Engine Controls - 5.3l - Troubleshooting Pontiac Grand Prix VII

Important Preliminary Inspections Before Starting

Perform Diagnostic System Check - Vehicle in Vehicle DTC Information before using the symptom tables, and verify that all of the following are true

1. The engine control module (ECM) and malfunction indicator lamp (MIL) are operating correctly.
2. There are no DTCs stored.
3. The scan tool data is within the normal operating range, refer to «Scan Tool Data List»(/pontiac/grand-prix/vii-2004-2008/remont/testing-diagnostics/#engine-controls-53l-introduction-1-of-2__scan-tool-data-list) .
4. Verify the customer concern and locate the correct symptom in the table of contents. Inspect the items indicated under that symptom.

Visual/Physical Inspection

Several of the symptom procedures ask for a careful visual and physical inspection. This step is extremely important. The visual and physical inspection can lead to correcting a problem without further inspections, and can save valuable time. Ensure that

1. The ECM grounds are clean, tight, and in the proper location.
2. The vacuum hoses are not split or kinked, and properly connected, as shown on the Vehicle Emission Control Information label. Inspect thoroughly for any type of leak or restriction.
3. The mass air flow (MAF) sensor is properly installed. The arrows on the plastic portion of the sensor must point toward the engine.
4. The air intake ducts are not collapsed or damaged.
5. There are no leaks at the throttle body mounting area, the MAF sensor, or the intake manifold sealing surfaces.
6. The ignition wires are not cracked, brittle, or carbon tracked.
7. The engine harness wiring and terminals are properly connected and are not pinched or cut.

Intermittent

Faulty electrical connections or wiring cause most intermittent problems. Perform a careful visual and physical inspection of the suspect connectors for the following conditions

1. Improperly mated connector halves
2. Terminals that are not seated
3. Terminals that are damaged or improperly formed

Reform or replace connector terminals in the problem circuit in order to ensure proper contact tension. Refer to Connector Repairs in Wiring Systems. Remove the terminal from the connector body in order to inspect for poor terminal wire connection. Refer to Testing for Intermittent Conditions and Poor Connections in Wiring Systems.

Road test the vehicle with the DMM connected to the suspected circuit. An abnormal reading that occurs when the malfunction occurs is a good indication that there is a malfunction in the circuit being monitored.

Use a scan tool in order to help detect intermittent conditions. Useful features of the GM Techline scan tool include the following

1. Trigger the Snapshot feature in order to capture and store engine parameters when the malfunction occurs. Review this stored information in order to see the specific running conditions that caused the malfunction.
2. Freeze Frame/Failure Records can also aid in locating an intermittent condition. Review and capture the information in the Freeze Frame/Failure Record associated with the intermittent DTC being diagnosed. Drive the vehicle within the conditions that were present when the DTC originally set.
3. Use the Plot Function on the scan tool in order to plot selected data parameters. Review this stored information to aid in locating an intermittent problem. Refer to the scan tool Users Guide for more information.

Any of the following may cause an intermittent MIL with no stored DTC

1. The ignition coils are shorted to a ground or arcing at the ignition wires or the spark plugs.
2. The ECM grounds are loose or dirty. Refer to «Engine Controls Schematics»(/pontiac/grand-prix/vii-2004-2008/remont/testing-diagnostics/#engine-controls-53l-introduction-2-of-2) .
3. The ignition control (IC) wires are routed too close to the secondary ignition wires, coils, or the generator. Ensure that all of the circuits from the ECM to the ignition coils have good connections.
4. There is an open diode across the A/C compressor clutch or any other open diodes.

Use the following tables when diagnosing a symptom complaint

1. «Testing for Intermittent Conditions and Poor Connections»(/pontiac/grand-prix/vii-2004-2008/remont/body-electrical/#how-to-diagnosis-repair-the-wiring-systems-testing__testing-for-intermittent-conditions-and-poor)
2. «Hard Start»(/pontiac/grand-prix/vii-2004-2008/remont/testing-diagnostics/#engine-controls-53l-troubleshooting__hard-start)
3. «Surges/Chuggles»(/pontiac/grand-prix/vii-2004-2008/remont/testing-diagnostics/#engine-controls-53l-troubleshooting__surgeschuggles)
4. «Lack of Power, Sluggishness, or Sponginess»(/pontiac/grand-prix/vii-2004-2008/remont/testing-diagnostics/#engine-controls-53l-troubleshooting__lack-of-power-sluggishness-or-sponginess)
5. «Detonation/Spark Knock»(/pontiac/grand-prix/vii-2004-2008/remont/testing-diagnostics/#engine-controls-53l-troubleshooting__detonationspark-knock)
6. «Hesitation, Sag, Stumble»(/pontiac/grand-prix/vii-2004-2008/remont/testing-diagnostics/#engine-controls-53l-troubleshooting__hesitation-sag-stumble)
7. «Cuts Out, Misses»(/pontiac/grand-prix/vii-2004-2008/remont/testing-diagnostics/#engine-controls-53l-troubleshooting__cuts-out-misses)
8. «Poor Fuel Economy»(/pontiac/grand-prix/vii-2004-2008/remont/testing-diagnostics/#engine-controls-53l-troubleshooting__poor-fuel-economy)
9. «Poor Fuel Fill Quality»(/pontiac/grand-prix/vii-2004-2008/remont/testing-diagnostics/#engine-controls-53l-troubleshooting__poor-fuel-fill-quality)
10. «Rough, Unstable, or Incorrect Idle and Stalling»(/pontiac/grand-prix/vii-2004-2008/remont/testing-diagnostics/#engine-controls-53l-troubleshooting__rough-unstable-or-incorrect-idle-and)
11. «Dieseling, Run-On»(/pontiac/grand-prix/vii-2004-2008/remont/testing-diagnostics/#engine-controls-53l-troubleshooting__dieseling-run-on)
12. «Backfire»(/pontiac/grand-prix/vii-2004-2008/remont/testing-diagnostics/#engine-controls-53l-troubleshooting__backfire)

Hard Start

Hard Start

Surges/Chuggles

Surges/Chuggles

Lack of Power, Sluggishness or Sponginess

Lack of Power, Sluggishness, or Sponginess

Detonation/Spark Knock

Detonation/Spark Knock

Hesitation, Sag, Stumble

Hesitation, Sag, Stumble

Cuts Out, Misses

Cuts Out, Misses

Poor Fuel Economy

Poor Fuel Economy

Poor Fuel Fill Quality

Poor Fuel Fill Quality

Rough, Unstable, or Incorrect Idle and Stalling

Rough, Unstable, or Incorrect Idle and Stalling

Dieseling, Run-On

Dieseling, Run-On

Backfire

Backfire

Circuit Description

Ignition voltage is supplied to the malfunction indicator lamp (MIL). The engine control module (ECM) turns the MIL ON by grounding the MIL control circuit. There should be a steady MIL with the ignition ON and the engine OFF.

MIL Operation

The MIL is located on the instrument panel cluster (IPC).

MIL Function

1. The MIL informs the driver that a malfunction has occurred and the vehicle should be taken in for service as soon as possible.
2. The MIL illuminates during a bulb test and a system test.
3. A DTC will be stored if a MIL is requested by the ECM.

MIL Illumination

1. The MIL will illuminate with ignition switch ON and the engine not running.
2. The MIL will turn OFF when the engine is started.
3. The MIL will remain ON if the self-diagnostic system has detected a malfunction.
4. The MIL may turn OFF if the malfunction is not present.
5. If the MIL is illuminated and then the engine stalls, the MIL will remain illuminated so long as the ignition switch is ON.
6. If the MIL is not illuminated and the engine stalls, the MIL will not illuminate until the ignition switch is cycled OFF, then ON.

Malfunction Indicator Lamp (MIL) Inoperative

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

The MIL is located on the instrument panel (IPC).

MIL Function

1. The MIL informs the driver that a malfunction has occurred and the vehicle should be taken in for service as soon as possible.
2. The MIL illuminates during a bulb test and a system test.
3. A DTC will be stored if a MIL is requested by the diagnostic.

MIL Illumination

1. The MIL will illuminate with ignition switch ON and the engine not running.
2. The MIL will turn OFF when the engine is started.
3. The MIL will remain ON if the self-diagnostic system has detected a malfunction.
4. The MIL may turn OFF if the malfunction is not present.
5. If the MIL is illuminated and then the engine stalls, the MIL will remain illuminated so long as the ignition switch is ON.
6. If the MIL is not illuminated and the engine stalls, the MIL will not illuminate until the ignition switch is cycled OFF, then ON.

Diagnostic Aids

If the problem is intermittent, refer to Testing for Intermittent Conditions and Poor Connections .

Test Description

The number below refers to the step number on the diagnostic table.

1. 2: This step determines if the condition is with the MIL control circuit or the ECM.

Malfunction Indicator Lamp (MIL) Always On

Description

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

1. The battery is completely charged. Refer to «Battery Inspection/Test»(/pontiac/grand-prix/vii-2004-2008/remont/charging-system/#battery-charging-system-and-starting-system) .
2. The engine cranking speed is acceptable. Refer to «Engine Cranks Slowly»(/pontiac/grand-prix/vii-2004-2008/remont/charging-system/#battery-charging-system-and-starting-system__engine-cranks-slowly) .
3. There is adequate fuel in the fuel tank.

Engine Cranks but Does Not Run

Diagnostic Fault Information

Always perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure.

Typical Scan Tool Data

EC Ignition Relay Feedback Signal

Circuit/System Description

The powertrain relay is a normally open relay. The relay armature is held in the open position by spring tension. Battery positive voltage is supplied directly to the relay coil and the armature contact at all times. The engine control module (ECM) supplies the ground path to the relay coil control circuit via an internal integrated circuit called an output driver module (ODM). The ODM output control is configured to operate as a low side driver for the powertrain relay. The ODM for the powertrain relay also incorporates a fault detection circuit, which is continuously monitored by the ECM. When the ECM commands the powertrain relay ON, ignition 1 voltage is supplied to the following fuses and relay in the underhood fuse block

1. The ETC/ECM Fuse
2. INJ 1 Fuse
3. INJ 2 Fuse
4. Emission 1 Fuse
5. Emission 2 Fuse

The ignition 1 voltage that is supplied to the ECM through the ETC/ECM fuse, provides power to the internal ECM circuits associated with the throttle actuator control (TAC) operation. The ECM also monitors the voltage level on the ignition 1 voltage circuit to confirm that the powertrain relay contacts have closed.

1. This test procedure requires that the vehicle battery has passed a load test and is completely charged. Refer to «Battery Inspection/Test»(/pontiac/grand-prix/vii-2004-2008/remont/charging-system/#battery-charging-system-and-starting-system) .
2. When disconnecting electrical connectors or removing fuses and relays from a fuse block, always inspect the component electrical terminals for corrosion and the mating electrical terminals for tightness.
3. Use the J 35616 Connector Test Adapter Kit for any test that requires probing the underhood fuse block terminals, component wire harness terminals, or the ECM wire harness connector terminals.

Schematic Reference

Engine Controls Schematics

Connector End View Reference

1. «Engine Controls Connector End Views»(/pontiac/grand-prix/vii-2004-2008/remont/testing-diagnostics/#engine-controls-53l-introduction-2-of-2__engine-controls-connector-end-views)
2. «Electrical Center Identification Views»(/pontiac/grand-prix/vii-2004-2008/remont/electrical-component-locations/#wiring-systems-component-views)
3. «Engine Control Module (ECM) Connector End Views»(/pontiac/grand-prix/vii-2004-2008/remont/testing-diagnostics/#engine-controls-53l-introduction-2-of-2__engine-control-module-ecm-connector-end)

Electrical Information Reference

1. «Circuit Testing»(/pontiac/grand-prix/vii-2004-2008/remont/body-electrical/#how-to-diagnosis-repair-the-wiring-systems-testing__circuit-testing)
2. «Connector Repairs»(/pontiac/grand-prix/vii-2004-2008/remont/body-electrical/#how-to-diagnosis-repair-the-wiring-systems-testing__connector-repairs)
3. «Testing for Intermittent Conditions and Poor Connections»(/pontiac/grand-prix/vii-2004-2008/remont/body-electrical/#how-to-diagnosis-repair-the-wiring-systems-testing__testing-for-intermittent-conditions-and-poor)
4. «Wiring Repairs»(/pontiac/grand-prix/vii-2004-2008/remont/body-electrical/#how-to-diagnosis-repair-the-wiring-systems-testing__wiring-repairs)

Scan Tool Reference

1. «Scan Tool Data List»(/pontiac/grand-prix/vii-2004-2008/remont/testing-diagnostics/#engine-controls-53l-introduction-1-of-2__scan-tool-data-list)
2. «Scan Tool Data Definitions»(/pontiac/grand-prix/vii-2004-2008/remont/testing-diagnostics/#engine-controls-53l-introduction-1-of-2__scan-tool-data-definitions)
3. «Scan Tool Output Controls»(/pontiac/grand-prix/vii-2004-2008/remont/testing-diagnostics/#engine-controls-53l-introduction-1-of-2__scan-tool-output-controls)

Special Tools Required

J 43244 Relay Puller Pliers

Circuit/System Verification

1. With the ignition ON, engine OFF, command the powertrain relay ON and OFF several times using the scan tool output control function. You should either hear or feel the relay click with each command.
2. With the ignition ON, engine OFF, probe both test points of each of the following fuses: ETC/ECM Fuse INJ 1 Fuse INJ 2 Fuse Emission 1 Fuse Emission 2 Fuse The test lamp should illuminate on at least one test point of each fuse. If the test lamp does not illuminate continue with Circuit/System Testing.

Circuit/System Testing

1. With the ignition OFF, remove the powertrain relay from the underhood fuse block.
2. With the ignition ON, measure for battery positive voltage (B+) between the relay coil voltage supply circuit and ground. If the voltage measures less than B+, repair the open or high resistance in the circuit to the relay coil. All wire circuit resistance should measure less than 2 ohms.
3. Measure for voltage between the relay coil control circuit and ground. If voltage is measured on the control circuit of the relay, test for a short to voltage or a faulty ECM.
4. Connect a test lamp between the battery positive voltage supply circuit of the relay coil and the relay coil control circuit at the underhood fuse block. Use a scan tool to command the powertrain relay ON and OFF. The test lamp should turn ON and OFF when toggling between the commanded states. If the test lamp stays ON all the time, test for a short to ground on the relay coil control circuit or a faulty ECM. If the test lamp stays OFF all the time, test for an open or high resistance on the relay coil control circuit or a faulty ECM. All wire circuit resistance should measure less than 2 ohms.
5. Measure for B+ between the relay armature supply circuit, and ground. If the voltage measures less than B+, repair the open or high resistance in the circuit to the relay armature. All wire circuit resistance should measure less than 2 ohms.
6. With the ignition ON, test for voltage on each test point of the ETC/ECM fuse in the underhood fuse block. If voltage is present, test the ignition 1 voltage circuit between the ECM, the powertrain relay, and the ETC/ECM fuse for a short to voltage. If both circuits test normal, replace the ECM.
7. Connect a 20-amp fused jumper wire between the B+ terminal and the ignition 1 voltage terminal of the powertrain relay at the underhood fuse block. With a test lamp, probe both test points of the ETC/ECM fuse. If the test lamp illuminates at both test points of the ETC/ECM fuse, repair the ignition 1 voltage circuit between the powertrain relay and the ECM for an open, high resistance, or a faulty ECM. All wire circuit resistance should measure less than 2 ohms. If the test lamp only illuminates at one test point of the ETC/ECM fuse, repair the short to ground in the ignition 1 voltage circuit between the fuse and the applicable component. Replace the fuse as necessary. If the test lamp does not illuminate on either test point of the ETC/ECM fuse, repair the open or high resistance between the powertrain relay and the ETC/ECM fuse. All wire circuit resistance should measure 2 ohms or less.
8. With a test lamp, test for voltage on both test points of the following fuses: ETC/ECM Fuse INJ 1 Fuse INJ 2 Fuse Emission 1 Fuse Emission 2 Fuse If the test lamp fails to illuminate on one test point of each fuse, repair the open or high resistance between the fuse and the powertrain relay. All wire circuit resistance should measure 2 ohms or less.

Component Testing

1. Measure for 70-110 ohms between terminals 85 and 86 of the relay. If the resistance is not within the specified range, replace the relay.
2. Measure for infinite resistance between terminals 30 and 86 of the relay. If continuity is detected, replace the relay.
3. Measure for infinite resistance between terminals 30 and 87 of the relay. If continuity is detected, replace the relay.
4. Measure for infinite resistance between terminals 30 and 85 of the relay. If continuity is detected, replace the relay.
5. Measure for infinite resistance between terminals 85 and 87 of the relay. If continuity is detected, replace the relay.
6. Connect a 20-amp fused jumper wire from the battery positive cable at the battery, to relay terminal 85. Connect a jumper wire from the negative battery cable at the battery, to relay terminal 86. Measure for less than 2 ohms between terminals 30 and 87 of the relay, with a DMM. If the resistance measures more than 2 ohms, replace the relay.

Repair Procedures

1. «Relay Replacement (Within an Electrical Center)»(/pontiac/grand-prix/vii-2004-2008/remont/body-electrical/#how-to-diagnosis-repair-the-wiring-systems-testing) or «Relay Replacement (Attached to Wire Harness)»(/pontiac/grand-prix/vii-2004-2008/remont/body-electrical/#how-to-diagnosis-repair-the-wiring-systems-testing)
2. «Underhood Electrical Center or Junction Block Replacement»(/pontiac/grand-prix/vii-2004-2008/remont/body-electrical/#how-to-diagnosis-repair-the-wiring-systems-testing)
3. «Engine Control Module Programming and Setup»(/pontiac/grand-prix/vii-2004-2008/remont/communication-devices/#programming-and-setup-all-systems__engine-control-module-programming-and-setup)

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 two 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 two seconds if ignition reference pulses cease to be detected and the ignition remains ON.

The numbers below refer to the step numbers on the diagnostic table.

1. 2: This step determines if the condition is located on the coil side or on the switch side of the fuel pump relay.
2. 3: This step verifies that the engine control module (ECM) is providing voltage to the fuel pump relay.
3. 4: This step tests for an open in the ground circuit to the fuel pump relay.
4. 5: This step determines if a voltage is constantly being applied to the fuel pump relay.
5. 12: This step determines if the condition with the circuit is intermittent.

Fuel Pump Electrical Circuit Diagnosis

System Description

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 sender assembly, 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 sender assembly inside the fuel tank. The fuel pump supplies high pressure fuel through the fuel filter and the fuel feed pipe to the fuel injection system. The fuel pump provides fuel at a higher rate of flow than is needed by the fuel injection system. The fuel pump also supplies fuel to a venturi pump located on the bottom of the fuel sender assembly. The function of the venturi pump is to fill the fuel sender assembly reservoir. The fuel pressure regulator, a part of the fuel sender assembly, maintains the correct fuel pressure to the fuel injection system. The fuel pump and sender assembly 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.

Fuel System Diagnosis

The control module enables the appropriate fuel injector on the intake stroke for each cylinder. 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 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.

1. Monitoring the misfire current counters, or misfire graph, may help 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 customers concern. A fuel injector condition may only be apparent at a certain temperature, or under certain conditions.

Fuel Injector Coil Test

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

Fuel Injector Balance Test Example (Typical)

Fuel Injector Balance Test with Special Tool

The scan tool is first used to energize the fuel pump. The scan tool is then used to pulse each injector for a precise amount of time, allowing a measured amount of fuel into the manifold. This causes a drop in system fuel pressure that can be recorded and used to compare the flow through each injector.

Fuel Injector Balance Test Example (Typical)

Fuel Injector Balance Test with Tech 2

The fuel tank leak test is used to locate any fuel or fuel vapor escaping the fuel tank area. Fuel vapors escaping above the fuel level will be detected when the evaporative emission (EVAP) diagnostics complete one test cycle. The malfunction indicator lamp (MIL) will illuminate after the EVAP diagnostics have failed two test cycles.

1. Operate the vehicle under the condition of the customers concern. Under high temperature conditions fuel vapors may increase to the point of EVAP canister vapor saturation. Fuel vapors would then be released into the atmosphere. Once the engine is running and EVAP purge is enabled, all fuel vapor release would be eliminated.
2. Movement of the EVAP pipes or fuel pipes may help find an intermittent condition.
3. If the fuel level is low, a leak may not be evident.

The numbers below refer to the step numbers on the diagnostic table.

1. 4: This step tests for fuel leaks below the fuel tank fuel level.
2. 5: This step tests for fuel vapors escaping above the fuel level in the fuel tank.

Fuel Tank Leak Test

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

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

Test Procedure

1. Test the fuel composition using J 44175 Fuel Composition Tester and J 44175-3 Instruction Manual.
2. If water appears in the fuel sample, perform the following steps: Clean the fuel system. Refer to «Fuel System Cleaning»(/pontiac/grand-prix/vii-2004-2008/remont/testing-diagnostics/#engine-controls-53l-introduction-2-of-2__fuel-system-cleaning) . Replace the fuel filter if the vehicle is equipped with a serviceable fuel filter.
3. Subtract 50 from the reading on the DMM in order to obtain the percentage of alcohol in the fuel sample. Refer to the examples in the Fuel Composition Test Examples table.
4. If the fuel sample contains more than 15 percent ethanol, add fresh, regular gasoline to the vehicle's fuel tank.
5. Test the fuel composition.
6. If testing shows the ethanol percentage is still more than 15 percent, replace the fuel in the vehicle. Refer to «Fuel System Cleaning»(/pontiac/grand-prix/vii-2004-2008/remont/testing-diagnostics/#engine-controls-53l-introduction-2-of-2__fuel-system-cleaning) .

Fuel Composition Test Examples

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

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

Alcohol in Fuel Testing Procedure

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

1. Using a 100 ml specified cylinder with 1 ml graduation marks, fill the cylinder with fuel to the 90 ml mark.
2. Add 10 ml of water in order to bring the total fluid volume to 100 ml 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. For example, if the volume of the lower layer is increased to 15 ml, this indicates at least 5 percent alcohol in the fuel. The actual amount of alcohol may be somewhat more because this procedure does not extract all of the alcohol from the fuel.

Particulate Contaminants in Fuel Testing Procedure

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

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

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

The electronic ignition system uses an individual ignition coil for each cylinder. The engine control module (ECM) controls the ignition operation through eight individual ignition control (IC) circuits. Each bank of four ignition coils is connected to the ECM, power, or ground by the following circuits

1. A low reference circuit
2. A chassis ground circuit
3. An ignition 1 voltage circuit
4. The appropriate IC circuit

The ECM triggers an ignition coil by grounding the appropriate IC circuit using information from the crankshaft position (CKP) and camshaft position (CMP) sensors.

For an intermittent condition, refer to Testing for Intermittent Conditions and Poor Connections .

The numbers below refer to the step numbers on the diagnostic table.

1. 5: Monitoring the misfire current counters determines if a fault is present.
2. 12: A good indication that the fuse is open is all off the misfire current counters are incrementing on one side of the engine. Inspect the ignition positive voltage circuit for a grounded circuit. If the fuse is open and the ignition coil circuits are OK, inspect the injector circuits for being grounded.

Electronic Ignition (EI) System Diagnosis

Always perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure.

Cylinder Deactivation Data

To provide maximum fuel economy under light load driving conditions, the engine control module (ECM) will command the displacement on demand (DoD) system ON to deactivate engine cylinders 1 and 7 on the left bank, and cylinders 4 and 6 on the right bank, switching to V4 mode. The DoD system consists of an electro-hydraulic actuator device called the VLOM assembly. All 4 VLOM solenoids are connected in parallel to a fused ignition 1 voltage circuit supplied by the powertrain relay. The ground or control circuit for each solenoid is connected to an individual low side driver internal to the ECM. When all enabling conditions for V4 mode are met, the ECM will command the low side driver to turn ON, grounding each VLOM solenoid control circuit in engine firing order sequence.

1. This test procedure requires that the vehicle battery has passed a load test and is completely charged.
2. When disconnecting electrical connectors or removing fuses and relays from a fuse block, always inspect the electrical terminals for corrosion and the mating electrical terminals for tightness.
3. Use the J 35616 GM Approved Terminal Test Kit for any test that requires probing the underhood fuse block, electrical components, wire harness, or the ECM wire harness connector terminals.

Engine Controls Schematics

Connector End View Reference

1. «Engine Control Module (ECM) Connector End Views»(/pontiac/grand-prix/vii-2004-2008/remont/testing-diagnostics/#engine-controls-53l-introduction-2-of-2__engine-control-module-ecm-connector-end)
2. «Engine Controls Connector End Views»(/pontiac/grand-prix/vii-2004-2008/remont/testing-diagnostics/#engine-controls-53l-introduction-2-of-2__engine-controls-connector-end-views)
3. «Electrical Center Identification Views»(/pontiac/grand-prix/vii-2004-2008/remont/electrical-component-locations/#wiring-systems-component-views)

Electrical Information Reference

1. «Circuit Testing»(/pontiac/grand-prix/vii-2004-2008/remont/body-electrical/#how-to-diagnosis-repair-the-wiring-systems-testing__circuit-testing)
2. «Connector Repairs»(/pontiac/grand-prix/vii-2004-2008/remont/body-electrical/#how-to-diagnosis-repair-the-wiring-systems-testing__connector-repairs)
3. «Testing for Intermittent Conditions and Poor Connections»(/pontiac/grand-prix/vii-2004-2008/remont/body-electrical/#how-to-diagnosis-repair-the-wiring-systems-testing__testing-for-intermittent-conditions-and-poor)
4. «Wiring Repairs»(/pontiac/grand-prix/vii-2004-2008/remont/body-electrical/#how-to-diagnosis-repair-the-wiring-systems-testing__wiring-repairs)

Mechanical Information Reference

Displacement on Demand (DoD) System Diagnosis

Scan Tool Reference

1. «Scan Tool Data List»(/pontiac/grand-prix/vii-2004-2008/remont/testing-diagnostics/#engine-controls-53l-introduction-1-of-2__scan-tool-data-list)
2. «Scan Tool Data Definitions»(/pontiac/grand-prix/vii-2004-2008/remont/testing-diagnostics/#engine-controls-53l-introduction-1-of-2__scan-tool-data-definitions)
3. «Scan Tool Output Controls»(/pontiac/grand-prix/vii-2004-2008/remont/testing-diagnostics/#engine-controls-53l-introduction-1-of-2__scan-tool-output-controls)

Special Tools Required

1. EN-46999 Displacement On Demand Tester
2. J 23738-A Mityvac. See «Special Tools»(/pontiac/grand-prix/vii-2004-2008/remont/testing-diagnostics/#engine-controls-53l-introduction-2-of-2__special-tools) .

1. If DTC P1101 is set, refer to «Displacement on Demand (DoD) System Diagnosis»(/pontiac/grand-prix/vii-2004-2008/remont/mechanical/#engine-mechanical-53l__displacement-on-demand-dod-system-diagnosis) .
2. With the ignition ON and the engine OFF, command each VLOM solenoid ON and OFF several times using the scan tool Output Control function. You should be able to hear the solenoid energize and de-energized with each scan tool output control command.

1. Connect a vacuum gage to the evaporative emission (EVAP) vacuum tube fitting on the intake manifold. Do not use a compound pressure and vacuum gage. The vacuum gage on a hand held vacuum pump or Mityvac will work fine for this test.
2. Allow the engine to reach normal operating temperature.
3. With a scan tool, command each DoD solenoid ON, one at a time. Each time a DoD solenoid is commanded ON, you should observe a fluctuating drop of 0.5-2 inches of Hg or vacuum on the gage. The drop in vacuum occurs because both the intake and exhaust valves are deactivated for that cylinder. Also, the engine will have a misfire when that cylinder is deactivated. For additional DoD mechanical testing, refer to «Displacement on Demand (DoD) System Diagnosis»(/pontiac/grand-prix/vii-2004-2008/remont/mechanical/#engine-mechanical-53l__displacement-on-demand-dod-system-diagnosis) .
4. Clear any DTCs with a scan tool.
5. With a scan tool, monitor the following parameters in the Cylinder Deactivation Data menu: The Cylinder Deactivation System command The Cylinder #1, 4, 6, and 7 Deactivation Solenoid command The Cylinder Deactivation Performance test
6. Road test the vehicle at 40 mph, under a light load condition with a steady throttle input that will allow V4 mode. The scan tool should display V4 mode for the Cylinder Deactivation System command, ON for each Cylinder Deactivation Solenoid command, and OK for the Cylinder Deactivation Performance test. If the engine does not switch to V4 mode, then review the DoD inhibit fault listing at the end of the Cylinder Deactivation Data menu, or refer to «Displacement on Demand (DoD) System Description»(/pontiac/grand-prix/vii-2004-2008/remont/testing-diagnostics/#engine-controls-53l-introduction-2-of-2__displacement-on-demand-dod-system-description) for inhibit reasons. If the engine does switch to V4 mode, review the DoD driving information in the Features and Controls section of the owner's manual with the vehicle operator, or instruct the vehicle operator in the proper driving techniques to obtain V4 mode.

1. With the ignition OFF, disconnect the VLOM wire harness electrical connector. Connect the cable that is labeled POWER from the DoD tester to the electrical connector on the VLOM assembly. Connect both the positive and the negative power leads of the DoD tester to the respective battery terminals at the battery. Command each VLOM solenoid ON and OFF several times using the DoD tester. You should be able to hear the solenoids being energized and de-energized with each ON and OFF command. If you cannot hear each solenoid being energized, replace the VLOM assembly.
2. Disconnect the cable that is labeled POWER from the VLOM assembly. Connect the cable that is labeled RESISTANCE to the VLOM assembly. Connect the test leads from a DMM to the resistance test ports on the DoD tester. Set the DMM to measure resistance and zero out the DMM display. Press and hold each solenoid switch pad for solenoids #1 through #4, one at a time, on the DoD tester. Monitor the DMM display. If each solenoid does not measure within 11-18 ohms of resistance, replace the VLOM assembly.
3. Remove one DMM test lead from the DoD tester. Connect the DMM test lead to a good ground on the engine. Press and hold each solenoid switch pad for solenoids #1 through #4, one at a time, on the DoD tester. Monitor the DMM display. If continuity or resistance is detected for any VLOM solenoid, replace the VLOM assembly.

1. «Valve Lifter Oil Manifold Replacement»(/pontiac/grand-prix/vii-2004-2008/remont/mechanical/#engine-mechanical-53l)
2. «Control Module References»(/pontiac/grand-prix/vii-2004-2008/remont/communication-devices/#computerintegrating-systems__control-module-references) for replacement, setup, and programming

Repair Verification

1. Install any components or connectors that have been removed or replaced during diagnosis.
2. Perform any adjustment, programming, or setup procedures that are required when a component or module is removed or replaced.
3. Clear the DTCs.
4. Turn OFF the ignition for 60 seconds. If the repair was related to a DTC, duplicate the condition for running the DTC and use the Freeze Frame/Failure Records, if applicable, in order to verify the DTC does not reset. If the DTC resets or another DTC is present, refer to «Diagnostic Trouble Code (DTC) List - Vehicle»(/pontiac/grand-prix/vii-2004-2008/remont/oem-general-information/#vehicle-dtc-information__diagnostic-trouble-code-dtc-list) and perform the appropriate diagnostic procedure. OR If the repair was symptom related, duplicate the conditions under which the customer concern occurred to verify the repair. If the customer concerns reoccurs, return to «Symptoms - Vehicle»(/pontiac/grand-prix/vii-2004-2008/remont/oem-general-information/#vehicle-dtc-information) and perform the appropriate symptom diagnostic.

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

Conditions for Updating the I/M System Status

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

For example, when the HO2S Heater Status indicates YES, either all of the oxygen sensor heater tests have passed or one of the tests has illuminated the MIL. If the vehicle has 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.

Monitored Emission Control Systems

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

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

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

Inspection/Maintenance (I/M) System Check

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

I/M Data List

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

Conditions for Meeting a Cold Start

1. The ignition voltage between 11-18 volts.
2. The barometric pressure (BARO) is more than 75 kPa.
3. The start-up engine coolant temperature (ECT) is between 4-30°C (39-86°F).
4. The start-up intake air temperature (IAT) is between 4-30°C (39-86°F).
5. The difference between the IAT and the ECT is 6°C (10.8°F)
6. The ambient air temperature is between 4-30°C (39-86°F).
7. Fuel level is between 15-85 percent

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

Inspection/Maintenance (I/M) System Set Procedure

1. Ensure that the vehicle meets the conditions for a cold start listed above. If the evaporative emission (EVAP) I/M System Status indicator displays NO, perform the EVAP Service bay test if available. If the EVAP Service bay test is NOT available, it may take up to 6 drive cycles, with up to 17 hours between drive cycles, for the EVAP I/M System Status indicator to transition to YES. If the O2S Heater System Status indicator displays NO, ensure that the ignition has been turned OFF for at least 10 hours.
2. Set the vehicle parking brake and ensure the vehicle is in park for automatic transmission or neutral for manual transmission.
3. Turn OFF all accessories; HVAC system, other electrical loads, including aftermarket/add-on equipment, etc.
4. Start and idle the engine for at least 2 minutes and until 65°C (149°F) is achieved.
5. Run the engine for 6.5 minutes within the following conditions: MAF parameter between 4-30 g/s Engine speed steady between 1000-3000 RPM
6. Return the engine to idle for 1 minute.
7. Apply and hold brake pedal, and shift to Drive for automatic, or apply clutch pedal for manual and operate the vehicle within the following conditions for 2 minutes: Depress the accelerator pedal until throttle position (TP) sensor angle is more than 2 percent. Mass air flow (MAF) signal between 15-30 g/s RPM steady between 1200-2000 RPM
8. Tip: Do NOT touch the accelerator pedal during the idle period. A change in TP Sensor angle or an increase in engine speed may invalidate this portion of the test. Release the accelerator pedal and shift the vehicle to Park for automatic, or Neutral and release clutch pedal for manual, and allow the engine to idle for 2 minutes.
9. Quickly depress the accelerator pedal until TP Sensor Angle is more than 8 percent and return to idle, repeat 3 times.
10. Allow engine to idle for at least 2 minutes.
11. Release the parking brake and drive vehicle at 24 km/h (15 mph) or slower for 2 minutes.
12. Continue to drive the vehicle for at least 5.5 miles between 45-112 km/h (28-70 mph) with the vehicle reaching at least 80 km/h (50 mph).
13. Release the accelerator pedal for at least 2 seconds. This will allow the vehicle to enter decel fuel cut-off.
14. Depress the accelerator pedal until the TP Sensor angle is increased 3-20 percent and maintain a safe speed for 1 minute.
15. Safely stop the vehicle, with the engine in drive for automatic or in neutral with the clutch pedal depressed and parking brake applied for manual, idle for 2 minutes.
16. Shift to Park for automatic and apply the parking brake, or neutral and release clutch pedal for manual.
17. Turn OFF the ignition and exit the vehicle. Do NOT disturb the vehicle for 60 minutes.
18. Observe the Inspection/Maintenance (I/M) System Status with a scan tool. All of the I/M System Status indicators should display YES. If the EVAP I/M System Status indicator displays NO, turn OFF the ignition for 17 hours, ensure that the vehicle meets the conditions for a cold start, and repeat steps 12-18 six more times, or until the EVAP I/M System Status indicator transitions to YES. If the indicator continues to display NO, refer to the «Inspection/Maintenance (I/M) System DTC Table»(/pontiac/grand-prix/vii-2004-2008/remont/testing-diagnostics/#engine-controls-53l-troubleshooting__inspectionmaintenance-im-system-dtc-table) to identify the DTCs that did not run. Follow the Conditions for Running the DTC in order to set the EVAP I/M System Status indicator

1. If any of the I/M System Status indicators display NO, refer to the «Inspection/Maintenance (I/M) System DTC Table»(/pontiac/grand-prix/vii-2004-2008/remont/testing-diagnostics/#engine-controls-53l-troubleshooting__inspectionmaintenance-im-system-dtc-table) for the indicator which did not display YES. The I/M System DTC Table identifies the DTCs associated with each I/M System Status Indicator. Follow the Conditions for Running the DTC in order to set the associated status indicator.

Inspection/Maintenance (I/M) System DTC Table

Inspection/Maintenance (I/M) System DTC Table

See also:
• Diagnostic System Check - Vehicle
• Scan Tool Data List
• Connector Repairs
• Testing for Intermittent Conditions and Poor Connections
• Engine Controls Schematics
• Power and Grounding Component Views
• Temperature vs Resistance
• Circuit Testing
• Spark Plug Inspection
• Oil Consumption Diagnosis
• Engine Compression Test
• Cylinder Head Cleaning and Inspection
• Camshaft and Bearings Cleaning and Inspection
• Piston, Connecting Rod, and Bearings Cleaning and Inspection
• Crankshaft and Bearings Cleaning and Inspection
• Heated Oxygen and Oxygen Sensor Notice
• Exhaust Leakage
• DTC P0300
• Engine Overheating
• Restricted Exhaust
• Torque Converter Diagnosis Procedure
• Loss of Coolant
• Cooling Fan Inoperative
• Wiring Repairs
• Thermostat Diagnosis (Overheating)
• Thermostat Diagnosis (Slow to Heat)
• Charging System Test
• Crankcase Ventilation System Inspection/Diagnosis
• Symptoms - Instrument Panel, Gages and Console
• Brakes Drag
• Engine Control Module (ECM) Connector End Views
• Control Module References
• Diagnostic Trouble Code (DTC) List - Vehicle
• Battery Inspection/Test
• Engine Cranks Slowly
• Engine Controls Connector End Views
• DTC P0106
• Scan Tool Data Definitions
• Scan Tool Output Controls
• Diagnostic Repair Verification
• Relay Replacement (Within an Electrical Center)
• Engine Control Module Programming and Setup
• Probing Electrical Connectors
• Fuel Pressure Relief Procedure
• Testing for Continuity
• Special Tools
• Lifting and Jacking the Vehicle
• Fuel System Cleaning
• Spark Plug Wire Inspection
• Displacement on Demand (DoD) System Diagnosis
• Displacement on Demand (DoD) System Description
• Road Test Caution
• DTC P0446
• Hard Start
• Surges/Chuggles
• Lack of Power, Sluggishness, or Sponginess
• Detonation/Spark Knock
• Hesitation, Sag, Stumble
• Cuts Out, Misses
• Poor Fuel Economy
• Poor Fuel Fill Quality
• Rough, Unstable, or Incorrect Idle and Stalling
• Dieseling, Run-On
• Backfire
• Symptoms - Engine Controls
• Inspection/Maintenance (I/M) System DTC Table