)
  3. «Connector Repairs»(/chevrolet/impala/ix-2006-2016/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__connector-repairs)
  4. «Engine Cranks Slowly»(/chevrolet/impala/ix-2006-2016/remont/charging-system/#battery-charging-system-and-starting-system__engine-cranks-slowly)
  5. «Starting System Description and Operation»(/chevrolet/impala/ix-2006-2016/remont/charging-system/#battery-charging-system-and-starting-system__starting-system-description-and-operation)
  6. «Testing for Intermittent Conditions and Poor Connections»(/chevrolet/impala/ix-2006-2016/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures)
  7. «Wiring Repairs»(/chevrolet/impala/ix-2006-2016/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__wiring-repairs)

DTC Type Reference

Scan Tool Reference

Control Module References for scan tool information

Special Tools

  1. CH 48027: Digital Pressure Gauge
  2. CH 48027-100: Digital Pressure Gauge
  3. J 26792: HEI Spark Tester

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

  1. Crank the engine while observing the scan tool Vehicle DTC Information. If any of the following DTCs are set, refer to «Diagnostic Trouble Code (DTC) List - Vehicle»(/chevrolet/impala/ix-2006-2016/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures__diagnostic-trouble-code-dtc-list) to diagnose those DTCs: P0016, P0201-P0206, P0230, P0335, P0336, P0351-P0353, P0601, P0602, P0603, P0604, P0606, P0607, P060D, P062F, P0685, P0690, P1516, P1682, P2610.
  2. Ignition OFF for 90 seconds, determine the current vehicle testing altitude. Ignition ON, observe the scan tool MAP Sensor parameter. Compare the parameter to the «Altitude Versus Barometric Pressure»(/chevrolet/impala/ix-2006-2016/remont/testing-diagnostics/#engine-controls-and-fuel-35l-specifications__altitude-versus-barometric-pressure) table. The MAP Sensor Pressure parameter should be within the specified range indicated in the table. If the reading is not correct for your altitude, diagnose the MAP sensor. Refer to «DTC P0106»(/chevrolet/impala/ix-2006-2016/remont/testing-diagnostics/#engine-controls-and-fuel-39l-dtc-p0010-through-dtc-p0340) .
  3. Verify the following scan tool parameters indicate OK when the engine is cranked: Cylinder 1-6 Injector Circuit Short to Ground Test Status Cylinder 1-6 Injector Circuit Open Test Status If the parameters do not indicate the specified values, refer to «DTC P0201, P0202, P0203, P0204, P0205, or P0206»(/chevrolet/impala/ix-2006-2016/remont/testing-diagnostics/#engine-controls-and-fuel-39l-dtc-p0010-through-dtc-p0340) .
  4. Verify the following scan tool parameters change from NOT RUN to OK, when the engine is cranked: Cylinder 1-6 Injector Circuit Short to Volts Test Status If the parameters do not indicate the specified values, refer to «DTC P0201, P0202, P0203, P0204, P0205, or P0206»(/chevrolet/impala/ix-2006-2016/remont/testing-diagnostics/#engine-controls-and-fuel-39l-dtc-p0010-through-dtc-p0340) .
  5. Crank the engine while observing the scan tool engine speed parameter. If engine RPM is not indicated, refer to «DTC P0335»(/chevrolet/impala/ix-2006-2016/remont/testing-diagnostics/#engine-controls-and-fuel-39l-dtc-p0010-through-dtc-p0340) .
  6. Install a J 26792: Spark Tester
  7. Crank the engine while observing the spark tester. The spark tester should spark. If spark is not observed refer to «Electronic Ignition System Diagnosis»(/chevrolet/impala/ix-2006-2016/remont/testing-diagnostics/#engine-controls-and-fuel-39l-troubleshooting-diagnosis) .
  8. With the ignition ON and the engine OFF, test the fuses that are supplied by the powertrain relay for voltage. If the test lamp does not illuminate on at least one side of each fuse, refer to «DTC P0685, P0689, P0690, or P1682»(/chevrolet/impala/ix-2006-2016/remont/testing-diagnostics/#engine-controls-and-fuel-39l-dtc-p0341-through-dtc-p2544) .
  9. Command the fuel pump ON and OFF. Fuel pump should energize when commanded ON and De-energize when commanded OFF. If the fuel pump does not respond refer to «Fuel Pump Electrical Circuit Diagnosis»(/chevrolet/impala/ix-2006-2016/remont/testing-diagnostics/#engine-controls-and-fuel-39l-troubleshooting-diagnosis) .
  10. Turn OFF the ignition.
  11. Install the CH 48027: Gauge or CH 48027-100: Gauge. Turn ON the ignition and command the fuel pump ON while observing the CH 48027-100: Gauge. The fuel pressure should be between 384-425 kPa (56-62 psi). If the fuel pressure is not within 384-425 kPa (56-62 psi) refer to «Fuel System Diagnosis»(/chevrolet/impala/ix-2006-2016/remont/testing-diagnostics/#engine-controls-and-fuel-39l-troubleshooting-diagnosis) .
  12. Inspect for the following conditions: Compare the actual engine coolant temperature to the ECT parameter. Air filter and air intake system for restrictions and obstructions Test the fuel for ethanol content. Refer to «Fuel Composition Diagnosis»(/chevrolet/impala/ix-2006-2016/remont/testing-diagnostics/#engine-controls-and-fuel-39l-troubleshooting-diagnosis) for 3.9L (RPO LGD), VIN code M and E85 compatible engines only. Test the fuel for contamination. Refer to «Alcohol/Contaminants-in-Fuel Diagnosis»(/chevrolet/impala/ix-2006-2016/remont/testing-diagnostics/#engine-controls-and-fuel-39l-troubleshooting-diagnosis) for non-E85 vehicles. Inspect the spark plug and spark plug wires. Refer to «Spark Plug Inspection»(/chevrolet/impala/ix-2006-2016/remont/testing-diagnostics/#engine-controls-and-fuel-39l-repair-instructions__spark-plug-inspection) and «Spark Plug Wire Inspection»(/chevrolet/impala/ix-2006-2016/remont/testing-diagnostics/#engine-controls-and-fuel-39l-repair-instructions__spark-plug-wire-inspection) . Test the exhaust system for restrictions. Refer to «Restricted Exhaust»(/chevrolet/impala/ix-2006-2016/remont/exhaust/#engine-exhaust-system) .

Repair Verification

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

  1. «Spark Plug Replacement»(/chevrolet/impala/ix-2006-2016/remont/testing-diagnostics/#engine-controls-and-fuel-39l-repair-instructions)
  2. «Spark Plug Wire Replacement»(/chevrolet/impala/ix-2006-2016/remont/testing-diagnostics/#engine-controls-and-fuel-39l-repair-instructions)
  1. Perform the «Diagnostic System Check - Vehicle»(/chevrolet/impala/ix-2006-2016/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures) prior to using this diagnostic procedure.
  2. Review «Strategy Based Diagnosis»(/chevrolet/impala/ix-2006-2016/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»(/chevrolet/impala/ix-2006-2016/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures__diagnostic-procedure-instructions) provides an overview of each diagnostic category.

Diagnostic Fault Information

CircuitShort to GroundOpen/High ResistanceShort to VoltageSignal Performance
Battery Voltage - Relay Switch Side12
Fuel Pump Supply Voltage123
Fuel Pump Relay ControlP0230P0230P0230
Fuel Pump Relay Ground2
Fuel Pump Ground2
1 Open fuel pump fuse, cranks no start 2 The engine cranks but does not run. 3 Fuel pump operates continuously, discharges battery

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

Connector End View Reference

  1. «Component Connector End Views -- Index»(/chevrolet/impala/ix-2006-2016/remont/body-electrical/#wiring-systems-and-power-management-component-connector-end-views-index)
  2. «Electrical Center Identification Views»(/chevrolet/impala/ix-2006-2016/remont/electrical-component-locations/#wiring-systems-and-power-management-component-locator-electrical-center-identification-views)

Electrical Information Reference

  1. «Circuit Testing»(/chevrolet/impala/ix-2006-2016/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__circuit-testing)
  2. «Connector Repairs»(/chevrolet/impala/ix-2006-2016/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__connector-repairs)
  3. «Testing for Intermittent Conditions and Poor Connections»(/chevrolet/impala/ix-2006-2016/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures)
  4. «Wiring Repairs»(/chevrolet/impala/ix-2006-2016/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

IMPORTANTAn open or a short to voltage in the control circuit will cause both the Ckt Open Test Status and the Ckt Short Volts Test Status parameters to display Fault.

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 using the J 43244: Pliers.
  2. Ignition ON, verify that a test lamp illuminates between the ground circuit terminal 85 and B+. If the test lamp does not illuminate, test the ground circuit for a short to voltage or an open/high resistance.
  3. Verify that a test lamp does not illuminate between the ground circuit terminal 85 and the control circuit terminal 86. If the test lamp illuminates, test the control circuit for a short to voltage. If the circuit tests normal, replace the 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 Gnd Test Status parameter is OK. If not the specified value, test the fuel pump relay control circuit for a short to ground. If the circuit tests normal, replace the ECM.
  6. Install a 3 A fused jumper wire between the fuel pump relay control circuit terminal 86 and the ground circuit terminal 85. Command the fuel pump relay ON with a scan tool. Verify the scan tool Fuel Pump Relay Ckt Short Gnd Test Status parameter is Fault. If not the specified value, test the fuel pump relay control circuit for an open/high resistance. If the circuit tests normal, replace the 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 terminal 30 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 terminal 30 and the supply voltage circuit terminal 87 of the fuel pump. Verify the fuel pump 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.

Component Testing

  1. Test for 70-110 ohms between terminals 85 and 86. If the resistance is not within the specified range, replace the relay.
  2. Test for infinite resistance between the following terminals: 30 and 86 30 and 87 30 and 85 85 and 87 If not the specified value, replace the relay.
  3. Install a 15 A fused jumper wire between relay terminal 85 and 12 V. Install a jumper wire between relay terminal 86 and ground. Test for less than 2 ohms between terminals 30 and 87. If greater than the specified range, replace the relay.

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

  1. «Fuel Tank Module Replacement»(/chevrolet/impala/ix-2006-2016/remont/testing-diagnostics/#engine-controls-and-fuel-39l-repair-instructions)
  2. «Relay Replacement (Attached to Wire Harness)»(/chevrolet/impala/ix-2006-2016/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-repair-instructions) or «Relay Replacement (Within an Electrical Center)»(/chevrolet/impala/ix-2006-2016/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-repair-instructions)
  3. «Control Module References»(/chevrolet/impala/ix-2006-2016/remont/communication-devices/#programming-and-setup-all-systems__control-module-references) for ECM replacement, setup, and programming
  1. Perform the «Diagnostic System Check - Vehicle»(/chevrolet/impala/ix-2006-2016/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures) prior to using this diagnostic procedure.
  2. Review «Strategy Based Diagnosis»(/chevrolet/impala/ix-2006-2016/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»(/chevrolet/impala/ix-2006-2016/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures__diagnostic-procedure-instructions) provides an overview of each diagnostic category.

The control module enables the fuel pump relay when the ignition switch is turned ON. The control module will disable the fuel pump relay within 2 seconds unless the control module detects ignition reference pulses. The control module continues to enable the fuel pump relay as long as ignition reference pulses are detected. The control module 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 tank 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 tank module inside the fuel tank. The fuel pump supplies high pressure fuel through the fuel filter, contained in the fuel tank module, 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 tank module. The function of the venturi pump is to fill the fuel tank module reservoir. The fuel pressure regulator, a part of the fuel tank module, maintains the correct fuel pressure to the fuel injection system. The fuel tank 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

Electrical Information Reference

  1. «Circuit Testing»(/chevrolet/impala/ix-2006-2016/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__circuit-testing)
  2. «Connector Repairs»(/chevrolet/impala/ix-2006-2016/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__connector-repairs)
  3. «Testing for Intermittent Conditions and Poor Connections»(/chevrolet/impala/ix-2006-2016/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures)
  4. «Wiring Repairs»(/chevrolet/impala/ix-2006-2016/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
  2. J 37287: Fuel Line Shut-off Adapters
  3. J 37287-FF: Fuel Line Shut-off Adapters, if equipped with an LGD engine
IMPORTANTInspect the fuel system for damage or external leaks before proceeding. Verify that adequate fuel is in the fuel tank before proceeding. The fuel pump relay may need to be commanded ON a few times in order to obtain the highest possible fuel pressure. Before proceeding with this test review the User Manual CH 48027-5 for Safety Information and Instructions.
  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 Pump Electrical Circuit Diagnosis»(/chevrolet/impala/ix-2006-2016/remont/testing-diagnostics/#engine-controls-and-fuel-39l-troubleshooting-diagnosis) .
  2. Ignition OFF, all accessories OFF, install a CH 48027: Gauge. Refer to «Fuel Pressure Gauge Installation and Removal»(/chevrolet/impala/ix-2006-2016/remont/testing-diagnostics/#engine-controls-and-fuel-39l-repair-instructions) .
  3. Ignition ON, engine OFF, command the fuel pump relay ON with a scan tool. Verify the fuel pressure is between 386-427 kPa (56-62 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 386-427 kPa (56-62 psi). If the fuel pressure is greater than the specified range, replace the fuel tank 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 tank 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 (Without CH 48027)»(/chevrolet/impala/ix-2006-2016/remont/testing-diagnostics/#engine-controls-and-fuel-35l-repair-instructions__fuel-pressure-relief-without-ch-48027) or «Fuel Pressure Relief (CH 48027)»(/chevrolet/impala/ix-2006-2016/remont/testing-diagnostics/#engine-controls-and-fuel-35l-repair-instructions) . Install the J 37287: Adapter or the J 37287-FF: Adapter between the fuel feed pipe and the fuel rail. Open the valve on the J 37287: Adapter or the J 37287-FF: Adapter. Ignition ON, command the fuel pump relay ON with a scan tool and bleed the air from the CH 48027: Gauge. Command the fuel pump relay ON and then OFF with a scan tool. Close the valve on the J 37287: Adapter or the J 37287-FF: Adapter. 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 tank 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 tank module.
  4. Operate the vehicle within the conditions of the customer's concern while monitoring the fuel pressure with the CH 48027: Gauge. 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 tank 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»(/chevrolet/impala/ix-2006-2016/remont/testing-diagnostics/#engine-controls-and-fuel-39l-troubleshooting-diagnosis) .

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

  1. «Fuel Line Replacement - Chassis»(/chevrolet/impala/ix-2006-2016/remont/testing-diagnostics/#engine-controls-and-fuel-39l-repair-instructions)
  2. «Fuel Injector Replacement»(/chevrolet/impala/ix-2006-2016/remont/testing-diagnostics/#engine-controls-and-fuel-39l-repair-instructions)
  3. «Fuel Tank Module Replacement»(/chevrolet/impala/ix-2006-2016/remont/testing-diagnostics/#engine-controls-and-fuel-39l-repair-instructions)
  1. Perform the «Diagnostic System Check - Vehicle»(/chevrolet/impala/ix-2006-2016/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures) prior to using this diagnostic procedure.
  2. Review «Strategy Based Diagnosis»(/chevrolet/impala/ix-2006-2016/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»(/chevrolet/impala/ix-2006-2016/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures__diagnostic-procedure-instructions) provide an overview of each diagnostic category.

The control module enables the appropriate fuel injector pulse for each cylinder. The ignition voltage is supplied directly to the fuel injectors. The control module 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

Connector End View Reference

  1. «Component Connector End Views -- Index»(/chevrolet/impala/ix-2006-2016/remont/body-electrical/#wiring-systems-and-power-management-component-connector-end-views-index)
  2. «Inline Harness Connector End Views»(/chevrolet/impala/ix-2006-2016/remont/body-electrical/#wiring-systems-and-power-management-inline-harness-connector-end-views)

Electrical Information Reference

  1. «Circuit Testing»(/chevrolet/impala/ix-2006-2016/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__circuit-testing)
  2. «Connector Repairs»(/chevrolet/impala/ix-2006-2016/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__connector-repairs)
  3. «Testing for Intermittent Conditions and Poor Connections»(/chevrolet/impala/ix-2006-2016/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures)
  4. «Wiring Repairs»(/chevrolet/impala/ix-2006-2016/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
  2. J-39021-450 Fuel Injector Harness Adapter
  3. J 39021 Fuel Injector Coil and Balance Tester
  4. J 39021-210 Injector Tester Adapter Box

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.
IMPORTANTDO NOT perform this test if the engine coolant temperature (ECT) is above 94°C (201°F). Irregular fuel pressure readings may result due to hot soak fuel boiling. Verify that adequate fuel is in the fuel tank before proceeding with this diagnostic. Before proceeding with this test review the User Manual CH 48027-5 for Safety Information and Instructions.

Fuel Injector Balance Test-Fuel Pressure Test

  1. Install a fuel pressure gauge. Refer to «Fuel Pressure Gauge Installation and Removal»(/chevrolet/impala/ix-2006-2016/remont/testing-diagnostics/#engine-controls-and-fuel-39l-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 384-425 kPa (56-62 psi). If the fuel pressure is not 384-425 kPa (56-62 psi), refer to «Fuel System Diagnosis»(/chevrolet/impala/ix-2006-2016/remont/testing-diagnostics/#engine-controls-and-fuel-39l-troubleshooting-diagnosis) .
  5. Monitor the fuel pressure gauge for one minute. 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»(/chevrolet/impala/ix-2006-2016/remont/testing-diagnostics/#engine-controls-and-fuel-39l-troubleshooting-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. Disconnect the multi-way harness connector of the fuel injectors.
  3. Connect the J 39021 , the J 39021-210 , and the J-39021-450 to the fuel injector multi-way connector.
  4. 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.
  5. 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.
  6. After the injector stops pulsing, select Min from the Display Mode and record the Min pressure.
  7. Clear the Min/Max results.
  8. Select Normal from the Display Mode.
  9. Repeat steps 5 through 8 for each fuel injector.
  10. 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.
  7. Clear the Min/Max results on the CH-48027 .
  8. Select Normal from the Display Mode on the CH-48027 .
  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.

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

  1. Perform the «Diagnostic System Check - Vehicle»(/chevrolet/impala/ix-2006-2016/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures) prior to using this diagnostic procedure.
  2. Review «Strategy Based Diagnosis»(/chevrolet/impala/ix-2006-2016/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»(/chevrolet/impala/ix-2006-2016/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures__diagnostic-procedure-instructions) provides an overview of each diagnostic category.

The control module enables the appropriate fuel injector pulse for each cylinder. The ignition voltage is supplied directly to the fuel injectors. The control module 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 Active Fuel Injector Tester (AFIT), CH 47976, is used to test the fuel pump, fuel system leak down, and the fuel injectors. 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

Connector End View Reference

  1. «Component Connector End Views -- Index»(/chevrolet/impala/ix-2006-2016/remont/body-electrical/#wiring-systems-and-power-management-component-connector-end-views-index)
  2. «Inline Harness Connector End Views»(/chevrolet/impala/ix-2006-2016/remont/body-electrical/#wiring-systems-and-power-management-inline-harness-connector-end-views)

Electrical Information Reference

  1. «Circuit Testing»(/chevrolet/impala/ix-2006-2016/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__circuit-testing)
  2. «Connector Repairs»(/chevrolet/impala/ix-2006-2016/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__connector-repairs)
  3. «Testing for Intermittent Conditions and Poor Connections»(/chevrolet/impala/ix-2006-2016/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures)
  4. «Wiring Repairs»(/chevrolet/impala/ix-2006-2016/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__wiring-repairs)

Special Tools

CH-47976 Active Fuel Injector Tester

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 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.
IMPORTANTDO NOT perform this test if the engine coolant temperature (ECT) is above 94°C (201°F). Irregular fuel pressure readings may result due to hot soak fuel boiling.
IMPORTANTVerify that adequate fuel is in the fuel tank before proceeding with this diagnostic.

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»(/chevrolet/impala/ix-2006-2016/remont/testing-diagnostics/#engine-controls-and-fuel-39l-troubleshooting-diagnosis) .
  6. View the test results. If any injector exceeds the recommended tolerance, replace the injector(s).

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

  1. Perform the «Diagnostic System Check - Vehicle»(/chevrolet/impala/ix-2006-2016/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures) prior to using this diagnostic procedure.
  2. Review «Strategy Based Diagnosis»(/chevrolet/impala/ix-2006-2016/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»(/chevrolet/impala/ix-2006-2016/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures__diagnostic-procedure-instructions) provides an overview of each diagnostic category.
CircuitShort to GroundOpen/High ResistanceShort to VoltageSignal Performance
Ignition 1 Voltage12
Fuel Injector 1 ControlP0201P0201P0201
Fuel Injector 2 ControlP0202P0202P0202
Fuel Injector 3 ControlP0203P0203P0203
Fuel Injector 4 ControlP0204P0204P0204
Fuel Injector 5 ControlP0205P0205P0205
Fuel Injector 6 ControlP0206P0206P0206
1 Open fuse, cranks no start 2 Open before splice, cranks no start

The engine control module (ECM) enables the appropriate fuel injector pulse for each cylinder. Ignition voltage is supplied to the fuel injectors. The ECM controls each fuel injector by grounding the control circuit via a solid state device called a driver.

Performing the Fuel Injector Solenoid Coil Test may help isolate an intermittent condition. Refer to Fuel Injector Solenoid Coil Test .

Schematic Reference

Connector End View Reference

Electrical Information Reference

  1. «Circuit Testing»(/chevrolet/impala/ix-2006-2016/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__circuit-testing)
  2. «Connector Repairs»(/chevrolet/impala/ix-2006-2016/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__connector-repairs)
  3. «Testing for Intermittent Conditions and Poor Connections»(/chevrolet/impala/ix-2006-2016/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures)
  4. «Wiring Repairs»(/chevrolet/impala/ix-2006-2016/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 35616-200: Test Light Probe Kit

Engine idling, observe the following control circuit status parameters for each fuel injector

  1. Injector Ckt Short Gnd Test Status
  2. Injector Ckt Open Test Status
  3. Injector Ckt Short Volts Test Status Each parameter should toggle between OK and Not Run or Not Run and OK.
  1. Ignition OFF, disconnect the X102 fuel injector multi-way connector.
  2. Ignition ON, verify that the J 35616-200: Test Light illuminates between the ignition circuit terminal A ECM harness side 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, test or replace the fuel injector.
  3. Ignition OFF, connect the J 35616-200: Test Light between the ignition circuit terminal A and the control circuit ECM harness side, of the appropriate injector listed below: Injector 1 terminal C Injector 2 terminal D Injector 3 terminal E Injector 4 terminal F Injector 5 terminal G Injector 6 terminal H
  4. Engine cranking, the test lamp should flash for each injector. If the test lamp is always ON, test the appropriate control circuit for a short to ground. If the circuit tests normal, replace the ECM. If the test lamp is always OFF, test the appropriate control circuit for a short to voltage or an open/high resistance. If the circuit tests normal, replace the ECM.
  5. Ignition OFF, measure for 10-15 ohms on the engine harness side of X102 between the ignition circuit terminal A and the control circuit of the appropriate injector listed below: Injector 1 terminal C Injector 2 terminal D Injector 3 terminal E Injector 4 terminal F Injector 5 terminal G Injector 6 terminal H If the resistance is not within the specified range, test for a short to ground or an open/high resistance between X102 and the appropriate fuel injector harness connector. If the circuits test normal, test or replace the affected fuel injector.

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

  1. «Fuel Injector Replacement»(/chevrolet/impala/ix-2006-2016/remont/testing-diagnostics/#engine-controls-and-fuel-39l-repair-instructions)
  2. «Control Module References»(/chevrolet/impala/ix-2006-2016/remont/communication-devices/#programming-and-setup-all-systems__control-module-references) for ECM replacement, setup, and programming
  1. Perform the «Diagnostic System Check - Vehicle»(/chevrolet/impala/ix-2006-2016/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures) prior to using this diagnostic procedure.
  2. Review «Strategy Based Diagnosis»(/chevrolet/impala/ix-2006-2016/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»(/chevrolet/impala/ix-2006-2016/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures__diagnostic-procedure-instructions) provides an overview of each diagnostic category.

When an E85 compatible vehicle is built, an engine control module (ECM) or powertrain control module (PCM) replaced, or when the learned alcohol content has been reset with a scan tool, the fuel system will need to contain ASTM gasoline with 15 percent or less ethanol content. If the fuel in the fuel system needs to be drained and replaced with ASTM gasoline, the engine will need to run at operating temperature and consume at least 1 liter (0.3 gallon) of fuel before the system will recognize the correct alcohol content. Either ASTM gasoline or ASTM E85 fuel can then be used. In order that the ECM/PCM recognizes a proper next fuel fill, the amount must be 11 liters (3 gallons) or more, and the ethanol content must be between 0-85 percent.

Scan Tool Reference

Control Module References for scan tool information

Special Tools

  1. J 44175: Fuel Composition Tester
  2. J 44175-A: Fuel Composition Tester
  1. Observe the Fuel Composition Learn parameter using the scan tool. The Fuel Composition Learn parameter should display Inactive. IMPORTANT: The key needs to be turned OFF for at least 30 seconds after the parameter displays Inactive to properly store the ethanol learned value in the ECM/PCM memory. The vehicle may need to be driven more than 11 km (7 mi) with the engine at operating temperature. If the Fuel Composition Learn parameter displays Active, drive the vehicle until the Fuel Composition Learn parameter displays Inactive.
  2. Record the ECM/PCM estimated value of the ethanol content using a scan tool.
  3. Record the actual measured percentage of ethanol content using the J 44175: Tester or J 44175-A: Tester. The ECM/PCM estimated value should be within 15 percent of the ethanol content measured with the J 44175: Tester. If the ECM/PCM estimated value is not within 15 percent of the ethanol content measured with the J44175 Tester continue with Circuit/System Testing.

Circuit/System Testing - J44175 Ethanol Content Less Than 15 Percent

  1. Use the scan tool to reset the Fuel Alcohol Content parameter to 3 percent.
  2. Use the scan tool to reset the fuel trim values.

Circuit/System Testing - J44175 Ethanol Content More Than 15 Percent

  1. Perform a complete key cycle, key ON, engine OFF, in order to ensure that the ECM/PCM recognizes a refueling event.
  2. Key OFF, add at least 11 liters (3 gallons) of non-blended gasoline to the fuel tank.
  3. Use the scan tool to reset the Fuel Alcohol Content parameter to 3 percent.
  4. Drive the vehicle until the Fuel Composition Learn parameter displays Inactive.
  5. Use the scan tool to reset the fuel trim values.

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

  1. «Fuel System Cleaning»(/chevrolet/impala/ix-2006-2016/remont/testing-diagnostics/#engine-controls-and-fuel-39l-repair-instructions__fuel-system-cleaning)
  2. «Fuel Tank Draining (Non E-85)»(/chevrolet/impala/ix-2006-2016/remont/testing-diagnostics/#engine-controls-and-fuel-39l-repair-instructions)
  1. Perform the «Diagnostic System Check - Vehicle»(/chevrolet/impala/ix-2006-2016/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures) prior to using this diagnostic procedure.
  2. Review «Strategy Based Diagnosis»(/chevrolet/impala/ix-2006-2016/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»(/chevrolet/impala/ix-2006-2016/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures__diagnostic-procedure-instructions) provides an overview of each diagnostic category.

The control module enables the appropriate fuel injector pulse for each cylinder. The ignition voltage is supplied directly to the fuel injectors. The control module 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.

Schematic Reference

Connector End View Reference

  1. «Component Connector End Views -- Index»(/chevrolet/impala/ix-2006-2016/remont/body-electrical/#wiring-systems-and-power-management-component-connector-end-views-index)
  2. «Inline Harness Connector End Views»(/chevrolet/impala/ix-2006-2016/remont/body-electrical/#wiring-systems-and-power-management-inline-harness-connector-end-views)

Electrical Information Reference

  1. «Circuit Testing»(/chevrolet/impala/ix-2006-2016/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__circuit-testing)
  2. «Connector Repairs»(/chevrolet/impala/ix-2006-2016/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__connector-repairs)
  3. «Testing for Intermittent Conditions and Poor Connections»(/chevrolet/impala/ix-2006-2016/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures)
  4. «Wiring Repairs»(/chevrolet/impala/ix-2006-2016/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__wiring-repairs)

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. Refer to «Fuel Injector Balance Test»(/chevrolet/impala/ix-2006-2016/remont/testing-diagnostics/#engine-controls-and-fuel-39l-troubleshooting-diagnosis) . 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, perform the Fuel Injector Balance Test. Refer to «Fuel Injector Balance Test»(/chevrolet/impala/ix-2006-2016/remont/testing-diagnostics/#engine-controls-and-fuel-39l-troubleshooting-diagnosis) . 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.

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

  1. Perform the «Diagnostic System Check - Vehicle»(/chevrolet/impala/ix-2006-2016/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures) prior to using this diagnostic procedure.
  2. Review «Strategy Based Diagnosis»(/chevrolet/impala/ix-2006-2016/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»(/chevrolet/impala/ix-2006-2016/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures__diagnostic-procedure-instructions) provide an overview of each diagnostic category.

When performing the fuel injector balance test with the fuel injector tester or the scan tool, 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 fuel to be injected. This causes a drop in the system fuel pressure that can be recorded and used to compare each injector.

The CH 47976: Active Fuel Injector Tester (AFIT), is used to test the fuel pump, fuel system leak down, and the fuel injectors. 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.

  1. Monitoring the Current Misfire 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.

Schematic Reference

Connector End View Reference

  1. «Component Connector End Views -- Index»(/chevrolet/impala/ix-2006-2016/remont/body-electrical/#wiring-systems-and-power-management-component-connector-end-views-index)
  2. «Inline Harness Connector End Views»(/chevrolet/impala/ix-2006-2016/remont/body-electrical/#wiring-systems-and-power-management-inline-harness-connector-end-views)

Electrical Information Reference

  1. «Circuit Testing»(/chevrolet/impala/ix-2006-2016/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__circuit-testing)
  2. «Connector Repairs»(/chevrolet/impala/ix-2006-2016/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__connector-repairs)
  3. «Testing for Intermittent Conditions and Poor Connections»(/chevrolet/impala/ix-2006-2016/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures)
  4. «Wiring Repairs»(/chevrolet/impala/ix-2006-2016/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 47976: Active Fuel Injector Tester
  2. CH 48027: Digital Pressure Gauge
  3. J 39021: Fuel Injector Coil and Balance Tester
  4. J 39021-210: Injector Tester Adapter Box
  5. J 39021-450: Fuel Injector Harness Adapter

Note. DO NOT perform this test if the engine coolant temperature (ECT) is above 94°C (201°F). Irregular fuel pressure readings may result due to hot soak fuel boiling. Verify that adequate fuel is in the fuel tank before proceeding with this diagnostic. Before proceeding with this test review the User Manual CH 48027-5 for Safety Information and Instructions.

Fuel Injector Balance Test-Fuel Pressure Test

  1. Install a fuel pressure gauge. Refer to «Fuel Pressure Gauge Installation and Removal»(/chevrolet/impala/ix-2006-2016/remont/testing-diagnostics/#engine-controls-and-fuel-39l-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 386-427 kPa (56-62 psi). If the fuel pressure is not within the specified range, refer to «Fuel System Diagnosis»(/chevrolet/impala/ix-2006-2016/remont/testing-diagnostics/#engine-controls-and-fuel-39l-troubleshooting-diagnosis) .
  5. Monitor the fuel pressure gauge for one minute. 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»(/chevrolet/impala/ix-2006-2016/remont/testing-diagnostics/#engine-controls-and-fuel-39l-troubleshooting-diagnosis) .
  6. Perform the Fuel Injector Balance Test with Special Tool, the Fuel Injector Balance Test with Tech 2, or the Fuel Injector Balance Test with the Active Fuel Injector Tester.

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 A position.
  2. Disconnect the multi-way harness connector of the fuel injectors.
  3. Connect the J 39021: Fuel Injector Coil and Balance Tester, the J 39021-210: Injector Tester Adapter Box, and the J 39021-450: Fuel Injector Harness Adapter to the fuel injector multi-way harness connector.
  4. 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.
  5. 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: Fuel Injector Coil and Balance Tester at the previously selected pressure.
  6. After the injector stops pulsing, select Min from the Display Mode on the CH 48027: Gauge and record the Min pressure.
  7. Clear the Min/Max results on the CH 48027: Gauge.
  8. Select Normal from the Display Mode on the CH 48027: Gauge.
  9. Repeat steps 5 through 8 for each fuel injector.
  10. Subtract the minimum pressure from the starting pressure for one fuel injector. The result is the pressure drop value.
  11. Obtain a pressure drop value for each fuel injector.
  12. Add all of the individual pressure drop values except for the injector suspected of being faulty. This is the total pressure drop.
  13. 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.

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: Gauge and record the Min pressure.
  7. Clear the Min/Max results on the CH 48027: Gauge.
  8. Select Normal from the Display Mode on the CH 48027: Gauge.
  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. Subtract the minimum pressure from the starting pressure for one fuel injector. The result is the pressure drop value.
  12. Obtain a pressure drop value for each fuel injector.
  13. Add all of the individual pressure drop values except for the injector suspected of being faulty. This is the total pressure drop.
  14. 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.

Fuel Injector Balance Test with the Active Fuel Injector Tester

  1. Turn OFF all accessories.
  2. Turn OFF the ignition.
  3. Install the Active Fuel Injector Tester. Refer to the Active Fuel Injector Tester User Guide.
  4. Turn ON the Active Fuel Injector Tester and select the vehicle.
  5. Turn ON the ignition and perform the Injector Test. If the Active Fuel Injector Tester aborts testing due to fuel pressure or fuel leak down, refer to «Fuel System Diagnosis»(/chevrolet/impala/ix-2006-2016/remont/testing-diagnostics/#engine-controls-and-fuel-39l-troubleshooting-diagnosis) .
  6. View the test results. If any injector exceeds the recommended tolerance, replace the injector(s).

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

  1. Perform the «Diagnostic System Check - Vehicle»(/chevrolet/impala/ix-2006-2016/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures) prior to using this diagnostic procedure.
  2. Review «Strategy Based Diagnosis»(/chevrolet/impala/ix-2006-2016/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»(/chevrolet/impala/ix-2006-2016/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures__diagnostic-procedure-instructions) provides an overview of each diagnostic category.

Test 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.

Ethanol concentrations of greater than 10 percent in nonblended gasoline or greater than 85 percent with E85 blended gasoline for flexible fuel applications can cause 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.

Special Tools

J 44175 Fuel Composition Tester

System Verification

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.

  1. If the sample appears cloudy, or contaminated with water, as indicated by a water layer at the bottom of the sample, perform the Particulate Contaminants in Fuel Testing Procedure.
  2. If alcohol contamination is suspected, perform the Alcohol in Fuel Testing procedure.

Alcohol in Fuel Testing with Special Tool

  1. Test the fuel composition using J 44175 and Instruction Manual.
  2. If water appears in the fuel sample, clean the fuel system.
  3. Subtract 50 from the reading on the DMM in order to obtain the percentage of alcohol in the fuel sample.
  4. If the nonblended gasoline fuel sample measures more than 15 percent ethanol, or if the E85 blended gasoline fuel sample measures more than 91 percent ethanol, add fresh regular gasoline to the vehicle's fuel tank.
  5. Test the fuel composition.
  6. If additional testing indicates that the ethanol percentage is still above 15 percent for a nonblended gasoline sample, drain and replace the vehicle's fuel. Refer to «Fuel Tank Draining (E-85)»(/chevrolet/impala/ix-2006-2016/remont/testing-diagnostics/#engine-controls-and-fuel-35l-repair-instructions) . If additional testing indicates that the E85 blended gasoline sample still measures above 91 percent, continue adding fresh, regular gasoline until the ethanol content is 85 percent or less.

Alcohol in Fuel Testing without Special Tool

  1. Using a 100 ml (3.38 oz) specified cylinder with 1 ml (0.034 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 (3.38 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

  1. Using an approved fuel container, draw approximately 0.5 liter (0.53 qt) of fuel.
  2. Place the container 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.
  3. Observe the fuel sample. If any physical contaminants or water are present, clean the fuel system.

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

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»(/chevrolet/impala/ix-2006-2016/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures) prior to using this diagnostic procedure.
  2. Review «Strategy Based Diagnosis»(/chevrolet/impala/ix-2006-2016/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»(/chevrolet/impala/ix-2006-2016/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 (IC) module. The IC module contains coil driver circuits that command the coils to operate. The IC module 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 IC module for the proper coil to enable a spark event.

Inspect the spark plug wires for proper orientation.

Schematic Reference

Connector End View Reference

Description and Operation

Electrical Information Reference

  1. «Circuit Testing»(/chevrolet/impala/ix-2006-2016/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__circuit-testing)
  2. «Connector Repairs»(/chevrolet/impala/ix-2006-2016/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__connector-repairs)
  3. «Wiring Repairs»(/chevrolet/impala/ix-2006-2016/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 26792 Spark Tester

  1. With the ignition OFF, remove the fuel pump relay.
  2. Crank the engine and test for a strong spark on each cylinder spark plug wire using the J 26792 . Ground the companion cylinder spark plug wire of each cylinder when it is tested. If a strong 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 Inspection»(/chevrolet/impala/ix-2006-2016/remont/testing-diagnostics/#engine-controls-and-fuel-39l-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 IC module for an open/high resistance or short to ground, or test the ground circuit of the IC module for an open/high resistance, or a faulty IC module. The wire circuit resistance should measure less than 3 ohms. If spark is present on one or more of the cylinders, inspect the spark plug wires for arching, cuts, rubbing on other components, and proper resistance, refer to «Spark Plug Wire Inspection»(/chevrolet/impala/ix-2006-2016/remont/testing-diagnostics/#engine-controls-and-fuel-39l-repair-instructions__spark-plug-wire-inspection) . If all tests are normal, then the system is operating correctly.
  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 IC module. If the resistance is not within the specified range, replace the IC module.
  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 IC module. If the resistance is not within the specified range, replace the IC module.

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

  1. «Spark Plug Wire Replacement»(/chevrolet/impala/ix-2006-2016/remont/testing-diagnostics/#engine-controls-and-fuel-39l-repair-instructions)
  2. «Spark Plug Replacement»(/chevrolet/impala/ix-2006-2016/remont/testing-diagnostics/#engine-controls-and-fuel-39l-repair-instructions)
  3. «Ignition Coil Replacement»(/chevrolet/impala/ix-2006-2016/remont/testing-diagnostics/#engine-controls-and-fuel-39l-repair-instructions)
  1. Perform the «Diagnostic System Check - Vehicle»(/chevrolet/impala/ix-2006-2016/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures) prior to using this diagnostic procedure.
  2. Review «Strategy Based Diagnosis»(/chevrolet/impala/ix-2006-2016/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»(/chevrolet/impala/ix-2006-2016/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures__diagnostic-procedure-instructions) provides an overview of each diagnostic category.

Description

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 complies with the local area requirements. While testing in the I/M System Status mode, some DTCs may occur that are called I/M Test DTCs. An I/M Test DTC is defined as a fault code that is currently commanding the MIL ON, and is stored in non-volatile memory. The intended use of this data is to prevent vehicles from passing I/M inspection without proper repair to the vehicle. These fault codes are not erasable from any scan tool command or erasable by disconnecting power to the controller. The I/M Test DTCs will be supported by all emissions related ECUs such as ECMs, TCMs, FPCMs, etc. An I/M Test DTC will not be stored or erased from the ECU except at the end of trip processing which occurs 5 s after ignition OFF.

Conditions for Updating the I/M System Status

Each system requires at least one, and sometimes several, diagnostic tests. The results of these tests are reported by a diagnostic trouble code (DTC). A system monitor is complete when either all of the DTCs comprising the monitor have Run and Passed, or any one of the DTCs comprising the monitor have illuminated the malfunction indicator lamp (MIL). Once all of the tests are completed, 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 four heated oxygen sensors, either all four 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 as part of a service procedure.

Conditions for Clearing I/M Test DTCs

  1. Only the OBD II System can erase the I/M Test DTC. The OBD II system must determine that the malfunction that caused the I/M Test DTC to be stored is no longer present and is not commanding the MIL. Each of the following represents ways to clear an I/M Test DTC: If the MIL goes out due to 3 passing drive cycles, scan tool code clear is not used, the I/M Test DTC is erased at power down of the last drive cycle. If a scan tool code clear is used to turn OFF the MIL, the I/M Test DTC is not erased, the DTC must PASS and not FAIL. The I/M Test DTC is erased at power down of the drive cycle. If the controller is reflashed/reprogrammed, all I/M Test DTCs are erased.
  2. For the OBD II System to run a single drive cycle for clearing an I/M Test DTC, all of the following conditions must occur: Cumulative time of engine run time is greater than 600 s. Cumulative vehicle operation above 41 kPa (25 mph) for over 300 s. Continuous vehicle idle for greater than 30 s. Turn ignition OFF for 5 s and allow the code to clear.

Monitored Emission Control Systems

The OBD II system monitors all emission control systems that are on-board. Not all vehicles need every possible emission control system. For example, a vehicle may not be equipped with secondary air injection (AIR) or exhaust gas recirculation (EGR). The OBD II regulations require monitoring of the following, if equipped

  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 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.

The I/M System Status display provides an indication of when the control module has completed the required tests. This does not necessarily mean that the test has passed, only that a decision was made. If the diagnostic fails, a DTC will indicate the failure. If a failure indication is present for a DTC associated with one of the I/M regulated systems, it may prevent other required tests from running. For example, a DTC for the control circuit of the EVAP purge solenoid may not be listed in the Inspection/Maintenance System DTC Table because it is a continuous test. If this DTC is set, the Active Tests for the EVAP system may not run.

The I/M System Status information may be useful for a technician to determine if diagnostics have run when verifying repairs.

Review the I/M System Status indicators. All I/M System Status indicators should report YES, and no I/M Test DTCs should be present.

  1. Observe the Engine DTC information with a scan tool. Verify no DTCs are present. If a DTC is set that would prevent the I/M System Status tests from completing, diagnose that DTC before continuing. Refer to «Diagnostic Trouble Code (DTC) List - Vehicle»(/chevrolet/impala/ix-2006-2016/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures__diagnostic-trouble-code-dtc-list) .
  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»(/chevrolet/impala/ix-2006-2016/remont/testing-diagnostics/#engine-controls-and-fuel-39l-troubleshooting-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»(/chevrolet/impala/ix-2006-2016/remont/testing-diagnostics/#engine-controls-and-fuel-39l-troubleshooting-diagnosis) .
  4. Observe the I/M Test DTC information with a scan tool. Verify there are no I/M Test DTCs present. If an I/M Test DTC is set and all of the I/M System Status indicators are Yes, there is no need to perform the Complete System Set Procedure. Diagnose the DTC using the «Diagnostic Trouble Code (DTC) List - Vehicle»(/chevrolet/impala/ix-2006-2016/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures__diagnostic-trouble-code-dtc-list) and refer to Conditions for Clearing the I/M Test DTCs. If an I/M Test DTC is set and the I/M System Status indicators are NO, diagnosis the DTC and perform the «Inspection/Maintenance Complete System Set Procedure»(/chevrolet/impala/ix-2006-2016/remont/testing-diagnostics/#engine-controls-and-fuel-39l-troubleshooting-diagnosis) .
  1. Perform the «Diagnostic System Check - Vehicle»(/chevrolet/impala/ix-2006-2016/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures) prior to using this diagnostic procedure.
  2. Review «Strategy Based Diagnosis»(/chevrolet/impala/ix-2006-2016/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»(/chevrolet/impala/ix-2006-2016/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 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 trips 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 Inspection/Maintenance (I/M) Complete System Set Procedure if any I/M System Status indicators are set to NO.

Conditions for Meeting a Cold Start

  1. The ignition voltage between 10-15 V.
  2. The barometric pressure (BARO) is more than 75 kPa.
  3. The engine coolant temperature (ECT) at start-up is less than 42°C (108°F).
  4. The intake air temperature (IAT) is between 2-32°C (36-90°F).
  5. The engine is OFF for greater than 6 h or the following conditions must be met: The start-up IAT minus start-up ECT are within 12°C (22°F). The start-up ECT minus start-up IAT are within 50°C (90°F).
  6. Fuel level is between 25 and 75 %.

Review the Inspection/Maintenance (I/M) System Status indicators. All I/M System Status indicators should report YES, and no I/M Test DTCs should be present.

Inspection/Maintenance (I/M) System Set Procedure

  1. Ensure that the vehicle meets the conditions for a cold start listed above. If the EVAP I/M System Status indicator displays NO, perform the EVAP Service bay test if applicable.
  2. Turn OFF all accessories; HVAC system, other electrical loads, including aftermarket/add-on equipment, etc., and open the hood.
  3. Set the vehicle parking brake and ensure the vehicle is in park for automatic transmission or neutral for manual transmission.
  4. Start and idle the engine for 2 min.
  5. Close the hood, release the parking brake and Accelerate at part throttle to 72-80 km/h (45-50 mph) with this speed maintained until the engine reaches operating temperature, 8-10 min.
  6. Continue operation under these conditions for an additional 6 min.
  7. Accelerate at part throttle to 90 km/h (55 mph) with this speed maintained for 2 min.
  8. Release the accelerator pedal for at least 10 s. This will allow the vehicle to enter the decel fuel cut off.
  9. Safely stop the vehicle, with the engine in drive for automatic or neutral with the clutch pedal depressed and parking brake applied for manual. Allow the vehicle to idle for 2 min.
  10. Shift the vehicle to park for automatic and neutral for manual. Turn OFF the ignition and exit the vehicle. Do NOT disturb the vehicle for 45 min.
  11. 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, ensure that the vehicle meets the conditions for a cold start, and repeat steps 6-11 three 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»(/chevrolet/impala/ix-2006-2016/remont/testing-diagnostics/#engine-controls-and-fuel-39l-troubleshooting-diagnosis__inspectionmaintenance-im-test-dtc-table) to identify the DTCs that did not run. If any of the I/M System Status indicators display NO, refer to the «Inspection/Maintenance (I/M) Test DTC Table»(/chevrolet/impala/ix-2006-2016/remont/testing-diagnostics/#engine-controls-and-fuel-39l-troubleshooting-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.
  12. Observe the I/M Test DTC information with a scan tool. Verify there are no I/M Test DTCs present. If an I/M Test DTC is set, diagnose the DTC using the «Diagnostic Trouble Code (DTC) List - Vehicle»(/chevrolet/impala/ix-2006-2016/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures__diagnostic-trouble-code-dtc-list) and refer to «Inspection/Maintenance System Check»(/chevrolet/impala/ix-2006-2016/remont/testing-diagnostics/#engine-controls-and-fuel-39l-troubleshooting-diagnosis) .
  13. 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»(/chevrolet/impala/ix-2006-2016/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»(/chevrolet/impala/ix-2006-2016/remont/testing-diagnostics/#engine-controls-and-fuel-39l-troubleshooting-diagnosis) to verify no further DTCs are set.

Inspection/Maintenance (I/M) Test DTC Table

SystemDTCs Required to Set System Status to YES
If an inspection/maintenance system status indicator did NOT update to YES during the Inspection/Maintenance Complete System Set Procedure , review each indicator and reference this table to determine each DTC associated with the inspection/maintenance system status indicator. Each DTC listed below has specific conditions that must be met for the diagnostic to run. Included within the conditions are additional DTCs which, if set, may inhibit the DTCs listed below from running. Reviewing and operating the vehicle within the Conditions for Running for each DTC listed below will allow the inspection/maintenance system status indicators to transition to YES.
CatalystDTC P0420
Evaporative EmissionDTC P0442 DTC P0446 DTC P0451-P0454 DTC P0455 DTC P0496
Oxygen SensorDTC P0133, P0134, P013A, P013B, P013E, P013F, P0140, P1133, P2270, P2271, or P2A00
Oxygen Sensor HeaterDTC P0030, P0036, P0053, P0054, P0135, or P0141
Camshaft SystemDTC P0011
  1. Perform the «Diagnostic System Check - Vehicle»(/chevrolet/impala/ix-2006-2016/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures) prior to using this diagnostic procedure.
  2. Review «Strategy Based Diagnosis»(/chevrolet/impala/ix-2006-2016/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»(/chevrolet/impala/ix-2006-2016/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.

Test Procedure

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
• Control Module References
• Testing for Intermittent Conditions and Poor Connections
• Spark Plug Inspection
• Ignition System Specifications
• Torque Converter Diagnosis
• DTC P0171 or P0172
• Symptoms - Engine Exhaust
• Symptoms - Engine Cooling
• Symptoms - Engine Mechanical
• Temperature Versus Resistance
• Symptoms - Engine Electrical
• Crankshaft and Bearing Cleaning and Inspection
• Camshaft Position Actuator Cleaning and Inspection
• Camshaft Position Actuator Magnet Cleaning and Inspection
• Mass Airflow Sensor with Intake Air Temperature Sensor Replacement
• Engine Mount Inspection
• Instrument Cluster Schematics
• Engine Controls Schematics
• Component Connector End Views -- Index
• Circuit Testing
• Connector Repairs
• Wiring Repairs
• Diagnostic Repair Verification
• Battery Inspection/Test
• Engine Cranks Slowly
• Starting System Description and Operation
• Diagnostic Trouble Code (DTC) List - Vehicle
• Altitude Versus Barometric Pressure
• DTC P0685, P0689, P0690, or P1682
• Spark Plug Wire Inspection
• Restricted Exhaust
• Spark Plug Replacement
• Electrical Center Identification Views
• Relay Replacement (Attached to Wire Harness)
• Fuel System Description
• Fuel Pressure Relief (Without CH 48027)
• Inline Harness Connector End Views
• Fuel System Cleaning
• Road Test Warning
• Fuel System Diagnosis
• Inspection/Maintenance (I/M) Test DTC Table

More articles — Engine Performance