Engine Controls - System & Component Testing - 3.4l Chevrolet Monte Carlo VI

INTRODUCTION

Before testing separate components or systems, perform all procedures listed in BASIC DIAGNOSTIC PROCEDURES - 3.4L ALERO, GRAND AM, IMPALA & MONTE CARLO article. Since many computer-controlled and monitored components will set a DTC if they malfunction, it is also recommended self-diagnostics be performed. See DIAGNOSTIC STARTING POINT- ENGINE CONTROLS under SELF-DIAGNOSTIC SYSTEM in SELF-DIAGNOSTICS - 3.4L ALERO, GRAND AM, IMPALA & MONTE CARLO article.

Note. Testing individual components does not isolate shorts or opens. Perform all voltage tests using a DVOM with a minimum 10-megohm input impedance, unless stated otherwise in test procedure. Use ohmmeter to isolate wiring harness shorts or opens.

COMPONENT LOCATIONS

To aid in component locations, refer to illustrations. See COMPONENT LOCATIONS in SELF-DIAGNOSTICS - 3.4L ALERO, GRAND AM, IMPALA & MONTE CARLO article.

COMPONENT LOCATIONS (ALERO & GRAND AM)

COMPONENT LOCATIONS (ALERO & GRAND AM)

COMPONENT LOCATIONS (IMPALA & MONTE CARLO)

COMPONENT LOCATIONS (IMPALA & MONTE CARLO)

AIR INDUCTION SYSTEMS

Note. A malfunction in air induction systems circuit can set a DTC. For testing procedures and specifications, perform related DTC testing procedure. See DIAGNOSTIC TROUBLE CODE DEFINITIONS in SELF-DIAGNOSTICS - 3.4L ALERO, GRAND AM, IMPALA & MONTE CARLO article.

Note. For circuit reference, see WIRING DIAGRAMS . For component locations, see COMPONENT LOCATIONS . For connector identification, see CONNECTOR IDENTIFICATION in SELF-DIAGNOSTICS - 3.4L ALERO, GRAND AM, IMPALA & MONTE CARLO article.

COMPUTERIZED ENGINE CONTROLS

Note. For circuit reference, see WIRING DIAGRAMS . For component locations, see COMPONENT LOCATIONS . For connector identification, see CONNECTOR IDENTIFICATION in SELF-DIAGNOSTICS - 3.4L ALERO, GRAND AM, IMPALA & MONTE CARLO article.

POWERTRAIN CONTROL MODULE

Note. To identify circuits, see WIRING DIAGRAMS .

Poor power or ground connections can cause widely varying symptoms. For additional diagnostic and repair procedures, see INTERMITTENTS in TROUBLE SHOOTING - 3.4L ALERO, GRAND AM, IMPALA & MONTE CARLO article.

Ground Circuits

1. Using DVOM, check for continuity to ground at PCM ground terminals. For connector terminal identification, see «CONNECTOR IDENTIFICATION»(/chevrolet/monte-carlo/vi-1999-2007/remont/testing-diagnostics/#engine-controls-self-diagnostics-34l) in SELF-DIAGNOSTICS - 3.4L ALERO, GRAND AM, IMPALA & MONTE CARLO article. See «WIRING DIAGRAMS»(/chevrolet/monte-carlo/vi-1999-2007/remont/testing-diagnostics/#engine-controls-system-component-testing-34l) . Circuit resistance should be less than 5 ohms. If resistance is not less than 5 ohms, repair open in ground circuit.
2. Connect negative lead of DVOM to a known-good ground. Backprobe positive lead of voltmeter to each PCM ground terminal. With vehicle running, DVOM should indicate less than one volt. If DVOM reading is greater than one volt, check for open, short to voltage, corrosion or loose connection in ground circuit.

Power Circuits

1. Using DVOM, check for battery voltage between PCM continuous power terminal(s) and ground. For connector terminal identification, see «CONNECTOR IDENTIFICATION»(/chevrolet/monte-carlo/vi-1999-2007/remont/testing-diagnostics/#engine-controls-self-diagnostics-34l) in SELF-DIAGNOSTICS - 3.4L ALERO, GRAND AM, IMPALA & MONTE CARLO article. See «WIRING DIAGRAMS»(/chevrolet/monte-carlo/vi-1999-2007/remont/testing-diagnostics/#engine-controls-system-component-testing-34l) . If battery voltage is not present, check for open fuse or fusible link. If fuse or fusible link is okay, check for open in circuit between PCM continuous power terminal and power source.
2. Turn ignition switch to RUN position. Using DVOM, check for battery voltage between PCM ignition power terminals and ground. If battery voltage is not present, check IGN fuse. If fuse is okay, check for open in circuit between battery and ignition switch, and between ignition switch and PCM ignition power terminal. If circuits are okay, check for defective ignition switch.
3. Connect DVOM between ground and PCM starter (crank) signal terminal. On vehicles with manual transaxle, depress clutch pedal. On vehicles with automatic transaxle, place gearshift lever in Park. On all models, turn ignition switch to START position. Battery voltage should be present only when ignition switch is in START position.
4. If voltage is not present, check CRANK fuse (10-amp) or fusible link between ignition switch and PCM starter (crank) signal terminal. If fuse or fusible link is okay, check for open in circuit between ignition switch and PCM starter (crank) signal terminal, or check for defective ignition switch.

PCM Harness Resistance

Turn ignition switch to LOCK position. Disconnect PCM and related component harness connectors. Check for open or short circuits between PCM harness connector terminal and component harness connector terminal. For connector terminal identification, see CONNECTOR IDENTIFICATION in SELF-DIAGNOSTICS - 3.4L ALERO, GRAND AM, IMPALA & MONTE CARLO article. See WIRING DIAGRAMS . If harness is open or shorted, repair as necessary.

SENSORS & SWITCHES

Note. For additional sensor testing specifications, see appropriate SENSOR OPERATING RANGE CHARTS article.

Note. Perform powertrain diagnostic system check - engine controls prior to testing, and after completing any repairs. See DIAGNOSTIC SYSTEM CHECK - ENGINE CONTROLS in SELF-DIAGNOSTICS - 3.4L ALERO, GRAND AM, IMPALA & MONTE CARLO article.

Manufacturer does not provide testing procedures for many individual systems and components. For sensor and switch testing not listed, perform related DTC testing procedure. See SELF-DIAGNOSTICS - 3.4L ALERO, GRAND AM, IMPALA & MONTE CARLO article.

Note. For circuit reference, see WIRING DIAGRAMS . For component locations, see COMPONENT LOCATIONS . For connector identification, see CONNECTOR IDENTIFICATION in SELF-DIAGNOSTICS - 3.4L ALERO, GRAND AM, IMPALA & MONTE CARLO article.

A/C REFRIGERANT PRESSURE SENSOR

A malfunction in A/C Refrigerant Pressure sensor circuit can set a DTC. For testing procedures and specifications, perform related DTC testing procedure. See DIAGNOSTIC TROUBLE CODE DEFINITIONS in SELF-DIAGNOSTICS - 3.4L ALERO, GRAND AM, IMPALA & MONTE CARLO article.

AUTOMATIC TRANSMISSION INPUT SHAFT SPEED SENSOR

See appropriate DIAGNOSIS article in AUTOMATIC TRANSMISSIONS.

CAMSHAFT POSITION SENSOR

A malfunction in Camshaft Position (CMP) sensor circuit can set a DTC. For testing procedures and specifications, perform related DTC testing procedure. See DIAGNOSTIC TROUBLE CODE DEFINITIONS in SELF-DIAGNOSTICS - 3.4L ALERO, GRAND AM, IMPALA & MONTE CARLO article.

CRANKSHAFT POSITION SENSOR (7X & 24X)

A malfunction in Crankshaft Position (CKP) sensor circuit can set a DTC. For testing procedures and specifications, perform related DTC testing procedure. See DIAGNOSTIC TROUBLE CODE DEFINITIONS in SELF-DIAGNOSTICS - 3.4L ALERO, GRAND AM, IMPALA & MONTE CARLO article.

ENGINE COOLANT TEMPERATURE SENSOR

A malfunction in Engine Coolant Temperature (ECT) sensor circuit can set a DTC. For testing procedures and specifications, perform related DTC testing procedure. See DIAGNOSTIC TROUBLE CODE DEFINITIONS in SELF-DIAGNOSTICS - 3.4L ALERO, GRAND AM, IMPALA & MONTE CARLO article.

EXHAUST GAS RECIRCULATION VALVE POSITION SENSOR

A malfunction in Exhaust Gas Recirculation Position (EGR) sensor circuit can set a DTC. For testing procedures and specifications, perform related DTC testing procedure. See DIAGNOSTIC TROUBLE CODE DEFINITIONS in SELF-DIAGNOSTICS - 3.4L ALERO, GRAND AM, IMPALA & MONTE CARLO article.

FUEL LEVEL SENSOR

A malfunction in fuel level sensor circuit can set a DTC. For testing procedures and specifications, perform related DTC testing procedure. See DIAGNOSTIC TROUBLE CODE DEFINITIONS in SELF-DIAGNOSTICS - 3.4L ALERO, GRAND AM, IMPALA & MONTE CARLO article.

FUEL TANK PRESSURE SENSOR

A malfunction in Fuel Tank Pressure (FTP) sensor circuit can set a DTC. For testing procedures and specifications, perform related DTC testing procedure. See DIAGNOSTIC TROUBLE CODE DEFINITIONS in SELF-DIAGNOSTICS - 3.4L ALERO, GRAND AM, IMPALA & MONTE CARLO article.

HEATED OXYGEN SENSOR

A malfunction in Heated Oxygen Sensor (HO2S) circuit can set a DTC. For testing procedures and specifications, perform related DTC testing procedure. See DIAGNOSTIC TROUBLE CODE DEFINITIONS in SELF-DIAGNOSTICS - 3.4L ALERO, GRAND AM, IMPALA & MONTE CARLO article.

INTAKE AIR TEMPERATURE SENSOR

A malfunction in Intake Air Temperature (IAT) sensor circuit can set a DTC. For testing procedures and specifications, perform related DTC testing procedure. See DIAGNOSTIC TROUBLE CODE DEFINITIONS in SELF-DIAGNOSTICS - 3.4L ALERO, GRAND AM, IMPALA & MONTE CARLO article.

KNOCK SENSOR

A malfunction in Knock Sensor (KS) circuit can set a DTC. For testing procedures and specifications, perform related DTC testing procedure. See DIAGNOSTIC TROUBLE CODE DEFINITIONS in SELF-DIAGNOSTICS - 3.4L ALERO, GRAND AM, IMPALA & MONTE CARLO article.

MANIFOLD ABSOLUTE PRESSURE SENSOR

A malfunction in Manifold Absolute Pressure (MAP) sensor circuit can set a DTC. For testing procedures and specifications, perform related DTC testing procedure. See DIAGNOSTIC TROUBLE CODE DEFINITIONS in SELF-DIAGNOSTICS - 3.4L ALERO, GRAND AM, IMPALA & MONTE CARLO article.

MASS AIR FLOW SENSOR

A malfunction in Mass Air Flow (MAF) sensor circuit can set a DTC. For testing procedures and specifications, perform related DTC testing procedure. See DIAGNOSTIC TROUBLE CODE DEFINITIONS in SELF-DIAGNOSTICS - 3.4L ALERO, GRAND AM, IMPALA & MONTE CARLO article.

PARK NEUTRAL POSITION SWITCH

See appropriate DIAGNOSIS article in AUTOMATIC TRANSMISSIONS for testing procedures.

THROTTLE POSITION SENSOR

A malfunction in Throttle Position (TP) sensor circuit can set a DTC. For testing procedures and specifications, perform related DTC testing procedure. See DIAGNOSTIC TROUBLE CODE DEFINITIONS in SELF-DIAGNOSTICS - 3.4L ALERO, GRAND AM, IMPALA & MONTE CARLO article.

VEHICLE SPEED SENSOR

A malfunction in Vehicle Speed Sensor (VSS) circuit can set a DTC. For testing procedures and specifications, perform related DTC testing procedure. See DIAGNOSTIC TROUBLE CODE DEFINITIONS in SELF-DIAGNOSTICS - 3.4L ALERO, GRAND AM, IMPALA & MONTE CARLO article.

MOTORS, RELAYS & SOLENOIDS

Note. Manufacturer does not provide testing procedures for many individual systems and components. For module, motor, relay and solenoid testing not listed, perform related DTC testing procedure. See SELF-DIAGNOSTICS - 3.4L ALERO, GRAND AM, IMPALA & MONTE CARLO article.

Note. For circuit reference, see WIRING DIAGRAMS . For component locations, see COMPONENT LOCATIONS . For connector identification, see CONNECTOR IDENTIFICATION in SELF-DIAGNOSTICS - 3.4L ALERO, GRAND AM, IMPALA & MONTE CARLO article.

A/C COMPRESSOR CLUTCH RELAY

See appropriate MANUAL or AUTOMATIC A/C-HEATER SYSTEMS article in AIR CONDITIONING & HEATING.

EVAP CANISTER PURGE SOLENOID

A malfunction in EVAP canister purge solenoid circuit can set a DTC. For testing procedures and specifications, perform related DTC testing procedure. See DIAGNOSTIC TROUBLE CODE DEFINITIONS in SELF-DIAGNOSTICS - 3.4L ALERO, GRAND AM, IMPALA & MONTE CARLO article.

EVAP CANISTER VENT SOLENOID

A malfunction in EVAP canister vent solenoid circuit can set a DTC. For testing procedures and specifications, perform related DTC testing procedure. See DIAGNOSTIC TROUBLE CODE DEFINITIONS in SELF-DIAGNOSTICS - 3.4L ALERO, GRAND AM, IMPALA & MONTE CARLO article.

FUEL PUMP RELAY

Fuel pump relay is located in underhood fuse/relay block. To test fuel pump relay, see FUEL PUMP ELECTRICAL CIRCUIT DIAGNOSIS under FUEL SYSTEMS.

IDLE AIR CONTROL VALVE

Note. Perform powertrain diagnostic system check prior to testing, and after completing any repairs. See DIAGNOSTIC SYSTEM CHECK - ENGINE CONTROLS in SELF-DIAGNOSTICS - 3.4L ALERO, GRAND AM, IMPALA & MONTE CARLO article.

Note. For circuit reference, see WIRING DIAGRAMS . For component locations, see COMPONENT LOCATIONS . For connector identification, see CONNECTOR IDENTIFICATION in SELF-DIAGNOSTICS - 3.4L ALERO, GRAND AM, IMPALA & MONTE CARLO article.

Circuit Description

The engine idle speed is controlled by the Idle Air Control (IAC) valve. The IAC valve is on the throttle body. The IAC valve pintle moves in and out of an idle air passage bore to control air flow around the throttle plate. The IAC valve consists of a movable pintle, driven by a gear attached to an electric motor called a stepper motor. The stepper motor is capable of highly accurate rotation, or of movement, called steps. The stepper motor has 2 separate windings that are called coils. Each coil is supplied current by two circuits from the Powertrain Control Module (PCM). When the PCM changes polarity of a coil, the stepper motor moves one step. The PCM uses a predetermined number of counts to determine the IAC pintle position. Observe IAC counts using a scan tool. The IAC counts will increment up or down as the PCM attempts to change the IAC valve pintle position. An IAC reset will occur when the ignition key is turned OFF. First, the PCM will seat the IAC pintle in the idle air passage bore. Second, the PCM will retract the pintle a predetermined number of counts to allow for efficient engine start-up. If the engine idle speed is out of range for a calibrated period of time, an idle speed Diagnostic Trouble Code (DTC) sets.

Test Description

The numbers below refer to the step numbers in the diagnostic procedures.

1. 5 - This test determines the ability of the PCM and IAC valve circuits to control the IAC valve.
2. 7 - This test determines the ability of the PCM to provide the IAC valve circuits with a ground. On a normally operating system, the test light should not flash while the IAC counts are incrementing.

Diagnostic Procedures

1. Perform diagnostic system check - engine controls. See «DIAGNOSTIC SYSTEM CHECK - ENGINE CONTROLS»(/chevrolet/monte-carlo/vi-1999-2007/remont/testing-diagnostics/#engine-controls-self-diagnostics-34l) in SELF-DIAGNOSTICS - 3.4L ALERO, GRAND AM, IMPALA & MONTE CARLO article. After performing diagnostic system check - engine controls, go to next step.
2. Set parking brake and block drive wheels. Install scan tool. Start the engine. Turn all accessories OFF. Using scan tool RPM control function, slowly increment engine speed to 1700 RPM, then to 600 RPM. Then to 1700 RPM. Exit RPM control function. Did the ENGINE SPEED parameter stabilize within 100 RPM less than the commanded engine speed or within 150 RPM above the commanded RPM? If yes, see «DIAGNOSTIC AIDS»(/chevrolet/monte-carlo/vi-1999-2007/remont/testing-diagnostics/#engine-controls-system-component-testing-34l__diagnostic-aids) . If no, go to next step.
3. Turn ignition switch to OFF position. Disconnect IAC valve harness connector. Connect IAC System Motor Driver (J 37027-A) to IAC valve. Start the engine. Using IAC system motor analyzer, command IAC valve in until about 600 RPM is reached and then command IAC valve out until about 1700 RPM is reached. Return engine RPM to desired idle as indicated on scan tool data list. Did the ENGINE SPEED parameter steadily decrease to 600 RPM and steadily increase to 1700 RPM when the IAC valve was commanded in and out? If yes, go to step 5 . If no, go to next step.
4. Did you observe an excessively high idle condition that could not be controlled with the IAC motor driver during the last test? If yes, go to step 11 . If no, go to step 12 .
5. Using a test light connected to ground, probe one IAC valve circuit at the IAC valve harness connector. See «WIRING DIAGRAMS»(/chevrolet/monte-carlo/vi-1999-2007/remont/testing-diagnostics/#engine-controls-system-component-testing-34l) . Start the engine. Using IAC system motor analyzer, command low RPM while observing scan tool until IAC counts start to increment, then command high RPM until IAC counts start to increment. Observe test light while incrementing IAC counts. Return engine to idle as indicated on scan tool data list. Repeat procedure for other three IAC valve circuits. Did the test light remain ON, never flashing, while the IAC counts were incrementing for any of the IAC valve control circuits? If yes, go to step 10 . If no, go to next step.
6. Did the test light remain OFF, never flashing, while the IAC counts were incrementing for any of the IAC valve control circuits? If yes, go to step 9 . If no, go to next step.
7. Using Connector Test Adapter Kit (J 35616-A) connect a test light between IAC coil "A" low circuit and IAC coil "A" high circuit at IAC valve harness connector. Using IAC system motor driver, command low RPM while observing scan tool until IAC counts start to increment, then command high RPM until IAC counts start to increment. Observe test light while incrementing IAC counts. Return engine speed to desired idle as indicated on scan tool data list. Repeat procedure on IAC coil "B" low circuit and IAC coil "B" high circuit. Did the test light stay illuminated, never flashing, while the IAC counts were incrementing? If yes, go to next step. If no, go to step 17 .
8. Check for an intermittent and for a poor connection at the IAC valve harness connector. Did you find and correct the condition? If yes, go to step 18 . If no, go to step 13 .
9. Turn ignition switch to OFF position. Disconnect PCM harness connectors. Using a DMM, test the circuit where the test light remained off for the following: An open circuit. A short to ground. A short to another IAC valve circuit. Did you find and correct the condition? If yes, go to step 18 . If no, go to step 13 .
10. Turn ignition switch to RUN position, engine OFF. Using a DMM, test the circuit where the test light remained illuminated for the following: A short to voltage. A short to another IAC valve circuit. Did you find and correct the condition? If yes, go to step 18 . If no, go to step 13 .
11. Visually and physically inspect for the following: Throttle body damage and tampering. Skewed TP sensor signal. Throttle lever screw tampering (if equipped). Vacuum leaks. Faulty, incorrectly installed PCV valve and hose (if equipped). Throttle shaft binding. Throttle linkage or cruise control linkage binding (if equipped). Remove IAC valve. Check for the following: Clogged IAC passage. Excessive deposits on throttle plate. Excessive deposits in throttle bore. Excessive deposits on IAC valve pintle. Did you find and correct the condition? If yes, go to step 18 . If no, go to step 15 .
12. Visually and physically inspect for the following: Throttle body damage and tampering. Throttle lever screw tampering (if equipped). Restricted air intake system. A possible collapsed or clogged air intake duct, before and after the air filter element. A restricted air filter element. Restriction at the throttle body intake screen, if equipped. Excessive deposits on throttle plate. Excessive deposits in throttle bore. Remove IAC valve and inspect for excessive deposits on IAC valve pintle and in IAC valve passage. Repair as necessary. Did you find and correct the condition? If yes, go to step 18 . If no, go to step 15 .
13. Check for poor PCM harness connections. Did you find and correct the condition? If yes, go to step 18 . If no, go to next step.
14. Disconnect the PCM harness connectors. Using a DMM, test all IAC valve circuits for high resistance. Did you find and correct the condition? If yes, go to step 18 . If no, go to step 17 .
15. Check for poor IAC valve harness connection. Did you find and correct the condition? If yes, go to step 18 . If no, go to next step.
16. Replace IAC valve. After repair, go to step 18 .
17. Replace the PCM. See POWERTRAIN CONTROL MODULE in appropriate REMOVAL & INSTALLATION article. Perform PCM relearn procedure. See «POWERTRAIN CONTROL MODULE»(/chevrolet/monte-carlo/vi-1999-2007/remont/testing-diagnostics/#engine-controls-self-diagnostics-34l) under PROGRAMMING in SELF-DIAGNOSTICS - 3.4L ALERO, GRAND AM, IMPALA & MONTE CARLO article.
18. Reconnect any disconnected components. Use the scan tool to clear any DTCs that may have set. Turn ignition switch to OFF position for 30 seconds. Operate the vehicle to verify the repair. Did you correct the condition? If yes, go to next step. If no, go to step 2 .
19. Using a scan tool, observe the stored information in Capture Info. Does the scan tool display any DTCs that you have not diagnosed? If yes, see «DIAGNOSTIC TROUBLE CODE DEFINITIONS»(/chevrolet/monte-carlo/vi-1999-2007/remont/testing-diagnostics/#engine-controls-self-diagnostics-34l__diagnostic-trouble-code-definitions) in SELF-DIAGNOSTICS - 3.4L ALERO, GRAND AM, IMPALA & MONTE CARLO article. If no, system is okay at this time.

Diagnostic Aids

Check for the following conditions

1. High resistance in an IAC valve control circuit.
2. The correct Positive Crankcase Ventilation (PCV) valve, properly installed and proper operation of the PCV valve.
3. Proper operation and installation of all air intake components.
4. Proper installation and operation of the Mass Air Flow (MAF) sensor, if equipped.
5. A tampered with or damaged throttle stop screw.
6. A tampered with or damaged throttle plate, throttle shaft, throttle linkage, or cruise control linkage, if equipped.
7. A skewed high Throttle Position (TP) sensor.
8. Excessive deposits in the IAC passage or on the IAC pintle.
9. Excessive deposits in the throttle bore or on the throttle plate.
10. Vacuum leaks.
11. A high or unstable idle condition could be caused by a non-IAC system problem that can not be overcome by the IAC valve. Go to «SYMPTOM DIAGNOSIS - ENGINE CONTROLS»(/chevrolet/monte-carlo/vi-1999-2007/remont/testing-diagnostics/#engine-controls-trouble-shooting-no-codes-34l__symptom-diagnosis-engine-controls) under SYMPTOMS in TROUBLE SHOOTING - 3.4L ALERO, GRAND AM, IMPALA & MONTE CARLO article.
12. If the problem is determined to be intermittent, go to «INTERMITTENTS»(/chevrolet/monte-carlo/vi-1999-2007/remont/testing-diagnostics/#engine-controls-trouble-shooting-no-codes-34l__intermittents) in SELF-DIAGNOSTICS - 3.4L ALERO, GRAND AM, IMPALA & MONTE CARLO article.

IGNITION RELAY

For testing procedures and specifications, go to IGNITION RELAY DIAGNOSIS under IGNITION SYSTEMS.

FUEL SYSTEMS

Manufacturer does not provide testing procedures for many individual systems and components. For fuel system testing not listed, perform related DTC testing procedure. See SELF-DIAGNOSTICS - 3.4L ALERO, GRAND AM, IMPALA & MONTE CARLO article.

Note. Perform powertrain diagnostic system check - engine controls prior to testing, and after completing any repairs. See DIAGNOSTIC SYSTEM CHECK - ENGINE CONTROLS in SELF-DIAGNOSTICS - 3.4L ALERO, GRAND AM, IMPALA & MONTE CARLO article.

Note. For circuit reference, see WIRING DIAGRAMS . For component location, see COMPONENT LOCATIONS . For connector identification, see CONNECTOR IDENTIFICATION in SELF-DIAGNOSTICS - 3.4L ALERO, GRAND AM, IMPALA & MONTE CARLO article.

FUEL SYSTEM PRESSURE RELEASE

1. Disconnect the negative battery cable.
2. Install the Fuel Pressure Gauge Adaptor (J 34730-262), or equivalent, to the fuel pressure connection, located on the fuel rail.
3. Place the fuel pressure gauge bleed hose into an approved gasoline container.
4. Open the valve to bleed the system pressure. The fuel connections are now safe for servicing.
5. Disconnect the fuel pressure gauge from the fuel pressure connection and install the fuel pressure port cap.

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 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 Fuel Composition Tester (J 44175) and Instruction Manual (J44175-3), or equivalents.
2. If water appears in the fuel sample, clean the fuel system. Go to «FUEL SYSTEM CLEANING»(/chevrolet/monte-carlo/vi-1999-2007/remont/testing-diagnostics/#engine-controls-system-component-testing-34l__fuel-system-cleaning) and/or replace the fuel filter as necessary.
3. Subtract 50 from the reading on the DMM to obtain the percentage of alcohol in the fuel sample. See the examples in the «FUEL COMPOSITION TEST EXAMPLES»(/chevrolet/monte-carlo/vi-1999-2007/remont/testing-diagnostics/#engine-controls-system-component-testing-34l) 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. Go to «FUEL SYSTEM CLEANING»(/chevrolet/monte-carlo/vi-1999-2007/remont/testing-diagnostics/#engine-controls-system-component-testing-34l__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 rail, 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. Fuel contaminated with alcohol may cause driveability conditions such as hesitation, lack of power, stalling, or no start. Some types of alcohol are more detrimental to fuel system components than others.

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, use the following procedure to test the fuel quality

1. Fill the cylinder with fuel to the 90 ml mark using a 100 ml specified cylinder with 1 ml graduation marks.
2. Add 10 ml of water 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 to release the pressure.
5. 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 to allow adequate liquid separation.

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. Draw approximately 0.5 liter of fuel using an approved fuel container.
2. Place the cylinder on a level surface for approximately 5 minutes to allow settling of the particulate contamination.

Particulate contamination will show up in various shapes and colors. Sand will typically be identified by white or light brown crystals. Rubber will appear as Black and irregular particles. If particles are found, clean the entire fuel system thoroughly. Go to FUEL SYSTEM CLEANING .

Fuel System Overview

The fuel tank stores the fuel supply. An electric fuel pump, located in the fuel tank with the fuel sender assembly, pumps fuel through an in-line fuel filter to the fuel rail assembly. The pump provides fuel at a pressure more than is needed by the injectors. The fuel pressure regulator, part of the fuel rail assembly, keeps fuel available to the injectors at a regulated pressure. A separate pipe returns unused fuel to the fuel tank.

FUEL INJECTOR BALANCE TEST WITH SPECIAL TOOL

Note. For circuit reference, see WIRING DIAGRAMS . For component location, see COMPONENT LOCATIONS . For connector identification, see CONNECTOR IDENTIFICATION in SELF-DIAGNOSTICS - 3.4L ALERO, GRAND AM, IMPALA & MONTE CARLO article.

The scan tool is first used to energize the fuel pump relay. 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. (Scheme 73) See FUEL INJECTOR BALANCE TEST EXAMPLE (TYPICAL).

FUEL INJECTOR BALANCE TEST EXAMPLE (TYPICAL)

Scheme 73

The numbers below refer to the step numbers in the diagnostic procedure.

1. 3 - The Engine Coolant Temperature (ECT) must be below the operating temperature to avoid irregular fuel pressure readings due to hot soak fuel boiling.
2. 6 - If the pressure drop value for each fuel injector is within 1.5 psi (10 kPa) of the average pressure drop value, the fuel injectors are flowing properly.

1. Perform diagnostic system check - engine controls. See «DIAGNOSTIC SYSTEM CHECK - ENGINE CONTROLS»(/chevrolet/monte-carlo/vi-1999-2007/remont/testing-diagnostics/#engine-controls-self-diagnostics-34l) in SELF-DIAGNOSTICS - 3.4L ALERO, GRAND AM, IMPALA & MONTE CARLO article. After performing diagnostic system check - engine controls, go to next step.
2. Did you perform the Fuel Injector Coil Test? If yes, go to next step. If no, perform fuel injector coil test. Go to «FUEL INJECTOR COIL TEST»(/chevrolet/monte-carlo/vi-1999-2007/remont/testing-diagnostics/#engine-controls-system-component-testing-34l__fuel-injector-circuit-diagnosis) .
3. Observe the ECT parameter on the scan tool. Does the scan tool indicate that the ECT parameter is less than 201°F (94°C)? If yes, go to next step. If no, allow engine to cool below 201°F (94°C), then go to next step.
4. Turn ignition switch to OFF position. Install the Fuel Pressure Gauge (J 34730-1A) and the fuel pressure gauge fitting. Turn ignition switch to RUN position, engine OFF. Command the fuel pump ON using a scan tool. You may need to command the fuel pump ON a few times, to obtain the highest possible fuel pressure. Do NOT start the engine. Observe the fuel pressure gauge, with the fuel pump commanded ON. Is the fuel pressure 52-59 psi (358-405 kPa)? If yes, go to next step. If no, go to «FUEL SYSTEM DIAGNOSIS»(/chevrolet/monte-carlo/vi-1999-2007/remont/testing-diagnostics/#engine-controls-system-component-testing-34l__fuel-system-diagnosis) .
5. Monitor the fuel pressure gauge for one minute. Does the fuel pressure decrease by more than 5 psi (34 kPa)? If yes, go to «FUEL SYSTEM DIAGNOSIS»(/chevrolet/monte-carlo/vi-1999-2007/remont/testing-diagnostics/#engine-controls-system-component-testing-34l__fuel-system-diagnosis) . If no, go to next step.
6. Connect the Fuel Injector Coil/Balancer Tester (J 39021), Injector Selector Switch box (J 39021-210), and Fuel Injector Test Harness (J 39021-410, or equivalents to the fuel injector multi-way harness connector. Set the amperage supply selector switch on the fuel injector tester to the BALANCE TEST 0.5-2.5 AMP position. Command the fuel pump ON and then OFF using a scan tool. Record the fuel pressure indicated by the fuel pressure gauge after the fuel pressure stabilizes. This is the first pressure reading. Record the fuel pressure value immediately after the fuel injector stops pulsing. The fuel pressure may rise after the fuel injector stops pulsing. Do NOT record the higher fuel pressure value. Energize the fuel injector by depressing the PUSH TO START TEST button on the fuel injector tester. Record the fuel pressure indicated by the fuel pressure gauge. This is the second fuel pressure reading. Repeat procedure for each fuel injector. Subtract the second pressure reading from the first pressure reading for one fuel injector. The result is the pressure drop value. Obtain a pressure drop value for each fuel injector. Add all of the individual pressure drop values. This is the total pressure drop. Divide the total pressure drop by the number of fuel injectors. This is the average pressure drop. Does any fuel injector have a pressure drop value that is more than the average pressure drop or less than the average pressure drop by 1.5 psi (10 kPa)? If yes, go to next step. If no, go to «SYMPTOM DIAGNOSIS - ENGINE CONTROLS»(/chevrolet/monte-carlo/vi-1999-2007/remont/testing-diagnostics/#engine-controls-trouble-shooting-no-codes-34l__symptom-diagnosis-engine-controls) under SYMPTOMS in TROUBLE SHOOTING - 3.4L ALERO, GRAND AM, IMPALA & MONTE CARLO article.
7. Clean the fuel injectors. Go to «FUEL INJECTOR CLEANING»(/chevrolet/monte-carlo/vi-1999-2007/remont/testing-diagnostics/#engine-controls-system-component-testing-34l__fuel-injector-cleaning) . After cleaning, go to next step.
8. Operate the vehicle to verify the repair. Does a driveability condition still exist? If yes, go to «SYMPTOM DIAGNOSIS - ENGINE CONTROLS»(/chevrolet/monte-carlo/vi-1999-2007/remont/testing-diagnostics/#engine-controls-trouble-shooting-no-codes-34l__symptom-diagnosis-engine-controls) under SYMPTOMS in TROUBLE SHOOTING - 3.4L ALERO, GRAND AM, IMPALA & MONTE CARLO article. If no, system is okay at this time.

FUEL INJECTOR BALANCE TEST WITH TECH 2

Note. For circuit reference, see WIRING DIAGRAMS . For component locations, see COMPONENT LOCATIONS . For connector identification, see CONNECTOR IDENTIFICATION in SELF-DIAGNOSTICS - 3.4L ALERO, GRAND AM, IMPALA & MONTE CARLO article.

The scan tool first energizes the fuel pump and then the injectors 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.

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

1. 3 - The Engine Coolant Temperature (ECT) must be below the operating temperature to avoid irregular fuel pressure readings due to hot soak fuel boiling.
2. 6 - If the pressure drop value for each fuel injector is within 1.5 psi (10 kPa) of the average pressure drop value, the fuel injectors are flowing properly.

Diagnostic Procedure

1. Perform diagnostic system check - engine controls. See «DIAGNOSTIC SYSTEM CHECK - ENGINE CONTROLS»(/chevrolet/monte-carlo/vi-1999-2007/remont/testing-diagnostics/#engine-controls-self-diagnostics-34l) in SELF-DIAGNOSTICS - 3.4L ALERO, GRAND AM, IMPALA & MONTE CARLO article. After performing diagnostic system check - engine controls, go to next step.
2. Did you perform the fuel injector coil test? If yes, go to next step. If no, go to «FUEL INJECTOR COIL TEST»(/chevrolet/monte-carlo/vi-1999-2007/remont/testing-diagnostics/#engine-controls-system-component-testing-34l__fuel-injector-coil-test) .
3. Observe the ECT parameter using a scan tool. Does the scan tool indicate that the ECT parameter is less than 201°F (94°C)? If yes, go to next step.
4. Turn ignition switch to OFF position. Turn all accessories OFF. Install the Fuel Pressure Gauge (J 34730-1A), or equivalent, to the fuel pressure gauge fitting. Turn ignition switch to RUN position, engine OFF. Command the fuel pump ON using a scan tool. You may need to command the fuel pump ON a few times to obtain the highest possible fuel pressure. Do not start the engine. Observe the fuel pressure gauge with the fuel pump commanded ON. Is the fuel pressure 52-59 psi (358-405 kPa)? If no, go to next step. If no, go to «FUEL SYSTEM DIAGNOSIS»(/chevrolet/monte-carlo/vi-1999-2007/remont/testing-diagnostics/#engine-controls-system-component-testing-34l__fuel-system-diagnosis) .
5. Observe the fuel pressure gauge for one minute. Does the fuel pressure drop more than 5 psi (34 kPa)? If yes, go to «FUEL SYSTEM DIAGNOSIS»(/chevrolet/monte-carlo/vi-1999-2007/remont/testing-diagnostics/#engine-controls-system-component-testing-34l__fuel-system-diagnosis) . If no, go to next step.
6. Using a scan tool, select the FUEL INJECTOR BALANCE TEST function, within the SPECIAL FUNCTIONS menu. Select an injector to be tested. Press ENTER. This will prime the fuel system. Record the fuel pressure indicated by the fuel pressure gauge after the fuel pressure stabilizes. This is the first pressure reading. Record the fuel pressure value immediately after the fuel injector stops pulsing. The fuel pressure may rise after the fuel injector stops pulsing. Do not record the higher fuel pressure value. Energize the fuel injector by depressing the PULSE INJECTOR button on the scan tool. This will energize the injector and decrease the fuel pressure. Record the fuel pressure indicated by the fuel pressure gauge after the fuel injector has stopped pulsing. This is the second pressure reading. Press ENTER again to bring you back to the SELECT INJECTOR screen. Repeat for each fuel injector. Subtract the second pressure reading from the first pressure reading for one fuel injector. The result is the pressure drop value. Obtain a pressure drop value for each fuel injector. Add all of the individual pressure drop values. This is the total pressure drop. Divide the total pressure drop by the number of fuel injectors. This is the average pressure drop. Does any fuel injector have a pressure drop value that is either higher than the average pressure drop or lower than the average pressure drop by 1.5 psi (10 kPa)? If yes, go to next step. If no, go to «SYMPTOM DIAGNOSIS - ENGINE CONTROLS»(/chevrolet/monte-carlo/vi-1999-2007/remont/testing-diagnostics/#engine-controls-trouble-shooting-no-codes-34l__symptom-diagnosis-engine-controls) under SYMPTOMS in TROUBLE SHOOTING - 3.4L ALERO, GRAND AM, IMPALA & MONTE CARLO article.
7. Clean the fuel injectors. Go to «FUEL INJECTOR CLEANING»(/chevrolet/monte-carlo/vi-1999-2007/remont/testing-diagnostics/#engine-controls-system-component-testing-34l__fuel-injector-cleaning) . After cleaning, go to next step.
8. Operate the vehicle to verify the repair. Does a driveability condition still exist? If yes, go to «SYMPTOM DIAGNOSIS - ENGINE CONTROLS»(/chevrolet/monte-carlo/vi-1999-2007/remont/testing-diagnostics/#engine-controls-trouble-shooting-no-codes-34l__symptom-diagnosis-engine-controls) under SYMPTOMS in TROUBLE SHOOTING - 3.4L ALERO, GRAND AM, IMPALA & MONTE CARLO article. If no, system is okay at this time.

FUEL INJECTOR CIRCUIT DIAGNOSIS

Note. For circuit reference, see WIRING DIAGRAMS . For component locations, see COMPONENT LOCATIONS . For connector identification, see CONNECTOR IDENTIFICATION in SELF-DIAGNOSTICS - 3.4L ALERO, GRAND AM, IMPALA & MONTE CARLO article.

The Powertrain Control Module (PCM) enables the appropriate fuel injector on the intake stroke for each cylinder. A voltage is supplied directly to the fuel injectors. The PCM controls each fuel injector by grounding the control circuit via a solid state device called a driver.

The numbers below refer to the step numbers in the diagnostic procedure.

1. 4 - This step tests for a short to ground on the fuel injector ignition 1 voltage supply circuit.
2. 5 - This step tests for a short to a PCM ground on the fuel injector ignition 1 voltage supply circuit.
3. 6 - This step tests for an open between the multi-way connector and the fuel injectors.
4. 7 - This step tests for an open or high resistance between the multi-way connector and the fuel injectors.

1. Perform diagnostic system check - engine controls. See «DIAGNOSTIC SYSTEM CHECK - ENGINE CONTROLS»(/chevrolet/monte-carlo/vi-1999-2007/remont/testing-diagnostics/#engine-controls-self-diagnostics-34l) in SELF-DIAGNOSTICS - 3.4L ALERO, GRAND AM, IMPALA & MONTE CARLO article. After performing diagnostic system check - engine controls, go to next step.
2. Are any fuel injector DTCs set? If yes, go to «DTC P0201-P0206: INJECTOR CONTROL CIRCUIT»(/chevrolet/monte-carlo/vi-1999-2007/remont/testing-diagnostics/#engine-controls-self-diagnostics-34l__dtc-p0201-p0206-injector-control-circuit) under DIAGNOSTIC TESTS in SELF-DIAGNOSTICS - 3.4L ALERO, GRAND AM, IMPALA & MONTE CARLO article. If yes, go to step 4. If no, go to next step.
3. Check the fuel injector fuse (15-amp), located in the bottom underhood junction block. (Scheme 74) Is the fuel injector fuse open? If yes, go to next step. If no, go to step 6.
4. Turn ignition switch to OFF position. Disconnect the fuel injector multi-way harness connector. Probe the fuel injector ignition 1 voltage circuit, fuse side, using a test light connected to battery voltage. Does the test light illuminate? If yes, go to step 9. If no, go to next step.
5. Turn ignition switch to RUN position, engine OFF. Does the test light illuminate? If yes, go to step 13. If no, go to step 8.
6. Turn ignition switch to OFF position. Disconnect the fuel injector multi-way harness connector. Turn ignition switch to RUN position, engine OFF. Probe the fuel injector ignition 1 voltage circuit, fuse side, using a test light connected to a good ground. Does the test light illuminate? If yes, go to next step. If no, go to step 10.
7. Test for continuity between the ignition voltage terminal and a fuel injector terminal, at the multi-way harness connector, fuel injector side. Does the DMM display a resistance above 5 ohms? If yes, go to step 11. If no, go to step 12.
8. Test the fuel injector ignition 1 voltage circuit, between the multi-way harness connector and the fuel injectors for a short to ground. Did you find and correct the condition? If yes, go to step 14. If no, go to «INTERMITTENTS»(/chevrolet/monte-carlo/vi-1999-2007/remont/testing-diagnostics/#engine-controls-trouble-shooting-no-codes-34l__intermittents) in TROUBLE SHOOTING - 3.4L ALERO, GRAND AM, IMPALA & MONTE CARLO article.
9. Repair the short to ground in the fuel injector ignition voltage circuit. After repair, go to step 14.
10. Repair the open in the ignition 1 voltage between UBEC and the multi-way connector. After repair, go to step 14.
11. Repair the fuel injectors ignition 1 voltage circuit for an open and/or high resistance, between the multi-way connector and the splice. After repair, go to step 14.
12. Repair the poor connection at the multi-way connector. After repair, go to step 14.
13. Repair the short to a PCM ground in the fuel injector ignition voltage circuit. After repair, go to step 14.
14. Operate the system to verify the repair. Did you correct the condition? If yes, system is okay at this time. If no, go to step 3.

Scheme 74

Monitoring misfire current counters, or misfire graph, may help isolate fuel injector causing condition.

Operating vehicle over a wide temperature range may help isolate fuel injector causing condition.

Perform fuel injector coil test within conditions of customers concern. A fuel injector condition may only be apparent at a certain temperature, or under certain conditions. If fuel injector coil test does not isolate condition perform fuel injector balance test. See FUEL INJECTOR BALANCE TEST .

FUEL INJECTOR CLEANING

Cleaning Procedure

1. Obtain Fuel Injector Cleaner (J 38500-A), or equivalent. Ensure the shut-off valve at the bottom of the canister is closed. (Scheme 75)
2. For US dealers, empty 2 pre-measured GM Top-Engine Cleaner (GM P/N 12346535) containers, 0.812 oz. (24 ml) each, into the fuel injector cleaner.
3. For Canadian dealers, measure and dispense 1.62 oz. (48 ml) of Top-Engine Cleaner, (Canadian P/N 992872), into the fuel injector cleaner.
4. If you are using any other brand of tank you will need a total of 3.24 oz. (96 ml) of Top-Engine Cleaner mixed with 29.16 oz. (864 ml) of regular unleaded gasoline.
5. Fill the injector cleaning tank with regular unleaded gasoline. Be sure to follow all additional instructions provided with the tool.
6. Electrically disable the vehicle fuel pump by removing the fuel pump relay, located in the upper underhood fuse block, and disconnecting the oil pressure switch connector, if equipped. (Scheme 76)
7. Disconnect the fuel feed and return lines at the fuel rail. Plug the fuel feed and return lines coming off the fuel rail using the appropriate Fuel Line Shut Off Adapter (J 37287 or J 42964-1 and J 42964-2 or J 42873-1 and J 42873-2), or equivalents, as appropriate for the fuel system.
8. Connect the fuel injector cleaner to the vehicle's fuel rail.
9. Pressurize the fuel injector cleaner to 75 psi (510 kPa).
10. Start and idle the engine until it stalls, due to lack fuel. This should take approximately 15-20 minutes.
11. Disconnect fuel injector cleaner from the fuel rail.
12. Reconnect the vehicle's fuel pump relay and oil pressure switch connector, if equipped.
13. Remove fuel line shut-off adapter and reconnect the vehicles fuel feed and return lines.
14. Start and idle the vehicle for an additional 2 minutes to ensure residual injector cleaner is flushed from the fuel rail and fuel lines.
15. Repeat steps 1-5 of the appropriate Injector Balance Test, and record the fuel pressure drop from each injector.
16. Subtract the lowest fuel pressure drop from the highest fuel pressure drop. If the value is 2 psi (15 kPa) or less, no additional action is required. If the value is greater than 2 psi (15 kPa), replace the injector with the lowest fuel pressure drop.
17. Add one ounce of Port Fuel Injector Cleaner (GM P/N 12345104, Canadian P/N 10953467), to the vehicles fuel tank for each gallon of gasoline estimated to be in the fuel tank. Instruct the customer to add the reminder of the bottle of Port Fuel Injector Cleaner to the vehicle fuel tank at the next fill-up.
18. Advise the customer to change brands of fuel and to add GM Port Fuel Injector Cleaner every 3000 miles. GM Port Fuel Injector Cleaner contains the same additives that the fuel companies are removing from the fuel to reduce costs. Regular use of GM Port Fuel Injector Cleaner should keep the customer from having to repeat the injector cleaning procedure.
19. Road test the vehicle to verify that the customer concern has been corrected.

Scheme 75

Scheme 76

FUEL INJECTOR COIL TEST

Note. For circuit reference, see WIRING DIAGRAMS . For component locations, see COMPONENT LOCATIONS . For connector identification, see CONNECTOR IDENTIFICATION in SELF-DIAGNOSTICS - 3.4L ALERO, GRAND AM, IMPALA & MONTE CARLO article.

The Powertrain Control Module (PCM) enables the appropriate fuel injector on the intake stroke for each cylinder. Ignition voltage is supplied directly to the fuel injectors. The PCM 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 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 fuel injector coil windings resistance will increase as the temperature of the fuel injector increases.

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

1. 3 - This step tests each fuel injector resistance within a specific temperature range. If any of the fuel injectors display a resistance outside of the specified value, replace the fuel injector.
2. 4 - This step determines if all of the fuel injectors are within 3 ohms of each other. If the highest resistance value is within 3 ohms of the lowest resistance value, then all of the fuel injector coil windings are okay.
3. 6 - This step determines if the ignition 1 voltage circuit under the intake plenum is causing the concern.
4. 8 - This step determines which fuel injector is faulty. After subtracting the highest and lowest resistance values from the average value, replace the fuel injector that has the greatest resistance difference from the average.

1. Perform diagnostic system check - engine controls. See «DIAGNOSTIC SYSTEM CHECK - ENGINE CONTROLS»(/chevrolet/monte-carlo/vi-1999-2007/remont/testing-diagnostics/#engine-controls-self-diagnostics-34l) in SELF-DIAGNOSTICS - 3.4L ALERO, GRAND AM, IMPALA & MONTE CARLO article. After performing diagnostic system check - engine controls, go to next step.
2. Observe the Engine Coolant Temperature (ECT) using a scan tool. Is the ECT value 50-90°F (10-32°C)? If yes, go to next step. If no, go to step 4 .
3. Disconnect the fuel injector multi-way harness connector. Measure the resistance of each fuel injector between the ignition feed circuit and the fuel injector control circuit, at the multi-way connector using a DMM. Do any of the fuel injectors display a resistance outside 11-14 ohms? If yes, go to step 5 . If no, go to «DIAGNOSTIC AIDS»(/chevrolet/monte-carlo/vi-1999-2007/remont/testing-diagnostics/#engine-controls-system-component-testing-34l) .
4. Disconnect the fuel injector multi-way connector. Measure the resistance of each fuel injector between the ignition feed circuit and the fuel injector control circuit, at the multi-way connector using a DMM. Record each fuel injector value. Subtract the lowest resistance value from the highest resistance value. Is the difference equal to, or less than, 3 ohms? If yes, go to «FUEL INJECTOR BALANCE TEST WITH SPECIAL TOOL»(/chevrolet/monte-carlo/vi-1999-2007/remont/testing-diagnostics/#engine-controls-system-component-testing-34l__fuel-injector-balance-test-with-special) or «FUEL INJECTOR BALANCE TEST WITH TECH 2»(/chevrolet/monte-carlo/vi-1999-2007/remont/testing-diagnostics/#engine-controls-system-component-testing-34l__fuel-injector-balance-test-with-tech) . If no, go to step 8 .
5. Remove the upper intake manifold. Go to appropriate article in ENGINES. Did you complete the action? If yes, go to next step.
6. Measure the resistance of the ignition 1 voltage circuit between the multi-way connector and the affected fuel injector connector, using a DMM. Is the resistance more than 5 ohms? If yes, go to next step. If no, go to step 9 .
7. Repair the open or high resistance in the ignition 1 voltage circuit. After repair, go to step 11 .
8. 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 and the highest individual fuel injector resistance values from the average resistance value. Replace the fuel injector that displays the greatest resistance difference, above or below the average. After repair, go to step 11 .
9. Test for an intermittent and for a poor connection at the affected fuel injector. Did you find and correct the condition? If yes, go to step 11 . If no, go to next step.
10. Replace any fuel injectors that measured out of specification. After repair, go to step 11 .
11. Operate the system to verify the repair. Did you correct the condition? If yes, system is okay at this time. If no, go to step 2 .

1. Monitoring the misfire current counters, or misfire graph, may help isolate the fuel injector causing the condition.
2. Operating the vehicle over a wide temperature range may help isolate the fuel injector 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.
4. If the fuel injector coil test does not isolate the condition perform the fuel injector balance test. Go to «FUEL INJECTOR BALANCE TEST WITH SPECIAL TOOL»(/chevrolet/monte-carlo/vi-1999-2007/remont/testing-diagnostics/#engine-controls-system-component-testing-34l__fuel-injector-balance-test-with-special) or «FUEL INJECTOR BALANCE TEST WITH TECH 2»(/chevrolet/monte-carlo/vi-1999-2007/remont/testing-diagnostics/#engine-controls-system-component-testing-34l__fuel-injector-balance-test-with-tech) .

FUEL PUMP ELECTRICAL CIRCUIT DIAGNOSIS (ALERO & GRAND AM)

Note. For circuit reference, see WIRING DIAGRAMS . For component locations, see COMPONENT LOCATIONS . For connector identification, see CONNECTOR IDENTIFICATION in SELF-DIAGNOSTICS - 3.4L ALERO, GRAND AM, IMPALA & MONTE CARLO article.

When the ignition switch is turned to RUN position, the Powertrain Control Module (PCM) enables the fuel pump relay which powers the fuel pump ON. The fuel pump remains ON as long as the engine is cranking or running and the PCM receives ignition reference pulses. If there are no ignition reference pulses, the PCM shuts the fuel pump OFF within 2 seconds after the ignition was switched to the RUN position or if the engine stops.

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

1. 2 - Command both the ON and OFF states. Repeat the commands as necessary.
2. 3 - This step determines if the condition is located on the coil side or the switch side of the circuit.
3. 4 - This step verifies that the PCM is providing voltage to the fuel pump relay.
4. 5 - This step tests for an open in the ground circuit to the fuel pump relay.
5. 6 - This step determines if a voltage is constantly being applied to the fuel pump relay.
6. 12 - This tests for a grounded voltage supply circuit. The FP-INJR fuse (15-amp) supplies power to fuel pump and the fuel injectors. Disconnecting the fuel pump in-line harness connector isolates the fuel pump voltage supply circuit.
7. 15 - This step jumps the fuel pump relay to activate the fuel pump.
8. 17 - This step tests for an open or high resistance in the fuel pump ground circuit.
9. 20 - This step determines if the condition with the circuit is intermittent. If the fuse does not open, inspect the supply voltage circuit between the fuse and the fuel pump for an intermittent condition.

1. Perform diagnostic system check - engine controls. See «DIAGNOSTIC SYSTEM CHECK - ENGINE CONTROLS»(/chevrolet/monte-carlo/vi-1999-2007/remont/testing-diagnostics/#engine-controls-self-diagnostics-34l) in SELF-DIAGNOSTICS - 3.4L ALERO, GRAND AM, IMPALA & MONTE CARLO article. After performing diagnostic system check - engine controls, go to next step.
2. Install a scan tool. Turn ignition switch to RUN position, engine OFF. Using a scan tool, command the fuel pump relay ON and OFF. Does the fuel pump turn ON and OFF? If yes, go to «INTERMITTENTS»(/chevrolet/monte-carlo/vi-1999-2007/remont/testing-diagnostics/#engine-controls-trouble-shooting-no-codes-34l__intermittents) in TROUBLE SHOOTING - 3.4L ALERO, GRAND AM, IMPALA & MONTE CARLO article. If no, go to next step.
3. Using a scan tool, command the fuel pump relay ON and OFF. Do you hear a click when you command the fuel pump relay ON and OFF? If yes, go to step 9 . If no, go to next step.
4. Turn ignition switch to OFF position. Disconnect the fuel pump relay. Turn ignition switch to RUN position, engine OFF. Probe the fuel pump relay control circuit using a test light connected to a good ground. Using a scan tool, command the fuel pump ON and OFF. Does the test light turn ON and OFF? If yes, go to next step. If no, go to step 6 .
5. Connect the test light between the fuel pump relay control circuit and the fuel pump relay ground circuit. Using a scan tool, command the fuel pump ON and OFF. Does the test light turn ON and OFF? If yes, go to step 21 . If no, go to step 24 .
6. Does the test light remain illuminated with each command? If yes, go to next step. If no, go to step 8 .
7. Test the fuel pump relay control circuit for a short to voltage. Did you find and correct the condition? If yes, go to step 29 . If no, go to step 28 .
8. Test the fuel pump relay control circuit for a short to ground or an open. Did you find and correct the condition? If yes, go to step 29 . If no, go to step 22 .
9. Turn ignition switch to RUN position, engine OFF. Does the fuel pump operate continuously? If yes, go to next step. If no, go to step 11 .
10. Turn ignition switch to OFF position. Disconnect the fuel pump relay. Turn ignition switch to RUN position, engine OFF. Does the fuel pump operate continuously? If yes, go to step 23 . If no, go to step 27 .
11. Is the FP-INJR fuse open? If yes, go to next step. If no, go to step 14 .
12. Disconnect the fuel pump harness in-line connector, located near the fuel tank. Test the fuel pump and the fuel injectors supply voltage circuit for a grounded circuit. Replace the FP-INJR fuse if necessary. Did you find and correct the condition? If yes, go to step 29 . If no, go to next step.
13. Lower the fuel tank if necessary. Test or inspect the fuel tank electrical harness for the following: Damage to the harness. A grounded circuit. Replace the FP-INJR fuse if necessary. Did you find and correct the condition? If yes, go to step 29 . If no, go to step 20 .
14. Turn ignition switch to OFF position. Disconnect the fuel pump relay. Turn ignition switch to RUN position, engine OFF. Probe the fuel pump relay ignition 1 voltage circuit using a test light connected to a good ground. Does the test light illuminate? If yes, go to next step. If no, go to step 25 .
15. Connect a 10-amp fused jumper wire between the ignition 1 voltage circuit and the fuel pump supply voltage circuit in the fuel pump cavity. Does the fuel pump operate? If yes, go to step 21 . If no, go to next step.
16. Disconnect the fuel pump harness in-line connector located near the fuel tank. Test the fuel pump supply voltage circuit for an open or high resistance between the fuel pump relay and the in-line connector. Did you find and correct the condition? If yes, go to step 29 . If no, go to next step.
17. Check the ground circuit for being tight, corrosion on the terminals, or damage to the wiring harness. Test the fuel pump ground circuit for an open or high resistance between the body pass through connector and ground. If yes, go to step 29 . If no, go to next step.
18. Check for poor connections at the fuel pump in-line connector to the body pass through connector. Did you find and correct the condition? If yes, go to step 29 . If no, go to next step.
19. Lower the fuel tank. Test or inspect the fuel tank harness for the following: Damage to the harness. An open circuit. Did you find and correct the condition? If yes, go to step 29 . If no, go to step 26 .
20. Connect all disconnected components. Install a NEW fuel pump fuse. Using a scan tool, command the fuel pump ON. Is the fuel pump fuse open? If yes, go to step 29 . If no, go to «INTERMITTENTS»(/chevrolet/monte-carlo/vi-1999-2007/remont/testing-diagnostics/#engine-controls-trouble-shooting-no-codes-34l__intermittents) in TROUBLE SHOOTING - 3.4L ALERO, GRAND AM, IMPALA & MONTE CARLO article.
21. Check for poor connections at the fuel pump relay. Did you find and correct the condition? If yes, go to step 29 . If no, go to step 27 .
22. Check for poor connections at the PCM harness connector. Did you find and correct the condition? If yes, go to step 29 . If no, go to step 28 .
23. Repair short to voltage in the fuel pump supply voltage circuit. After repair, go to step 29 .
24. Repair open in the fuel pump relay ground circuit. After repair, go to step 29 .
25. Repair open in the fuel pump relay ignition 1 voltage circuit. After repair, go to step 29 .
26. Check for poor connections at the fuel pump, within the fuel tank, before replacing the fuel pump. Repair as necessary. If fuel pump connections are okay, replace the fuel pump. Replace the fuel pump fuse if necessary. After repair, go to step 29 .
27. Check the fuel pump prime circuit for a short to voltage. Repair as necessary. If fuel pump prime circuit is okay, replace the fuel pump relay. Did you complete the repair? If yes, go to step 29 .
28. Replace the PCM. See POWERTRAIN CONTROL MODULE in appropriate REMOVAL & INSTALLATION article. Perform PCM relearn procedure. See «POWERTRAIN CONTROL MODULE»(/chevrolet/monte-carlo/vi-1999-2007/remont/testing-diagnostics/#engine-controls-self-diagnostics-34l) under PROGRAMMING in SELF-DIAGNOSTICS - 3.4L ALERO, GRAND AM, IMPALA & MONTE CARLO article.
29. Operate the system to verify the repair. Did you correct the condition? If yes, system is okay at this time. If no, go to step 2 .

FUEL PUMP ELECTRICAL CIRCUIT DIAGNOSIS (IMPALA & MONTE CARLO)

Note. For circuit reference, see WIRING DIAGRAMS . For component locations, see COMPONENT LOCATIONS . For connector identification, see CONNECTOR IDENTIFICATION in SELF-DIAGNOSTICS - 3.4L ALERO, GRAND AM, IMPALA & MONTE CARLO article.

When the ignition switch is turned to RUN or CRANK position, the Powertrain Control Module (PCM) will turn ON the in-tank fuel pump. The in-tank fuel pump will remain ON as long as the engine is cranking or running and the PCM is receiving reference pulses. If there are no reference pulses, the PCM will turn the in-tank fuel pump OFF 2 seconds after the ignition is turned to RUN position or 2 seconds after the engine stops running.

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

1. 2 - Command both the ON and OFF states. Repeat the commands as necessary.
2. 3 - This step determines if the condition is located on the coil side or the switch side of the circuit.
3. 4 - This step verifies that the PCM is providing voltage to the fuel pump relay.
4. 5 - This step tests for an open in the ground circuit to the fuel pump relay.
5. 6 - This step determines if a voltage is constantly being applied to the fuel pump relay.
6. 13 - This step determines if the condition with the circuit is intermittent. If the fuse does not open, inspect the supply voltage circuit between the fuse and the fuel pump for an intermittent condition.
7. 15 - Use the same amperage fuse in the jumper that is used to protect the fuel pump circuit.
8. 17 - Check the ground connection for the fuel pump. Be certain all ground connections are clean and tight.

1. Perform diagnostic system check - engine controls. See «DIAGNOSTIC SYSTEM CHECK - ENGINE CONTROLS»(/chevrolet/monte-carlo/vi-1999-2007/remont/testing-diagnostics/#engine-controls-self-diagnostics-34l) in SELF-DIAGNOSTICS - 3.4L ALERO, GRAND AM, IMPALA & MONTE CARLO article. After performing diagnostic system check - engine controls, go to next step.
2. Install a scan tool. Turn ignition switch to RUN position, engine OFF. Using the scan tool, command the fuel pump relay ON and OFF. Does the fuel pump turn ON and OFF? If yes, go to «DIAGNOSTIC AIDS»(/chevrolet/monte-carlo/vi-1999-2007/remont/testing-diagnostics/#engine-controls-system-component-testing-34l) . If no, go to next step.
3. Using a scan tool, command the fuel pump relay ON and OFF. Do you hear a click when you command the fuel pump relay ON and OFF? If yes, go to step 9 . If no, go to next step.
4. Turn ignition switch to OFF position. Disconnect the fuel pump relay. Turn ignition switch to RUN position, engine OFF. Probe the fuel pump relay control circuit using a test light connected to a good ground. Using a scan tool, command the fuel pump relay ON and OFF. Does the test light turn ON and OFF? If yes, go to next step . If no, go to step 6 .
5. Connect a test light between the fuel pump relay control circuit and the fuel pump relay ground circuit. Using a scan tool, command the fuel pump relay ON and OFF. Does the test light turn ON and OFF? If yes, go to step 19 . If no, go to step 22 .
6. Does the test light remain illuminated with each command? If yes, go to next step. If no, go to step 8 .
7. Test the fuel pump relay control circuit for a short to voltage. Did you find and correct the condition? If yes, go to step 27 . If no, go to step 26 .
8. Test the fuel pump relay control circuit for a short to ground or an open. Did you find and correct the condition? If yes, go to step 27 . If no, go to step 20 .
9. Turn ignition switch to RUN position, engine OFF. Does the fuel pump operate continuously? If yes, go to next step. If no, go to step 11 .
10. Turn ignition switch to OFF position. Disconnect the fuel pump relay. Turn ignition switch to RUN position, engine OFF. Does the fuel pump operate continuously? If yes, go to step 21 . If no, go to step 13 .
11. Is the fuel pump fuse open? If yes, go to next step. If no, go to step 14 .
12. Test the fuel pump supply voltage circuit for a grounded circuit between the fuel pump fuse and the fuel pump. Replace the fuel pump fuse if necessary. Did you find and correct the condition? If yes, go to step 27 . If no, go to next step.
13. Install all disconnected electrical components. Install a new fuel pump fuse. Using a scan tool, turn ON the fuel pump. Is the fuel pump fuse open? If yes, go to step 27 . If no, go to go to «INTERMITTENTS»(/chevrolet/monte-carlo/vi-1999-2007/remont/testing-diagnostics/#engine-controls-trouble-shooting-no-codes-34l__intermittents) in TROUBLE SHOOTING - 3.4L ALERO, GRAND AM, IMPALA & MONTE CARLO article.
14. Turn ignition switch to OFF position. Disconnect the fuel pump relay. Turn ignition switch to RUN position, engine OFF. Probe the fuel pump relay switch battery voltage circuit using a test light connected to a good ground. Does the test light illuminate? If yes, go to step next step. If no, go to step 23 .
15. Connect a 20-amp fused jumper wire between the fuel pump relay switch battery voltage circuit and the fuel pump supply voltage circuit. Does the fuel pump operate? If yes, go to step 19 . If no, go to next step.
16. Test the fuel pump supply voltage circuit for an open or high resistance between the fuel pump relay and the fuel pump. Did you find and correct the condition? If yes, go to step 27 . If no, go to next step.
17. Test the fuel pump ground circuit for an open or high resistance. Did you find and correct the condition? If yes, go to step 27 . If no, go to next step.
18. Check for poor connections at the fuel pump. Did you find and correct the condition? If yes, go to step 27 . If no, go to step 24 .
19. Check for poor connections at the fuel pump relay. Did you find and correct the condition? If yes, go to step 27 . If no, go to step 25 .
20. Check for poor connections at the PCM harness connector. Did you find and correct the condition? If yes, go to step 27 . If no, go to step 26 .
21. Repair the fuel pump supply voltage circuit for a short to voltage. After repair, go to step 27 .
22. Repair the open fuel pump relay ground circuit. After repair, go to step 27 .
23. Repair the fuel pump relay switch battery voltage circuit. After repair, go to step 27 .
24. Replace the fuel pump. Replace the fuel pump fuse if necessary. After repair, go to step 27 .
25. Replace the fuel pump relay. After repair, go to step 27 .
26. Replace the PCM. See POWERTRAIN CONTROL MODULE in appropriate REMOVAL & INSTALLATION article. Perform PCM relearn procedure. See «POWERTRAIN CONTROL MODULE»(/chevrolet/monte-carlo/vi-1999-2007/remont/testing-diagnostics/#engine-controls-self-diagnostics-34l) under PROGRAMMING in SELF-DIAGNOSTICS - 3.4L ALERO, GRAND AM, IMPALA & MONTE CARLO article.
27. Operate the system to verify the repair. Did you correct the condition? If yes, system is okay at this time. If no, go to step 2 .

The following conditions may have caused the fuel pump fuse to open

1. The fuse is faulty.
2. There is an intermittent short in the fuel pump power feed circuit.
3. The fuel pump has an intermittent internal condition.

For an intermittent condition, go to INTERMITTENTS in TROUBLE SHOOTING - 3.4L ALERO, GRAND AM, IMPALA & MONTE CARLO article.

FUEL SYSTEM CLEANING

Note. If the fuel filter is plugged, the fuel tank should be inspected internally and cleaned if necessary.

Note. Cap the fittings and plug the holes when servicing the fuel system to prevent dirt and other contaminants from entering the open pipes and passages. Always maintain cleanliness when servicing fuel system components.

1. Remove the fuel tank.
2. Remove the fuel sender assembly.
3. Check the fuel pump inlet for dirt and debris. If dirt and debris are found, the fuel pump needs to be replaced.
4. Flush fuel tank with hot water.
5. Pour the water out of the fuel sender assembly opening in the fuel tank. Rock the fuel tank to be sure that the removal of the water from the fuel tank is complete.
6. Allow the fuel tank to dry completely before reassembly.
7. Disconnect the fuel pipes at the engine compartment fuel pipes.
8. Clean the fuel pipes by applying air pressure in the opposite direction of the fuel flow.
9. Connect the fuel pipes to the engine compartment fuel pipes.
10. Install the fuel sender assembly.
11. Install the fuel tank.
12. Replace the fuel filter.
13. Add fuel and install the fuel tank filler pipe cap.
14. Reconnect the negative battery cable.
15. Turn ignition switch to RUN position, engine OFF, for 2 seconds. Turn ignition switch to OFF position. Turn ignition switch to RUN position, engine OFF. Check for leaks.

FUEL SYSTEM DIAGNOSIS

Note. For circuit reference, see WIRING DIAGRAMS . For component locations, see COMPONENT LOCATIONS . For connector identification, see CONNECTOR IDENTIFICATION in SELF-DIAGNOSTICS - 3.4L ALERO, GRAND AM, IMPALA & MONTE CARLO article.

System Description

When the ignition is turned to RUN position, the Powertrain Control Module (PCM) will turn ON the in-tank fuel pump. The in-tank fuel pump will remain ON as long as the engine is cranking or running and the PCM is receiving ignition reference pulses. If there are no ignition reference pulses, the PCM will turn the in-tank fuel pump OFF 2 seconds after the ignition is turned ON or 2 seconds after the engine stops running.

The in-tank fuel pump is an electric pump attached to the fuel sender assembly. The fuel pump is designed to provide fuel at a pressure above the pressure needed by the fuel injectors. A fuel pressure regulator, attached to the fuel rail, keeps the fuel available to the fuel injectors at a regulated pressure. Unused fuel is returned to the fuel tank by a separate fuel return pipe.

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

1. 2 - This step verifies that the fuel pump is operating.
2. 4 - This step tests for an internal fuel leak. If the fuel pressure drops during this test, then an internal loss of pressure is indicated.
3. 6 - This step tests the fuel pressure regulator. The fuel pressure regulator is controlled by engine vacuum. With engine vacuum applied, the pressure should drop the specified value.
4. 9 - This step inspects the fuel pressure regulator for a fuel leak from the vacuum port. If fuel leaks from the fuel pressure regulator while the fuel pump is commanded ON, replace the fuel pressure regulator.
5. 10 - This step tests for a loss of fuel pressure between the fuel feed pipe shut-off adapter and the fuel pump.
6. 11 - This step tests for a leaking fuel injector, or fuel pressure regulator. If the fuel pressure remains constant during this test, the fuel injectors are not leaking fuel.
7. 14 - This step tests for a restricted fuel return pipe. If the fuel pressure is within the specified values, a restriction in the fuel return pipe is indicated.
8. 16 - This step determines if the fuel pressure regulator, or the fuel pump, is the cause of the low fuel pressure. If the pressure rises above the specified value, the fuel pump is okay.
9. 18 - This step verifies that a circuit condition is not the cause of a fuel pressure concern. Check all fuel pump electrical circuits thoroughly.

1. Perform diagnostic system check - engine controls. See «DIAGNOSTIC SYSTEM CHECK - ENGINE CONTROLS»(/chevrolet/monte-carlo/vi-1999-2007/remont/testing-diagnostics/#engine-controls-self-diagnostics-34l) in SELF-DIAGNOSTICS - 3.4L ALERO, GRAND AM, IMPALA & MONTE CARLO article. After performing diagnostic system check - engine controls, go to next step.
2. Turn ignition switch to RUN position, engine OFF. Command the fuel pump ON using a scan tool. Does the fuel pump operate? If yes, go to next step. If no, go to «FUEL PUMP ELECTRICAL CIRCUIT DIAGNOSIS»(/chevrolet/monte-carlo/vi-1999-2007/remont/testing-diagnostics/#engine-controls-system-component-testing-34l__fuel-pump-electrical-circuit-diagnosis-impala) .
3. Turn ignition switch to OFF position. Turn OFF all the accessories. Install a Fuel Pressure Gauge (J 34730-1A), or equivalent, and the fuel pressure gauge fitting. Turn ignition switch to RUN position, engine OFF. Command the fuel pump ON using a scan tool. The fuel pump runs for approximately 2 seconds. Command the fuel pump ON to obtain the highest possible fuel pressure. Do not start the engine. Observe the fuel pressure gauge, with the fuel pump commanded ON. Is the fuel pressure 52-59 psi (358-405 kPa)? If yes, go to next step. If no, go to step 12 .
4. Monitor the fuel pressure gauge for one minute Does the fuel pressure drop more than 5 psi (34 kPa)? If yes, go to step 9 . If no, go to next step.
5. Relieve the fuel pressure to 10 psi (69 kPa). Monitor the fuel pressure gauge for 5 minutes. Does the fuel pressure drop more than 2 psi (14 kPa)? If yes, go to step 24 . If no, go to next step.
6. Turn ignition switch to OFF position for 15 seconds. Turn ignition switch to RUN position, engine OFF. Monitor the fuel pressure gauge. Start the engine. Does the fuel pressure drop 3-10 psi (21-69 kPa) when the engine is started? If yes, go to next step. If no, go to step 8 .
7. Operate the vehicle within the conditions of the customer's concern. Monitor the fuel related parameters using a scan tool. Do any of the scan tool parameters indicate a lean condition? If yes, go to step 17 . If no, go to «SYMPTOM DIAGNOSIS - ENGINE CONTROLS»(/chevrolet/monte-carlo/vi-1999-2007/remont/testing-diagnostics/#engine-controls-trouble-shooting-no-codes-34l__symptom-diagnosis-engine-controls) under SYMPTOMS in TROUBLE SHOOTING - 3.4L ALERO, GRAND AM, IMPALA & MONTE CARLO article.
8. Disconnect the vacuum hose from the fuel pressure regulator. Monitor the fuel pressure gauge. Idle the engine. Apply 12-14 in. (34-47 kPa) of vacuum to the fuel pressure regulator using a Mityvac (J 23738-A), or equivalent. Does the fuel pressure drop 3-10 psi (21-69 kPa) when the vacuum is applied? If yes, go to step 21 . If no, go to step 23 .
9. Turn ignition switch to OFF position. Remove the vacuum hose from the fuel pressure regulator. Turn ignition switch to RUN position, engine OFF. Command the fuel pump ON using a scan tool. Check for a fuel leak from the fuel pressure regulator vacuum port. Is the fuel pressure regulator leaking fuel? If yes, go to step 23 . If no, go to next step.
10. Turn ignition switch to OFF position. Relieve the fuel pressure. See «FUEL PRESSURE RELIEF»(/chevrolet/monte-carlo/vi-1999-2007/remont/testing-diagnostics/#engine-controls-system-component-testing-34l__fuel-system-pressure-release) . Disconnect the fuel feed hose and the fuel return hose from the fuel rail pipes. Install the Fuel Line Shut-off Adapters (J 37287) between the fuel hoses and the fuel rail pipes. Open the valves on the fuel pipe shut-off adapters. Turn ignition switch to RUN position, engine OFF. Command the fuel pump ON using a scan tool. Bleed the air from the fuel pressure gauge. Command the fuel pump ON using a scan tool, to obtain the highest possible fuel pressure. Close the fuel feed pipe shut-off valve. Monitor the fuel pressure gauge for one minute. Does the fuel pressure remain constant? If yes, go to step 19 . If no, go to next step.
11. Turn ignition switch to OFF position. Open the fuel feed pipe shut-off valve. Turn ignition switch to RUN position, engine OFF. Command the fuel pump ON and then OFF using a scan tool. Close the fuel return pipe shut-off valve. Monitor the fuel pressure gauge for one minute. Does the fuel pressure remain constant? If yes, go to step 23 . If no, go to step 20 .
12. Is the fuel pressure above 59 psi (427 kPa)? If yes, go to step 14 . If no, go to next step.
13. Is the fuel pressure above 0 psi (0 kPa)? If yes, go to step 16 . If no, go to step 17 .
14. Turn ignition switch to OFF position. Relieve the fuel pressure. See «FUEL PRESSURE RELIEF»(/chevrolet/monte-carlo/vi-1999-2007/remont/testing-diagnostics/#engine-controls-system-component-testing-34l__fuel-system-pressure-release) . Disconnect the fuel return hose from the fuel rail return pipe. Attach a length of flexible fuel hose to the fuel rail outlet passage. Place the flexible fuel hose open end into an approved gasoline container. Turn ignition switch to RUN position, engine OFF. Monitor the fuel pressure gauge while the fuel pump is operating. Is the fuel pressure 52-59 psi (358-405 kPa)? If yes, go to step 22 . If no, go to next step.
15. Check the fuel rail return pipe and fuel rail outlet passage for a restriction. Did you find and correct the condition? If yes, go to step 25 . If no, go to step 23 .
16. Turn ignition switch to OFF position. Relieve the fuel pressure. See «FUEL PRESSURE RELIEF»(/chevrolet/monte-carlo/vi-1999-2007/remont/testing-diagnostics/#engine-controls-system-component-testing-34l__fuel-system-pressure-release) . Disconnect the fuel return hose from the fuel rail return pipe. Install the Fuel Line Shut-Off Adapters (J 37287), or equivalent, between the fuel return pipe and the fuel rail. Open the valve in the fuel pipe shut-off adapter. Turn ignition switch to RUN position, engine OFF. Bleed the air from the fuel system. Monitor the fuel pressure gauge. Do NOT allow the fuel pressure to exceed 75 psi (517 kPa). Excessive pressure may damage the fuel system. Slowly close the valve in the fuel return pipe shut-off adapter. Command the fuel pump ON using a scan tool. Does the fuel pressure rise above 52 psi (358 kPa)? If yes, go to step 23 . If no, go to next step.
17. Check the fuel filter and fuel feed pipe for a restriction. Did you find and correct the condition? If yes, go to step 25 . If no, go to next step.
18. Check the fuel pump harness connectors and ground circuits for poor connections. If yes, go to step 25 . If no, go to next step.
19. Remove the fuel sender assembly. Check the following items: The fuel pump flex hose for damage. The in tank fuel pump harness connectors for poor connections. The fuel strainer for a restriction. Contaminates in the fuel tank. Did you find and correct the condition? If yes, go to step 25 . If no, go to step 24 .
20. Turn ignition switch to OFF position. Raise the fuel rail, with the fuel lines connected. Turn ignition switch to RUN position, engine OFF. Command the fuel pump ON using a scan tool. Locate and replace the leaking fuel injector. After repair, go to step 25 .
21. Repair the vacuum source to the fuel pressure regulator. After repair, go to step 25 .
22. Locate and repair the restricted fuel return line. After repair, go to step 25 .
23. Replace the fuel pressure regulator. After repair, go to step 25 .
24. Replace the fuel pump. After repair, go to next step.
25. Operate the system to verify the repair. Did you correct the condition? If yes, system is okay at this time. If no, go to step 3 .

FUEL TANK LEAK TEST

Note. For circuit reference, see WIRING DIAGRAMS . For component locations, see COMPONENT LOCATIONS . For connector identification, see CONNECTOR IDENTIFICATION in SELF-DIAGNOSTICS - 3.4L ALERO, GRAND AM, IMPALA & MONTE CARLO article.

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 completes one test cycle. The Malfunction Indicator Light (MIL) will illuminate after the EVAP diagnostics completes two test cycles.

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

1. 1 - This procedure determines that no EVAP diagnostic DTC is present.
2. 3 - This test locates fuel leakage in the fuel lines.
3. 4 - This tests for fuel leaks below the fuel tank fuel level.
4. 5 - This test locates fuel vapors escaping above the fuel level in the fuel tank.

1. Perform diagnostic system check - engine controls. See «DIAGNOSTIC SYSTEM CHECK - ENGINE CONTROLS»(/chevrolet/monte-carlo/vi-1999-2007/remont/testing-diagnostics/#engine-controls-self-diagnostics-34l) in SELF-DIAGNOSTICS - 3.4L ALERO, GRAND AM, IMPALA & MONTE CARLO article. After performing diagnostic system check - engine controls, go to next step.
2. Raise and support the vehicle. Check the fuel tank and fuel pipes for damage or external leaks. Did you find fuel leaking from the fuel tank? If yes, go to step 7 . If no, go to next step.
3. Turn ignition switch to RUN position, engine OFF. Command the fuel pump ON using a scan tool. Check for fuel leaking from the fuel pipes. Did fuel leak from the fuel pipes? If yes, go to step 8 . If no, go to next step.
4. Install the Fuel Tank Cap Adaptor (J 41415-40). Connect the Evaporative Emissions System Tester (EEST) (J 41413-200) to the fuel tank cap adaptor. Seal the EVAP system using a scan tool. Do not exceed 15 in. H2O. Pressurize the fuel tank the EEST. Did fuel leak from the fuel tank? If yes, go to step 7 . If no, go to next step.
5. Maintain pressure in the fuel tank using the EEST. Using the Ultrasonic Leak Detector (J 41416), test for leaks above the fuel level in the following locations: The fuel tank, fill limiter vent valve, pressure relief valve and rollover valve. The fuel sender housing and fuel sender seal. The FTP sensor seal. The fuel fill pipe and hose. Did you locate a fuel leak? If yes, go to next step. If no, go to «DIAGNOSTIC AIDS»(/chevrolet/monte-carlo/vi-1999-2007/remont/testing-diagnostics/#engine-controls-system-component-testing-34l) .
6. Repair the system as necessary. Did you complete the repair? If yes, system is okay at this time.
7. Replace the fuel tank. Did you complete the repair? If yes, system is okay at this time.
8. Replace the leaking fuel pipe. Did you complete the repair? If yes, system is okay at this time.

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. Test for fuel leaking in the following locations: The fuel tank. The fuel feed and return pipes.
3. Test for fuel vapor leaks in the following locations: The fuel tank, fill limiter vent valve and rollover valves. The fuel fill pipe, hose and fuel fill cap. The fuel sender housing and seal. The Fuel Tank Pressure (FTP) sensor seal. The EVAP vapor pipe.
4. Movement of the EVAP pipes or fuel pipes may help find an intermittent condition.

IGNITION SYSTEMS

Note. For basic ignition system checks, see BASIC DIAGNOSTIC PROCEDURES - 3.4L ALERO, GRAND AM, IMPALA & MONTE CARLO article.

Note. For ignition system testing, perform related DTC testing procedure. See SELF-DIAGNOSTICS - 3.4L ALERO, GRAND AM, IMPALA & MONTE CARLO article.

ELECTRONIC IGNITION SYSTEM DIAGNOSIS

Note. For circuit reference, see WIRING DIAGRAMS . For component locations, see COMPONENT LOCATIONS . For connector identification, see CONNECTOR IDENTIFICATION in SELF-DIAGNOSTICS - 3.4L ALERO, GRAND AM, IMPALA & MONTE CARLO article.

The Ignition Control Module (ICM) has independent power and ground circuits. The circuits between the ICM and the Powertrain Control Module (PCM) consist of the following circuits

1. The IC timing signal.
2. The IC timing control.
3. The low-resolution engine speed signal.
4. A low reference signal.

The ICM sends 3X signals to the PCM. The ICM controls the timing advance during engine cranking. The timing advance changes to PCM control after the following actions

1. The PCM receives the second 3X signal.
2. The PCM applies 5-volts to the IC timing signal circuit.

1. Perform diagnostic system check - engine controls. See «DIAGNOSTIC SYSTEM CHECK - ENGINE CONTROLS»(/chevrolet/monte-carlo/vi-1999-2007/remont/testing-diagnostics/#engine-controls-self-diagnostics-34l) in SELF-DIAGNOSTICS - 3.4L ALERO, GRAND AM, IMPALA & MONTE CARLO article. After performing diagnostic system check - engine controls, go to next step.
2. Attempt to start the engine. Does the engine start and run? If yes, go to next step. If no, go to step 4 .
3. Disconnect the Crankshaft Position Sensor (CKP) sensor "B" connector from the Ignition Control Module (ICM). Measure the resistance from the CKP sensor "B" CKP sensor 1 signal circuit to the low reference circuit using a DMM. Is the resistance 800-1200 ohms? If yes, go to next step. If no, go to step 28 .
4. Disconnect the CKP "A". Observe the 3X crank sensor parameter using a scan tool. Crank the engine. Does the scan tool indicate a 3X crank sensor signal present? If yes, go to next step. If no, go to step 11 .
5. Reconnect the CKP sensor "A". Test for spark at each cylinder using a Spark Tester (J 26792), or equivalent. Did you observe any non-sparking cylinders? If yes, go to next step. If no, go to step 9 .
6. Check and test the affected cylinder spark plug wires, the ignition coils, and the spark plugs for a short to ground or an arching to ground. If carbon tracking or corrosion is present, replace both components that are affected. Did you find and correct the condition? If yes, go to step 32 . If no, go to next step.
7. Test the spark plug wire resistances. Is the resistance more than 3000 ohms per foot (9868 ohms per meter)? If yes, go to step 30 . If no, go to next step.
8. Measure the ignition coils secondary resistance. Is the resistance 5000-8000 ohms? If yes, go to step 25 . If no, go to step 29 .
9. Check the spark plug wires for proper routing and for the correct firing order. If any spark plug wires are found to be misrouted, reroute as necessary. Did you find and correct the condition? If yes, go to step 32 . If no, go to next step.
10. Remove the spark plugs. Inspect spark plugs. Did you find the problem? If yes, go to step 31 . If no, go to «DIAGNOSTIC AIDS»(/chevrolet/monte-carlo/vi-1999-2007/remont/testing-diagnostics/#engine-controls-system-component-testing-34l)
11. Connect the CKP sensor "A". Disconnect the ICM harness connector. Turn ignition switch to RUN position. Connect a test light between the ICM ignition 1 voltage circuit and a good ground. Does the test light illuminate? If yes, go to next step. If no, go to step 24 .
12. Connect a test light between the ICM ignition 1 voltage circuit and the ICM ground circuit. Does the test light illuminate? If yes, go to next step. If no, go to step 26 .
13. Test for an intermittent and for a poor connection at the ICM. Did you find and correct the condition? If yes, go to step 32 . If no, go to next step.
14. Disconnect the CKP sensor "B" connector from the ICM. Probe the CKP sensor "B" CKP sensor 1 signal circuit using a test light connected to battery voltage. Does the test light illuminate? If yes, go to step 17 . If no, go to next step.
15. Probe the CKP sensor "B" CKP sensor 1 signal circuit using a test light connected to a good ground. Does the test light illuminate? If yes, go to step 18 . If no, go to next step.
16. Turn ignition switch to OFF position. Measure the resistance between the CKP sensor 1 signal circuit and the CKP sensor "B" low reference circuit using the DMM at the ICM harness connector. Is the resistance 800-1200 ohms? If yes, go to step 27 . If no, go to step 19 .
17. Test the CKP sensor 1 signal circuit for a short to ground. Did you find and correct the condition? If yes, go to step 32 . If no, go to step 20 .
18. Test the CKP sensor 1 signal circuit for a short to voltage. Did you find and correct the condition? If yes, go to step 32 . If no, go to step 20 .
19. Test the CKP sensor "B" circuits for the following conditions: An open. The CKP sensor 1 signal and the low reference circuit shorted together. Test for an intermittent and for a poor connection at the ICM. Did you find and correct the condition? If yes, go to step 32 . If no, go to step 20 .
20. Test for an intermittent and for a poor connection at the ICM. Did you find and correct the condition? If yes, go to step 32 . If no, go to next step.
21. Test for an intermittent and for a poor connection at the CKP sensor. Did you find and correct the condition? If yes, go to step 32 . If no, go to next step.
22. Remove the CKP sensor. Visually inspect the CKP sensor for the following conditions: Physical Damage. Excessive play or looseness. Improper installation. Foreign material passing between the CKP sensor and the reluctor wheel. Wiring routed too closely to secondary ignition components. Did you find and correct the condition? If yes, go to step 32 . If no, go to next step.
23. Visually inspect the reluctor wheel for the following conditions: Foreign material passing between the CKP sensor and the reluctor wheel. Physical Damage. Excessive end play or looseness. Improper installation. Excessive air gap between the CKP sensor and the reluctor wheel. Did you find and correct the condition? If yes, go to step 32 . If no, go to step 28 .
24. Repair the open or the short to ground in the ICM ignition 1 voltage circuit. Replace the fuse if necessary. After repair, go to step 32 .
25. Remove the coils associated with the cylinder that did not have spark. Connect a test light across the ICM primary circuit, between the ICM terminals for the coils. Observe the test light while cranking the engine. Does the test light flash continuously while the engine is being cranked? If yes, go to step 29 . If no, go to step 27 .
26. Repair the open in the ICM ground circuit. After repair, go to step 32 .
27. Replace the ICM. After repair, go to step 32 .
28. Replace the CKP sensor "B". After repair, go to step 32 .
29. Replace the affected ignition coils. After repair, go to step 32 .
30. Replace the spark plug wires. After repair, go to step 32 .
31. Replace the spark plugs. After repair, go to next step.
32. Turn the ignition switch to OFF position for 30 seconds. Start the engine and operate the vehicle. Observe the MIL, vehicle performance, and driveability. Does the vehicle operate normally, with no MIL? If yes, system is okay at this time. If no, go to step 2 .

An arcing spark plug wire or an arcing ignition coil to the ICM may cause a stall, misfire or a no start condition. For an intermittent condition, go to INTERMITTENTS in SELF-DIAGNOSTICS - 3.4L ALERO, GRAND AM, IMPALA & MONTE CARLO article.

IGNITION RELAY DIAGNOSIS

Note. For circuit reference, see WIRING DIAGRAMS . For component locations, see COMPONENT LOCATIONS . For connector identification, see CONNECTOR IDENTIFICATION in SELF-DIAGNOSTICS - 3.4L ALERO, GRAND AM, IMPALA & MONTE CARLO article.

The ignition relay is a normally open relay. The relay armature is held in the open position by spring tension. When the ignition switch is turned to the run or start position, current will flow through the relay coil. A wire connected to the other end of the relay coil completes the path to ground. The electromagnetic field, created by the relay coil, overcomes the spring tension and moves the armature allowing the relay contacts to close. The closed relay contacts allow current to flow from the battery to the following fuses

1. Eng Devices
2. Oxy Sensors
3. DFI/MDL
4. Trans Sol
5. A/C Relay Fuse
6. Fuel Inj

When the ignition switch is turned to the OFF position, the electromagnetic field collapses. This action allows the spring tension to move the armature away from the relay contacts, which interrupts current flow to the fuses. If the ignition relay fails to close, the engine will crank, but will not run. The class 2 communications will be available with the use of a scan tool.

Note. The ignition relay table assumes that the vehicle battery is fully charged.

1. Perform diagnostic system check - engine controls. See «DIAGNOSTIC SYSTEM CHECK - ENGINE CONTROLS»(/chevrolet/monte-carlo/vi-1999-2007/remont/testing-diagnostics/#engine-controls-self-diagnostics-34l) in SELF-DIAGNOSTICS - 3.4L ALERO, GRAND AM, IMPALA & MONTE CARLO article. After performing diagnostic system check - engine controls, go to next step.
2. Turn ignition switch to RUN position, engine OFF. Remove the underhood bottom junction block cover. Probe the following fuses using a test light connected to a good ground: Eng Devices Oxy Sensors DFI/MDL Trans Sol A/C Relay Fuse Fuel Inj Does the test light illuminate on at least one test point of each fuse? If yes, go to next step. If no, go to step 11 .
3. Turn ignition switch to OFF position. Probe both test points of the FUEL INJ fuse using a test light connected to a good ground. Does the test light illuminate on either test point of the fuse? If yes, go to next step. If no, go to step 33 .
4. Turn ignition switch to OFF position. Remove the ignition relay from the underhood bottom junction block using Relay Puller Pliers (J 43244). Probe both test points of the ABS/PCM fuse (10-amp) using a test light connected to a good ground. Does the test light illuminate? If yes, go to step 7 . If no, go to next step.
5. Test the ignition relay load circuit between the ignition relay and the fuses to the circuit components for a short to battery positive voltage. Did you find and correct the condition? If yes, go to step 33 . If no, go to next step.
6. Turn ignition switch to OFF position. Remove the following fuses from the underhood bottom junction block: Eng Devices Oxy Sensor DFI/MDL Trans Sol A/C relay fuse Fuel Inj Probe all these fuse terminals in the underhood bottom junction block using a test light connected to a good ground. Does the test light illuminate at any of the fuse terminals? If yes, diagnose engine electrical system. Go to appropriate GENERATORS & REGULATORS article. If no, go to step 30 .
7. Turn ignition switch to OFF position. Disconnect the left Instrument Panel (I/P) junction block harness connector that contains the ignition 1 voltage circuit between the left I/P junction block and the ignition relay. Test the ignition 1 voltage circuit between the left I/P junction block harness connector and the ignition relay for a short to battery positive voltage. Did you find and correct the condition? If yes, go to step 33 . If no, go to next step.
8. Test the ignition 1 voltage buss bar in the left I/P junction block for a short to battery voltage. Did you find a condition? If yes, go to step 32 . If no, go to next step.
9. Turn ignition switch to OFF position. Disconnect the left I/P junction block harness connector that contains the ignition 1 voltage circuit between the ignition switch and the left I/P junction block. Test the ignition 1 voltage circuit between the ignition switch and the left I/P junction block harness connector for a short to battery voltage. Did you find and correct the condition? If yes, go to step 33 . If no, go to next step.
10. Turn ignition switch to OFF position. Probe the ignition 1 voltage circuit at the ignition switch harness connector using a test light connected to a good ground. Does the test light illuminate? If yes, go to step 31 . If no, go to step 30 .
11. Turn ignition switch to OFF position. Probe both test points of the underhood No. 2 MAXI fuse (60-amp) using a test light connected to a good ground. Does the test light illuminate on both test points of the fuse? If yes, go to step 14 . If no, go to next step.
12. Test the battery positive voltage circuit between the ignition relay and the underhood No. 2 MAXI fuse (60-amp) for a short to ground. Did you find and correct the condition? If yes, go to step 33 . If no, go to next step.
13. Test the relay load circuit between the ignition relay and the fuses to the circuit components for a short to ground. Did you find and correct the condition? If yes, go to step 33 . If no, go to step 30 .
14. Turn ignition switch to RUN position, engine OFF. Probe both test points of the ABS/PCM fuse (10-amp) in the left I/P junction block using a test light connected to a good ground. Does the test light illuminate on both test points of the fuse? If yes, go to step 20 . If no, go to next step.
15. Does the test light illuminate on one test point of the ABS/PCM fuse? If yes, go to next step. If no, go to step 17 .
16. Turn ignition switch to OFF position. Disconnect the left I/P junction block harness connector that contains the ignition 1 voltage circuit between the left I/P junction block and the ignition relay. Test the ignition 1 voltage circuit between the ignition relay and the left I/P junction block harness connector for a short to ground. Did you find and correct the condition? If yes, go to step 33 . If no, go to step 18 .
17. Turn ignition switch to OFF position. Disconnect the left I/P junction block harness connector that contains the ignition 1 voltage from the ignition switch. Turn ignition switch to RUN position, engine OFF. Probe the ignition 1 voltage circuit at the left I/P junction block harness connector using a test light connected to a good ground. Does the test light illuminate? If yes, go to step 32 . If no, go to step 19 .
18. Test the ignition 1 voltage buss bar in the left I/P junction block for a short to ground. Did you find a condition? If yes, go to step 32 . If no, go to step 30 .
19. Turn ignition switch to OFF position. Test the ignition 1 voltage circuit between the ignition switch and the left I/P junction block harness connector for an open. Did you find and correct the condition? If yes, go to step 33 . If no, go to step 31 .
20. Turn ignition switch to OFF position. Remove the ignition relay using the Puller (J 43244). Probe the ignition relay battery positive voltage circuit at the underhood bottom junction block using a test light connected to a good ground. Does the test light illuminate? If yes, go to next step. If no, go to step 26 .
21. Turn ignition switch to RUN position, engine OFF. Probe the ignition relay ignition 1 voltage circuit at the underhood bottom junction block using a test light connected to a good ground. Does the test light illuminate? If yes, go to next step. If no, go to step 25 .
22. Turn ignition switch to RUN position, engine OFF. Probe the ignition relay coil ground circuit at the underhood bottom junction block, using a test light connected to battery voltage. Does the test light illuminate? If yes, go to next step. If no, go to step 28 .
23. Turn ignition switch to OFF position. Connect a 20-amp fused jumper wire between the battery voltage circuit and the ignition relay load circuit at the underhood bottom junction block. Probe the following fuses using a test light connected to a good ground: Eng Devices Oxy Sensor DFI/MDL Trans Sol A/C relay fuse Fuel INJ Does the test light illuminate on at least one test point of each fuse? If yes, go to next step. If no, go to step 29 .
24. Test for an intermittent and poor connection at the underhood bottom junction block, ignition relay connector location. Did you find and correct a condition? If yes, go to step 33 . If no, go to step 30 .
25. Test the ignition 1 voltage buss bar circuit in the left I/P junction block between the ABS/PCM fuse (10-amp) and the ignition relay for an open. Did you find a condition? If yes, go to step 32 . If no, go to step 27 .
26. Repair the high resistance or an open in the battery voltage circuit to the ignition relay. After repair, go to 33 .
27. Repair the high resistance or an open in the ignition relay ignition 1 voltage circuit. After repair, go to 33 .
28. Repair the high resistance or an open in the ignition relay ground circuit. After repair, go to 33 .
29. Repair the high resistance or an open in the ignition relay load circuit. After repair, go to 33 .
30. Replace the ignition relay. After repair, go to 33 .
31. Replace the ignition switch. After repair, go to 33 .
32. Replace the left I/P junction block. After repair, go to next step.
33. Replace any open fuses. Turn ignition switch to OFF position for 30 seconds. Attempt to start the engine. Does the engine start and run? If yes, go to next step. If no, go to «NO-START DIAGNOSIS»(/chevrolet/monte-carlo/vi-1999-2007/remont/testing-diagnostics/#engine-controls-basic-diagnostic-procedures-34l__no-start-diagnosis) in BASIC DIAGNOSTIC PROCEDURES - 3.4L ALERO, GRAND AM, IMPALA & MONTE CARLO article.
34. Clear the DTCs using a scan tool. Operate the vehicle for 5 minutes. Do the DTCs set during this ignition cycle? If yes, go to «DIAGNOSTIC TROUBLE CODE DEFINITIONS»(/chevrolet/monte-carlo/vi-1999-2007/remont/testing-diagnostics/#engine-controls-self-diagnostics-34l__diagnostic-trouble-code-definitions) in SELF-DIAGNOSTICS - 3.4L ALERO, GRAND AM, IMPALA & MONTE CARLO article. If no, system is okay at this time.

EXHAUST GAS RECIRCULATION

A malfunction in Exhaust Gas Recirculation (EGR) system can set a DTC. For testing procedures and specifications, perform related DTC testing procedure. See DIAGNOSTIC TROUBLE CODE DEFINITIONS in SELF-DIAGNOSTICS - 3.4L ALERO, GRAND AM, IMPALA & MONTE CARLO article.

FUEL EVAPORATION

Note. Ensure all vacuum line and EVAP system components are not damaged or missing before proceeding with this test.

EVAP Control System Diagnosis

A malfunction in EVAP Control System can set a DTC. For testing procedures and specifications, perform related DTC testing procedure. See DIAGNOSTIC TROUBLE CODE DEFINITIONS in SELF-DIAGNOSTICS - 3.4L ALERO, GRAND AM, IMPALA & MONTE CARLO article.

Required Service

The PCV system may require service for obstructions if any of the following conditions exist

1. Rough idle.
2. Stalling or slow idle speed.
3. Oil leaks.
4. Oil in air cleaner.
5. Sludge in engine.

A leaking PCV valve or hose could cause

1. Rough idle.
2. Stalling.
3. High idle speed.

If engine idles rough, check for clogged PCV valve, or plugged or broken hoses BEFORE adjusting idle. Check PCV valve application to ensure correct valve is fitted. Replace PCV valve if required.

Checking PCV Valve Function

1. Disconnect PCV valve vacuum hose from cylinder head cover. Run engine at idle. Place thumb over open end of PCV valve vacuum hose to check for vacuum. If vacuum does not exist, check for obstruction in source vacuum supply. If source vacuum supply is okay, replace PCV valve.
2. Turn ignition switch to OFF position. Remove PCV valve. Shake valve and listen for rattle of check valve inside PCV valve. If a clear rattle is not heard, replace PCV valve.
3. Visually inspect valve for varnish or deposits which may make PCV valve operation sticky or restricted, or cause incomplete seating of valve. Replace as necessary.
4. Engine must be sealed for PCV system to function as designed. If leakage, sludging or dilution of oil is noted and PCV system is functioning properly, check engine for cause and repair as required to ensure PCV system will continue to function properly.
5. An engine operating without any crankcase ventilation can be damaged, so it is important to replace PCV valve and air cleaner breather (if equipped) at regular intervals (at least every 30,000 miles). Check all hoses and clamps for failure or deterioration.

EXHAUST LEAKAGE

Perform SYMPTOM DIAGNOSIS - ENGINE EXHAUST under SYMPTOMS in TROUBLE SHOOTING - 3.4L ALERO, GRAND AM, IMPALA & MONTE CARLO article prior to performing this diagnostic procedure.

Symptom Definition

An exhaust leak may show stains at the area of the leak. The leak may be felt by holding a hand close to the suspected areas or using a smoke pencil. The leak may make a popping or hissing noise.

Diagnosis

EXHAUST LEAKAGE DIAGNOSIS

EXHAUST NOISE

Perform SYMPTOM DIAGNOSIS - ENGINE EXHAUST under SYMPTOMS in TROUBLE SHOOTING - 3.4L ALERO, GRAND AM, IMPALA & MONTE CARLO article prior to performing this diagnostic procedure.

An audible or physical noise due to a faulty component or damaged components causing a loose or misaligned exhaust system resulting in a rattle or vibration noise, i.e. buzz, groan or hum.

EXHAUST NOISE DIAGNOSIS

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

1. 4 - The exhaust system has very low back pressure under normal conditions. If the exhaust system is restricted, a significant increase in the exhaust pressure is noticed on the Exhaust Back Pressure Gauge (J 35314-A). Removing the HO2S sensor may set a DTC. When finishing this diagnostic table, be sure to clear all codes. Removing the AIR check valve or Heated Oxygen Sensor (HO2S) may set a DTC. When finishing this diagnostic procedure, ensure to clear all codes.
2. 5 - This step will isolate the catalytic converter from the remainder of the exhaust system.
3. 8 - The symptom still exists and the vehicle has a dual exhaust system, proceed to Step 2 and repeat diagnostic procedure on the opposite exhaust pipe.

1. Did you verify the customers complaint? If yes, go to next step.
2. Did you review the exhaust symptoms diagnostic information and perform the necessary inspections? If yes, go to next step. If no, go to «SYMPTOM DIAGNOSIS - ENGINE EXHAUST»(/chevrolet/monte-carlo/vi-1999-2007/remont/testing-diagnostics/#engine-controls-trouble-shooting-no-codes-34l) under SYMPTOMS in TROUBLE SHOOTING - 3.4L ALERO, GRAND AM, IMPALA & MONTE CARLO article.
3. Is the system equipped with dual exhaust? If yes, go to «DIAGNOSTIC AIDS»(/chevrolet/monte-carlo/vi-1999-2007/remont/testing-diagnostics/#engine-controls-system-component-testing-34l) . If no, go to next step.
4. Remove the HO2S 2 located in front of and closest to the catalytic converter. Install the Exhaust Back Pressure Gauge (J 35314-A) in place of the AIR check valve or HO2S sensor. Start the engine. Observe the exhaust system back pressure reading on the gauge. Does the reading exceed 2 psi (14 kPa)? If yes, go to next step. If no, go to step 8 .
5. Turn ignition switch to LOCK position. Remove the exhaust back pressure gauge still installed increase and monitor engine speed to 2000 RPM. Re-install the AIR check valve/O2S. Remove the post-catalytst HO2S 2. Install the exhaust back pressure gauge in place of the HO2S 2. Start the engine. Increase and monitor the engine speed at 2000 RPM. Observe the exhaust system back pressure reading on the gauge. Does the reading exceed 2 psi (14 kPa)? If yes, go to next step. If no, go to step 7 .
6. Check the exhaust system for the following conditions: Damage in the exhaust pipe. Debris in the exhaust pipe. Muffler or resonator internal failure. Two-layer exhaust pipe separation. Repair as necessary. Did you find and correct the condition? If yes, go to step 8 .
7. Replace the catalytic converter. After repair, go to next step.
8. Remove the exhaust back pressure gauge and reinstall the AIR check valve or the HO2S. Using a scan tool, clear any codes. Road test the vehicle to verify the repair. Did you correct the condition? If yes, system is okay at this time. If no, go to step 2 .

For dual exhaust systems a quick check of exhaust flow will help determine which side of the exhaust system is restricted. The side that has less exhaust flow is the side that will be suspect, and the diagnosis should begin there.

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

1. 4 - The exhaust system has very low back pressure under normal conditions. If the exhaust system is restricted, a significant increase in the exhaust pressure is noticed on the Exhaust Back Pressure Gauge (J 35314-A). Removing the HO2S sensor may set a DTC. When finishing this diagnostic table, be sure to clear all codes.
2. 5 - This step will isolate the catalytic converter from the remainder of the exhaust system.
3. 8 - Confirming that the condition has been fixed is essential. If the symptom still exists and the vehicle has a dual exhaust system, proceed to step 2 and repeat the diagnostic procedure on the opposite exhaust pipe.

1. Did you verify the customers complaint? If yes, go to next step.
2. Did you review the exhaust symptoms diagnostic information and perform the necessary inspections? If yes, go to next step. If no, go to «SYMPTOM DIAGNOSIS - ENGINE EXHAUST»(/chevrolet/monte-carlo/vi-1999-2007/remont/testing-diagnostics/#engine-controls-trouble-shooting-no-codes-34l) under SYMPTOMS in TROUBLE SHOOTING - 3.4L ALERO, GRAND AM, IMPALA & MONTE CARLO article.
3. Is the system equipped with dual exhaust? If yes, go to «DIAGNOSTIC AIDS»(/chevrolet/monte-carlo/vi-1999-2007/remont/testing-diagnostics/#engine-controls-system-component-testing-34l) . If no, go to next step.
4. Remove the pre-catalyst Heated Oxygen Sensor 1 (HO2S 1). Install the Exhaust Back Pressure Gauge (J 35314-A) in place of the HO2S 1. Start and run the vehicle. Increase and monitor the engine speed at 2500 RPM. Observe the exhaust system back pressure reading on the gauge. Does the reading exceed 1.25 psi (9 kPa)? If yes, go to next step. If no, go to step 8 .
5. Turn the engine off and place the ignition switch in LOCK position. Remove the exhaust back pressure gauge. Install the pre-catalyst HO2S 1. Remove the post-catalyst HO2S 2. Install the exhaust back pressure gauge in place of the post HO2S 2. Start the engine. Increase and monitor the engine speed at 2500 RPM. Observe the exhaust system back pressure reading on the gauge. Does the reading exceed 1.25 psi (9 kPa)? If yes, go to next step. If no, go to step 7 .
6. Check the exhaust system for the following conditions: Damage in the exhaust pipe. Debris in the exhaust pipe. Muffler or resonator internal failure. Two-layer exhaust pipe separation. Did you find and correct the condition? If yes, go to step 8 .
7. Replace the catalytic converter. After repair, go to next step.
8. Remove the exhaust back pressure gauge. Install the post-catalyst HO2S 2. Clear any codes. Road test the vehicle to verify the repair. Did you correct the condition? If yes, system is okay at this time. If no, go to step 2 .

For dual exhaust systems a quick check of exhaust flow will help determine which side of the exhaust system is restricted. The side that has less exhaust flow is the side that will be suspect, and the diagnosis should begin there.

MISCELLANEOUS CONTROLS

Note. Although some of the controlled devices listed here are not technically engine performance components, they can affect driveability if they malfunction.

Note. Manufacturer does not provide testing procedures for many individual systems and components. For system and component testing not listed, perform related DTC testing procedure. See SELF-DIAGNOSTICS - 3.4L ALERO, GRAND AM, IMPALA & MONTE CARLO article.

A/C COMPRESSOR CLUTCH CONTROLS

Note. For A/C compressor clutch circuit testing, see appropriate MANUAL or AUTOMATIC A/C-HEATER SYSTEMS article in AIR CONDITIONING & HEATING.

ELECTRIC COOLING FAN

Note. For electric cooling fan circuit testing, see appropriate ELECTRIC COOLING FANS article in ENGINE COOLING.

TRANSMISSION

Note. For transmission electronic controls testing, see appropriate DIAGNOSIS article in AUTOMATIC TRANSMISSIONS.

ALERO

See ENGINE PERFORMANCE in SYSTEM WIRING DIAGRAMS article in ELECTRICAL.

GRAND AM

See ENGINE PERFORMANCE in SYSTEM WIRING DIAGRAMS article in ELECTRICAL.

IMPALA

See ENGINE PERFORMANCE in SYSTEM WIRING DIAGRAMS article in ELECTRICAL.

MONTE CARLO

See ENGINE PERFORMANCE in SYSTEM WIRING DIAGRAMS article in ELECTRICAL.

See also:
• BASIC DIAGNOSTIC PROCEDURES - 3.4L ALERO, GRAND AM, IMPALA & MONTE CARLO
• DIAGNOSTIC STARTING POINT- ENGINE CONTROLS
• COMPONENT LOCATIONS
• DIAGNOSTIC TROUBLE CODE DEFINITIONS
• INTERMITTENTS
• SYMPTOM DIAGNOSIS - ENGINE CONTROLS
• DTC P0201-P0206: INJECTOR CONTROL CIRCUIT
• NO-START DIAGNOSIS
• SYMPTOM DIAGNOSIS - ENGINE EXHAUST
• WIRING DIAGRAMS
• COMPONENT LOCATIONS
• FUEL PUMP ELECTRICAL CIRCUIT DIAGNOSIS
• DIAGNOSTIC AIDS
• IGNITION RELAY DIAGNOSIS
• FUEL SYSTEM CLEANING
• FUEL INJECTOR COIL TEST
• FUEL SYSTEM DIAGNOSIS
• FUEL INJECTOR CLEANING
• FUEL INJECTOR COIL TEST
• FUEL INJECTOR BALANCE TEST
• FUEL INJECTOR BALANCE TEST WITH TECH 2
• FUEL PRESSURE RELIEF
• EXHAUST LEAKAGE