Engine Controls - System & Component Testing - 3.8l Buick Park Avenue II рестайлинг

INTRODUCTION

Before testing separate components or systems, follow proper workflow. See DIAGNOSTIC SYSTEM CHECK - ENGINE CONTROLS under SELF-DIAGNOSTIC SYSTEM in SELF-DIAGNOSTICS - 3.8L BONNEVILLE, GRAND PRIX, IMPALA, LESABRE, MONTE CARLO, PARK AVENUE & REGAL article. If no Diagnostic Trouble Codes (DTC) are present and a no-start condition exists, proceed to BASIC DIAGNOSTIC PROCEDURES - 3.8L BONNEVILLE, GRAND PRIX, IMPALA, LE SABRE, MONTE CARLO, PARK AVENUE & REGAL article. If no DTCs are present and a driveability condition exists, proceed to TROUBLE SHOOTING - NO CODES - 3.8L BONNEVILLE, GRAND PRIX, IMPALA, LE SABRE, MONTE CARLO, PARK AVENUE & REGAL article for diagnosis by symptom (i.e., ROUGH IDLE, ENGINE STALLS, etc.).

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

COMPONENT LOCATIONS (BONNEVILLE)

COMPONENT LOCATIONS (BONNEVILLE)

COMPONENT LOCATIONS (GRAND PRIX)

COMPONENT LOCATIONS (GRAND PRIX)

COMPONENT LOCATIONS (LESABRE)

COMPONENT LOCATIONS (LESABRE)

COMPONENT LOCATIONS (IMPALA & MONTE CARLO)

COMPONENT LOCATIONS (IMPALA & MONTE CARLO)

COMPONENT LOCATIONS (PARK AVENUE)

COMPONENT LOCATIONS (PARK AVENUE)

COMPONENT LOCATIONS (REGAL)

COMPONENT LOCATIONS (REGAL)

AIR INDUCTION SYSTEMS

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 - 3.8L BONNEVILLE, GRAND PRIX, IMPALA, LESABRE, MONTE CARLO, PARK AVENUE & REGAL article.

Note. For location of components, see COMPONENT LOCATIONS .

Description

Supercharger boost pressure is regulated to prevent engine and drivetrain damage. When the engine is operating under high boost conditions, the Powertrain Control Module (PCM) limits boost pressure to 8 psi (55 kPa). The PCM disables boost under the following conditions

1. When Reverse gear is selected.
2. When the vehicle is decelerating.
3. When the engine coolant temperature is excessively high.
4. When drivetrain abuse is detected.

The PCM controls boost pressure by using the boost control solenoid. The boost control solenoid is a normally open valve. Under most conditions, the PCM commands the boost control solenoid to operate at a 100 percent duty cycle. This keeps the solenoid valve closed and allows only inlet vacuum to control the position of the bypass valve. At idle, engine vacuum is applied to the upper side of the bypass valve actuator, counteracting spring tension to hold the bypass open. As engine load is increased, engine vacuum is decreased, causing the spring in the bypass valve actuator to overcome the applied vacuum, closing the bypass valve and allowing the boost pressure to increase. When reduced boost pressure is desired, the PCM commands the boost control solenoid to operate at a zero percent duty cycle. This opens the solenoid valve and allows boost pressure to enter the bypass valve actuator at the lower side to counteract the spring tension, opening the bypass valve and recirculating excess boost pressure back into the supercharger inlet.

Diagnostic Procedures

1. Perform Diagnostic System Check - Engine Controls. See «DIAGNOSTIC SYSTEM CHECK - ENGINE CONTROLS»(/buick/park-avenue/ii-2002-2005/remont/testing-diagnostics/#engine-control-system-self-diagnostics-38l) under SELF-DIAGNOSTIC SYSTEM in SELF-DIAGNOSTICS - 3.8L BONNEVILLE, GRAND PRIX, IMPALA, LESABRE, MONTE CARLO, PARK AVENUE & REGAL article. After performing Diagnostic System Check - Engine Controls, go to next step.
2. Check the following items and repair any condition as necessary: Vacuum lines for cracking, restrictions, and loose fit. The bypass valve actuator for sticking, binding, or damage. The bypass valve for sticking, binding, or damage. The bypass valve linkage for binding or damage. The boost control solenoid for damage. Did you find and correct the condition? If yes, go to step 16 . If no, go to next step.
3. Disconnect the boost signal hose from the bypass valve actuator. Connect a vacuum gauge to the boost signal hose. Start and idle the engine in Park. Does the vacuum gauge read near zero in. Hg? If yes, go to next step. If no, go to step 10 .
4. Connect a scan tool and command the boost control solenoid to zero percent duty cycle. Observe the vacuum gauge. Does the vacuum gauge read more than 15 in. Hg? If yes, go to next step. If no, go to step 8 .
5. Turn ignition switch to OFF position. Reconnect the boost signal hose to the bypass valve actuator. Disconnect the inlet vacuum signal hose from the bypass valve actuator. Connect a vacuum gauge to the inlet vacuum signal hose. Start and idle the engine in Park. Does the vacuum gauge read more than 15 in. Hg? If yes, go to next step. If no, go to step 13 .
6. Turn ignition switch to OFF position. Connect a vacuum pump to the inlet vacuum signal port on the bypass valve actuator. Slowly apply vacuum to 15 in. Hg. Does the bypass valve actuator retract? If yes, go to next step. If no, go to step 11 .
7. Reconnect the inlet vacuum signal hose to the bypass valve actuator. Disconnect the boost signal hose from the bypass valve actuator. Connect a vacuum pump to the boost signal port on the bypass valve actuator. Start and idle the engine in Park. Slowly apply vacuum to 20 in. Hg. Does the bypass valve actuator extend? If yes, system is okay at this time. If no, go to step 11 .
8. Turn ignition switch to OFF position. Reconnect the boost signal hose to the bypass valve actuator. Disconnect the boost signal hose from the boost control solenoid. Connect a vacuum gauge to the boost signal port on the boost control solenoid. Start and idle the engine in Park. Command the boost control solenoid to zero percent duty cycle. Does the vacuum gauge read more than 15 in. Hg? If yes, go to step 15 . If no, go to next step.
9. Turn ignition switch to OFF position. Disconnect the boost source hose from the boost control solenoid. Connect a vacuum gauge to the boost source hose. Start and idle the engine in Park. Does the vacuum gauge read more than 15 in. Hg? If yes, go to next step. If no, go to step 14 .
10. Replace the boost control solenoid. After repair, go to step 16 .
11. Check the bypass valve and bypass valve actuator linkage for binding, sticking or damage. Repair any condition as necessary. Did you find and correct a condition? If yes, go to step 16 . If no, go to next step.
12. Replace the bypass valve actuator. After repair, go to step 16 .
13. Repair the inlet vacuum signal hose for a restriction or blockage. After repair, go to step 16 .
14. Repair the boost source hose for a restriction or blockage. After repairs, go to step 16 .
15. Repair the boost signal hose for a restriction or blockage. After repair, go to next step.
16. 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 within conditions to verify the repair. Did you verify the repair? If yes, go to next step. If no, go to step 2 .
17. Using a scan tool, observe the stored information in CAPTURE INFO. 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»(/buick/park-avenue/ii-2002-2005/remont/testing-diagnostics/#engine-control-system-self-diagnostics-38l__diagnostic-trouble-code-definitions) in SELF-DIAGNOSTICS - 3.8L BONNEVILLE, GRAND PRIX, IMPALA, LESABRE, MONTE CARLO, PARK AVENUE & REGAL article. If no, system is okay at this time.

COMPUTERIZED ENGINE CONTROLS

Note. For location of components, see COMPONENT LOCATIONS .

POWERTRAIN CONTROL MODULE

Note. To identify circuits, see WIRING DIAGRAMS .

Ground Circuits

1. Using DVOM, check for continuity to ground at PCM ground terminals. For connector terminal identification, see «CONNECTOR IDENTIFICATION»(/buick/park-avenue/ii-2002-2005/remont/testing-diagnostics/#engine-control-system-self-diagnostics-38l) in SELF-DIAGNOSTICS - 3.8L BONNEVILLE, GRAND PRIX, IMPALA, LESABRE, MONTE CARLO, PARK AVENUE & REGAL article. See «WIRING DIAGRAMS»(/buick/park-avenue/ii-2002-2005/remont/testing-diagnostics/#engine-controls-system-component-testing-38l) . 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»(/buick/park-avenue/ii-2002-2005/remont/testing-diagnostics/#engine-control-system-self-diagnostics-38l) in SELF-DIAGNOSTICS - 3.8L BONNEVILLE, GRAND PRIX, IMPALA, LESABRE, MONTE CARLO, PARK AVENUE & REGAL article. See «WIRING DIAGRAMS»(/buick/park-avenue/ii-2002-2005/remont/testing-diagnostics/#engine-controls-system-component-testing-38l) . 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 appropriate battery feed 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 transmission/transaxle, depress clutch pedal. On vehicles with automatic transaxle, place gearshift lever in Park. On all vehicles, 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 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 - 3.8L BONNEVILLE, GRAND PRIX, IMPALA, LESABRE, MONTE CARLO, PARK AVENUE & REGAL 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 prior to testing, and after completing any repairs. See DIAGNOSTIC SYSTEM CHECK - ENGINE CONTROLS in SELF-DIAGNOSTICS - 3.8L BONNEVILLE, GRAND PRIX, IMPALA, LESABRE, MONTE CARLO, PARK AVENUE & REGAL 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 DIAGNOSTIC TROUBLE CODE DEFINITIONS in SELF-DIAGNOSTICS - 3.8L BONNEVILLE, GRAND PRIX, IMPALA, LESABRE, MONTE CARLO, PARK AVENUE & REGAL article.

Note. For location of components, see COMPONENT LOCATIONS .

A/C COMPRESSOR CLUTCH RELAY

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

CAMSHAFT POSITION SENSOR

Manufacturer does not provide testing procedures for many individual systems and components. A malfunction in Camshaft Position (CMP) sensor circuit can set a DTC. For testing procedures and specifications, perform related DTC testing procedure. See SELF-DIAGNOSTICS - 3.8L BONNEVILLE, GRAND PRIX, IMPALA, LESABRE, MONTE CARLO, PARK AVENUE & REGAL article.

CRANKSHAFT POSITION SENSOR

Manufacturer does not provide testing procedures for many individual systems and components. A malfunction in Crankshaft Position (CKP) sensor circuit can set a DTC. For testing procedures and specifications, perform related DTC testing procedure. See SELF-DIAGNOSTICS - 3.8L BONNEVILLE, GRAND PRIX, IMPALA, LESABRE, MONTE CARLO, PARK AVENUE & REGAL article.

ENGINE COOLANT TEMPERATURE SENSOR

1. Manufacturer does not provide testing procedures for many individual systems and components. A malfunction in Engine Coolant Temperature (ECT) sensor circuit can set a DTC. For testing procedures and specifications, perform related DTC testing procedure. See «SELF-DIAGNOSTICS - 3.8L BONNEVILLE, GRAND PRIX, IMPALA, LESABRE, MONTE CARLO, PARK AVENUE & REGAL»(/buick/park-avenue/ii-2002-2005/remont/testing-diagnostics/#engine-control-system-self-diagnostics-38l) article. An out-of-calibration ECT sensor may not set a DTC. Use the following procedure to test sensor calibration.
2. Disconnect ECT sensor harness connector. Using DVOM, measure resistance of ECT sensor at specified temperatures. See «TEMPERATURE VS. RESISTANCE»(/buick/park-avenue/ii-2002-2005/remont/testing-diagnostics/#engine-controls-system-component-testing-38l) table. Resistance should be high when engine is cold and drop as engine warms. With vehicle sitting overnight, IAT sensor and ECT sensor should have close to the same resistance reading. If resistance is not within specification, replace ECT sensor.

TEMPERATURE VS. RESISTANCE

FUEL LEVEL SENSOR

Manufacturer does not provide testing procedures for many individual systems and components. The PCM monitors the fuel level input for various diagnostics. A malfunction in fuel level sensor circuit can set a DTC. For testing procedures and specifications, perform related DTC testing procedure. See SELF-DIAGNOSTICS - 3.8L BONNEVILLE, GRAND PRIX, IMPALA, LESABRE, MONTE CARLO, PARK AVENUE & REGAL article.

FUEL TANK PRESSURE SENSOR

Manufacturer does not provide testing procedures for many individual systems and components. The PCM monitors the fuel level input for various diagnostics. A malfunction in Fuel Tank Pressure (FTP) sensor circuit can set a DTC. For testing procedures and specifications, perform related DTC testing procedure. See SELF-DIAGNOSTICS - 3.8L BONNEVILLE, GRAND PRIX, IMPALA, LESABRE, MONTE CARLO, PARK AVENUE & REGAL article.

HEATED OXYGEN SENSOR

Manufacturer does not provide testing procedures for many individual systems and components. A malfunction in Heated Oxygen (HO2S) sensor circuit can set a DTC. For testing procedures and specifications, perform related DTC testing procedure in SELF-DIAGNOSTICS - 3.8L BONNEVILLE, GRAND PRIX, IMPALA, LESABRE, MONTE CARLO, PARK AVENUE & REGAL article.

INTAKE AIR TEMPERATURE SENSOR

1. Manufacturer does not provide testing procedures for many individual systems and components. A malfunction in Intake Air Temperature (IAT) sensor circuit can set a DTC. For testing procedures and specifications, perform related DTC testing procedure. See «SELF-DIAGNOSTICS - 3.8L BONNEVILLE, GRAND PRIX, IMPALA, LESABRE, MONTE CARLO, PARK AVENUE & REGAL»(/buick/park-avenue/ii-2002-2005/remont/testing-diagnostics/#engine-control-system-self-diagnostics-38l) article. An out-of-calibration IAT sensor may not set a DTC. Use the following procedure to test sensor calibration.
2. Disconnect IAT sensor harness connector. Using DVOM, measure resistance of IAT sensor at specified temperatures. See «TEMPERATURE VS. RESISTANCE»(/buick/park-avenue/ii-2002-2005/remont/testing-diagnostics/#engine-controls-system-component-testing-38l) table. Resistance should be high when air temperature is cold and drop as air temperature warms. With vehicle sitting overnight, ECT sensor and IAT sensor should have close to the same resistance reading. If resistance is not within specification, replace IAT sensor.

KNOCK SENSOR

Manufacturer does not provide testing procedures for many individual systems and components. A malfunction in Knock Sensor (KS) circuit can set a DTC. For testing procedures and specifications, perform related DTC testing procedure. See SELF-DIAGNOSTICS - 3.8L BONNEVILLE, GRAND PRIX, IMPALA, LESABRE, MONTE CARLO, PARK AVENUE & REGAL article.

The Manifold Absolute Pressure (MAP) sensor responds to changes in intake manifold pressure which gives an indication of the engine load. The MAP sensor has a 5-volt reference circuit, a low reference circuit, and a signal circuit. The Powertrain Control Module (PCM) supplies 5 volts to the MAP sensor on the 5-volt reference circuit and provides a ground on the low reference circuit. The MAP sensor provides a signal to the PCM on the MAP sensor signal circuit, which is relative to the pressure changes in the manifold. With low MAP, such as during idle or deceleration, the PCM should detect a low MAP sensor signal voltage. With high MAP, such as ignition ON, engine OFF or Wide Open Throttle (WOT), the PCM should detect a high MAP sensor signal voltage. This MAP sensor will indicate pressure between 1.4 and 15.8 psi (10 and 104 kPa) on models not equipped with a supercharger (VIN K) and between 1.16 and 30.16 (8 and 208 kPa) on models equipped with a supercharger (VIN 1). The MAP sensor is also used to calculate the Barometric Pressure (BARO) when the ignition switch is turned to RUN position, with the engine OFF. The BARO reading may also be updated whenever the engine is operated at WOT. The PCM monitors the MAP sensor signal for voltage outside of the normal range. If the PCM detects a MAP sensor signal voltage that is excessively low, DTC P0107 sets. If the PCM detects a MAP sensor signal voltage that is excessively high, DTC P0108 sets.

Test Description

The number below refers to the step number in the diagnostic procedure.

1. 4 - This step tests the MAP sensor's ability to correctly indicate BARO.

Diagnostic Procedure

1. Perform Diagnostic System Check - Engine Controls. See «DIAGNOSTIC SYSTEM CHECK - ENGINE CONTROLS»(/buick/park-avenue/ii-2002-2005/remont/testing-diagnostics/#engine-control-system-self-diagnostics-38l) under SELF-DIAGNOSTIC SYSTEM in SELF-DIAGNOSTICS - 3.8L BONNEVILLE, GRAND PRIX, IMPALA, LESABRE, MONTE CARLO, PARK AVENUE & REGAL article. After performing Diagnostic System Check - Engine Controls, go to next step.
2. Check for the following conditions: Vacuum hoses disconnected, damaged, or incorrectly routed. MAP sensor seal missing or damaged. Restrictions in the MAP sensor vacuum source. Intake manifold vacuum leaks. Did you find and correct the condition? If yes, go to step 24 . If no, go to next step.
3. Do you have access to another vehicle in which the MAP sensor pressure can be observed using a scan tool? If yes, go to next step. If no, go to step 5 .
4. Turn ignition switch to RUN position, engine OFF. Observe the MAP sensor pressure using a scan tool. Observe the MAP sensor pressure in the known good vehicle using a scan tool. Compare the values. Is the difference between the values less than 3 kPa? If yes, go to step 6 . If no, go to step 10 .
5. Turn ignition switch to RUN position, engine OFF. Observe the MAP sensor pressure using a scan tool. See «ALTITUDE VS. BAROMETRIC PRESSURE»(/buick/park-avenue/ii-2002-2005/remont/testing-diagnostics/#engine-controls-system-component-testing-38l) table. The MAP sensor pressure should be within the range specified for your altitude. Does the MAP sensor indicate the correct barometric pressure? If yes, go to next step. If no, go to step 10 .
6. Observe the MAP sensor pressure using a scan tool. Start the engine. Does the MAP sensor pressure change? If yes, go to next step. If no, go to step 10 .
7. Turn ignition switch to OFF position. Remove the MAP sensor from the engine vacuum source. Leave the MAP sensor connected to the engine harness. Connect a hand vacuum pump to the MAP sensor. Turn ignition switch to RUN position, engine OFF. Observe the MAP sensor pressure using the scan tool. Apply vacuum to the MAP sensor using the hand vacuum pump in one in. Hg increments until 15 in Hg is reached. Each one in. Hg should decrease MAP sensor pressure by 3-4 kPa. Is the decrease in MAP sensor pressure consistent? If yes, go to next step. If no, go to step 10 .
8. Apply vacuum using the hand vacuum pump until 20 in Hg is reached. Is the MAP sensor pressure less than 34 kPa? If yes, go to next step. If no, go to step 10 .
9. Disconnect the hand vacuum pump from the MAP sensor. Does the MAP sensor pressure return to the value observed in step 4 or 5 ? If yes, system is okay at this time. If no, go to step 12 .
10. Disconnect the MAP sensor harness connector. Observe the MAP sensor parameter using the scan tool. Is the voltage less than 0.1 volt? If yes, go to next step. If no, go to step 15 .
11. Measure the voltage from the 5-volt reference circuit of the MAP sensor to a good ground using a DVOM. Is the voltage more than 5.2 volts? If yes, go to step 16 . If no, go to next step.
12. Probe the 5-volt reference circuit of the MAP sensor using a test light connected to a good ground. Is the test light OFF? If yes, go to step 17 . If no, go to next step.
13. Connect a 3-amp fused jumper wire between the MAP sensor 5-volt reference circuit and the MAP sensor signal circuit. Observe the MAP sensor parameter using the scan tool. Is the voltage more than 4.9 volts? If yes, go to next step. If no, go to step 18 .
14. Turn ignition switch to OFF position. Remove the jumper wire. Connect a jumper wire between each of the terminals in the MAP sensor harness connector and the corresponding terminal at the MAP sensor. Turn ignition switch to RUN position, engine OFF. Measure the voltage from the MAP sensor low reference circuit at the jumper wire terminal to a good ground using a DVOM. Is the voltage more than 0.2 volt? If yes, go to step 19 . If no, go to step 20 .
15. Check the MAP sensor signal circuit between the PCM and the MAP sensor for a short to voltage. Did you find and correct the condition? If yes, go to step 17 . If no, go to next step.
16. Check all of the branches of the 5-volt reference circuit that are shared with the MAP sensor for a short to voltage. Did you find and correct the condition? If yes, go to step 24 . If no, go to step 23 .
17. Check the 5-volt reference circuit between the PCM and the MAP sensor for an open or for high resistance. Did you find and correct the condition? If yes, go to step 24 . If no, go to step 21 .
18. Check the MAP sensor signal circuit between the PCM and the MAP sensor for a short to ground, an open or high resistance. Did you find and correct the condition? If yes, go to step 24 . If no, go to step 21 .
19. Check the low reference circuit between the PCM and the MAP sensor for high resistance or an open. Did you find and correct the condition? If yes, go to step 24 . If no, go to step 21 .
20. Check for an intermittent and for a poor connection at the MAP sensor. Did you find and correct the condition? If yes, go to step 24 . If no, go to step 22
21. Check for an intermittent and for a poor connection at the PCM. Did you find and correct the condition? If yes, go to step 24 . If no, go to step 23 .
22. Replace the MAP sensor. After repair, go to step 24 .
23. Replace PCM. Program replacement PCM. See «POWERTRAIN CONTROL MODULE»(/buick/park-avenue/ii-2002-2005/remont/testing-diagnostics/#engine-control-system-self-diagnostics-38l) under PROGRAMMING in SELF-DIAGNOSTICS - 3.8L BONNEVILLE, GRAND PRIX, IMPALA, LESABRE, MONTE CARLO, PARK AVENUE & REGAL article. After repair, go to next step.
24. Use the scan tool to clear the DTCs that may have set. Turn ignition switch to OFF position for 30 seconds. Start the engine. Did you correct the condition? If yes, system is okay at this time. If no, go to step 2 .

ALTITUDE VS. BAROMETRIC PRESSURE (1)

MASS AIRFLOW SENSOR

Manufacturer does not provide testing procedures for many individual systems and components. A malfunction in Mass Air Flow (MAF) sensor circuit can set a DTC. For testing procedures and specifications, perform related DTC testing procedure. See SELF-DIAGNOSTICS - 3.8L BONNEVILLE, GRAND PRIX, IMPALA, LESABRE, MONTE CARLO, PARK AVENUE & REGAL article.

THROTTLE POSITION SENSOR

Manufacturer does not provide testing procedures for many individual systems and components. A malfunction in Throttle Position (TP) sensor circuit can set a DTC. For testing procedures and specifications, perform related DTC testing procedure. See SELF-DIAGNOSTICS - 3.8L BONNEVILLE, GRAND PRIX, IMPALA, LESABRE, MONTE CARLO, PARK AVENUE & REGAL article.

TRANSMISSION INTERNAL MODE SWITCH

Manufacturer does not provide testing procedures for many individual systems and components. A malfunction in Transmission Internal Mode Switch circuit can set a DTC. For testing procedures and specifications, perform related DTC testing procedure. See appropriate DIAGNOSIS article in AUTOMATIC TRANSMISSIONS.

VEHICLE SPEED SENSOR

Manufacturer does not provide testing procedures for many individual systems and components. A malfunction in Vehicle Speed Sensor (VSS) sensor circuit can set a DTC. For testing procedures and specifications, perform related DTC testing procedure. See SELF-DIAGNOSTICS - 3.8L BONNEVILLE, GRAND PRIX, IMPALA, LESABRE, MONTE CARLO, PARK AVENUE & REGAL article.

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 - 3.8L BONNEVILLE, GRAND PRIX, IMPALA, LESABRE, MONTE CARLO, PARK AVENUE & REGAL article.

Note. For location of components, see COMPONENT LOCATIONS .

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

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 in BASIC DIAGNOSTIC PROCEDURES - 3.8L BONNEVILLE, GRAND PRIX, IMPALA, LESABRE, MONTE CARLO, PARK AVENUE & REGAL article.

IDLE AIR CONTROL VALVE

See IDLE CONTROL SYSTEMS .

IGNITION RELAY (BONNEVILLE, GRAND PRIX, IMPALA & MONTE CARLO)

Note. Manufacturer does not provide testing procedures for many individual systems and components. For ignition system diagnosis for LeSabre and Park Avenue, see ELECTRONIC IGNITION SYSTEM DIAGNOSIS under IGNITION SYSTEM in BASIC DIAGNOSTIC PROCEDURES 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 contact 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 diagnostic procedure assumes that the vehicle battery is fully charged.

1. Perform Diagnostic System Check - Engine Controls. See «DIAGNOSTIC SYSTEM CHECK - ENGINE CONTROLS»(/buick/park-avenue/ii-2002-2005/remont/testing-diagnostics/#engine-control-system-self-diagnostics-38l) under SELF-DIAGNOSTIC SYSTEM in SELF-DIAGNOSTICS - 3.8L BONNEVILLE, GRAND PRIX, IMPALA, LESABRE, MONTE CARLO, PARK AVENUE & REGAL 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 the 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. Remove the ignition relay from the underhood bottom junction block using Relay Puller Pliers (J 43244), or equivalent. Probe both test points of the ABS/PCM fuse 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. Check 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. Remove the following fuses from the underhood bottom junction block: Eng Devices Oxy Sen 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 circuit problem. See ENGINE ELECTRICAL DIAGNOSTIC SYSTEM CHECK under SELF-DIAGNOSTIC SYSTEM in appropriate GENERATORS & REGULATORS article. If no, go to step 30 .
7. Disconnect the left Instrument Panel (IP) junction block harness connector that contains the ignition 1 voltage circuit between the left IP junction block and the ignition relay. Check the ignition 1 voltage circuit between the left I/P junction block harness connector and the ignition relay 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.
8. Check the ignition 1 voltage Buss Bar in the left IP 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. Disconnect the left IP junction block harness connector that contains the ignition 1 voltage circuit between the ignition switch and the left IP junction block. Check the ignition 1 voltage circuit between the ignition switch and the left IP 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. 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. Check 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. Check 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 point of the ABS/PCM fuse in the left IP 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 IP junction block harness connector that contains the ignition 1 voltage circuit between the left IP junction block and the ignition relay. Check the ignition 1 voltage circuit between the ignition relay and the left IP 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 IP junction block harness connector that contains the ignition 1 voltage circuit from the ignition switch. Turn ignition switch to RUN position, engine OFF. Probe the ignition 1 voltage circuit at the left IP 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. Check the ignition 1 voltage Buss Bar in the left IP 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. Check the ignition 1 voltage circuit between the ignition switch and the left IP junction block harness connector for an open. Did you find and correct the condition? If yes, go to step 32 . If no, go to step 31 .
20. Turn ignition switch to OFF position. Remove the ignition relay using the relay puller pliers. Probe the battery positive voltage circuit of the ignition relay at the underhood bottom junction block using a test light connected to 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 1 voltage circuit of the ignition relay 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. Probe the ignition relay coil ground circuit at the underhood bottom junction block using a test light connected to a battery voltage. Does the test light illuminate? If yes, go to next step. If no, go to step 28 .
23. Turn ignition switch to RUN position. Connect a 20-amp fused jumper wire between the battery positive voltage circuit and the ignition relay load circuit at the underhood bottom junction block. Probe the following fuses with at 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. Check for an intermittent and for a poor connection at the underhood bottom junction block, ignition relay connector location. Did you find and correct the condition? If yes, go to step 33 . If no, go to step 30 .
25. Check the ignition 1 voltage Buss Bar circuit in the left IP junction block between the ABS/PCM fuse 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 the open in the battery voltage circuit to the ignition relay. After repair, go to step 33 .
27. Repair the high resistance or the open in the ignition 1 voltage circuit of the ignition relay. After repair, go to step 33 .
28. Repair the high resistance or the open in the ignition relay ground circuit. After repair, go to step 33 .
29. Repair the high resistance or the open in the load circuit of the ignition relay. After repair, go to step 33 .
30. Replace the ignition relay. After repair, go to step 33 .
31. Replace the ignition switch. After repair, go to step 33 .
32. Replace the left instrument panel junction block. After repair, go to step 33 .
33. Replace any open fuses. Turn ignition switch to OFF position for 30 seconds. Did you complete the replacement? If yes, go to next step. If no, go to «ENGINE CRANKS BUT DOES NOT RUN»(/buick/park-avenue/ii-2002-2005/remont/testing-diagnostics/#engine-controls-basic-diagnostic-procedures-38l__engine-cranks-but-does-not-run) under NO-START DIAGNOSTICS in BASIC DIAGNOSTIC PROCEDURES article.
34. Clear the DTCs using a scan tool. Operate the vehicle for 5 minutes. Does a DTC set during this ignition cycle? If yes, go to «DIAGNOSTIC TROUBLE CODE DEFINITIONS»(/buick/park-avenue/ii-2002-2005/remont/testing-diagnostics/#engine-control-system-self-diagnostics-38l__diagnostic-trouble-code-definitions) in SELF-DIAGNOSTICS - 3.8L BONNEVILLE, GRAND PRIX, IMPALA, LESABRE, MONTE CARLO, PARK AVENUE & REGAL article. If no, system is okay at this time.

IGNITION RELAY (REGAL)

Note. Manufacturer does not provide testing procedures for many individual systems and components. For ignition system diagnosis for LeSabre and Park Avenue, see ELECTRONIC IGNITION SYSTEM DIAGNOSIS under IGNITION SYSTEM in BASIC DIAGNOSTIC PROCEDURES 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 contact to close. The closed relay contacts allow current to flow from the battery to the following fuses

1. OXY SEN
2. ELEK IGN
3. F/INJR
4. TRANS
5. ENG EMIS

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 diagnostic procedure assumes that the vehicle battery is fully charged.

1. Perform Diagnostic System Check - Engine Controls. See «DIAGNOSTIC SYSTEM CHECK - ENGINE CONTROLS»(/buick/park-avenue/ii-2002-2005/remont/testing-diagnostics/#engine-control-system-self-diagnostics-38l) under SELF-DIAGNOSTIC SYSTEM in SELF-DIAGNOSTICS - 3.8L BONNEVILLE, GRAND PRIX, IMPALA, LESABRE, MONTE CARLO, PARK AVENUE & REGAL article. After performing Diagnostic System Check - Engine Controls, go to next step.
2. Turn ignition switch to RUN position, engine OFF. Remove the underhood junction block cover. Probe the following fuses using the test light connected to a good ground: OXY SEN ELEK IGN F/INJ TRANS ENG EMIS 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 ENG EMIS 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 36 .
4. Turn ignition switch to OFF position. Remove the ignition relay from the underhood junction block using Relay Puller Pliers (J 43244). Probe both test points of the PCM, BCM, U/H relay fuse in the Instrument Panel (IP) fuse block using a test light connected to a good ground. Does the test light illuminate on any of the fuse test points? If yes, go to step 8 . If no, go to next step.
5. Check the ignition relay load circuit bus bar of the underhood junction block between the ignition relay and the fuses to the circuit components for a short to battery positive voltage. Did you find a condition? If yes, go to step 35 . If no, go to next step.
6. Turn ignition switch to OFF position. Remove the following fuses from the underhood junction block: OXY SEN ELEK IGN F/INJR TRANS ENG EMIS Probe all these fuse terminals in the underhood junction block using a test light that is connected to a good ground. Does the test light illuminate at any of the fuse terminals? If yes, go to next step. If no, go to step 34 .
7. Turn ignition switch to OFF position. Remove the A/C clutch relay from the underhood junction block using the relay puller pliers. Probe both fuse terminals of the ENG EMIS fuse in the underhood junction block using a test light connected to a good ground. Does the test light illuminate on either fuse terminal? If yes, diagnose engine electrical circuit problem. See ENGINE ELECTRICAL DIAGNOSTIC SYSTEM CHECK under SELF-DIAGNOSTIC SYSTEM in appropriate GENERATORS & REGULATORS article. If no, go to step 34 .
8. Turn ignition switch to OFF position. Disconnect the ignition switch harness connector. Connect a 20-amp fused jumper wire from the battery positive voltage circuit terminal at the ignition switch connector, to the corresponding terminal at the vehicle harness connector. 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 33 . If no, go to next step.
9. Remove the following fuses from the I/P fuse block: TURN SIGNALS, CORN LPS AIR BAG CLUSTER PCM, BCM, U/H RELAY Probe the ignition switch harness connector ignition 1 voltage circuit that leads to the IP fuse block, using a test light connected to a good ground. Does the test light illuminate? If yes, go to step 30 . If no, go to next step.
10. Turn ignition switch to OFF position. Disconnect the harness connector at the underhood junction block that contains the ignition 1 voltage circuit of the ignition relay. Probe the ignition relay ignition 1 voltage circuit at the underhood junction block vehicle harness electrical 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 35 .
11. Turn ignition switch to OFF position. Probe both test points of the IGN 1 fuse (30-amp) in the underhood 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 15 . If no, go to next step.
12. Does the test light illuminate on one test point of the IGN 1 (30-amp) fuse? If yes, go to next step. If no, go to step 21 .
13. Check the battery positive voltage circuit between the underhood junction block and the ignition switch for a short to ground. Did you find and correct the condition? If yes, go to step 36 . If no, go to next step.
14. Check the ignition 1 voltage circuit between the ignition switch and the PCM/ECM, BCM, U/H relay fuse terminals in the IP fuse block for a short to ground. Did you find and correct the condition? If yes, go to step 36 . If no, go to step 33 .
15. Turn ignition switch to RUN position, engine OFF. Probe both test points of the PCM/ECM, BCM, U/H relay fuse 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 22 . If no, go to next step.
16. Does the test light illuminate on one test point of the PCM, BCM, U/H relay fuse? If yes, go to step 19 . If no, go to next step.
17. Check the ignition 1 voltage circuit between the ignition switch and the PCM, BCM, U/H relay fuse for a high resistance or for an open. Did you find and correct the condition? If yes, go to step 36 . If no, go to next step.
18. Check the battery positive voltage circuit between the underhood junction block and the ignition switch for a high resistance or for an open. Did you find and correct the condition? If yes, go to step 36 . If no, go to step 33 .
19. Check the ignition 1 voltage circuit between the IP fuse block and the underhood junction block for a short to ground. Did you find and correct the condition? If yes, go to step 36 . If no, go to next step.
20. Check the underhood junction block, ignition 1 voltage bus bar circuit to the ignition relay for a short to ground. Did you find and correct the condition? If yes, go to step 35 . If no, go to step 32 .
21. Turn ignition switch to OFF position. Probe the mounting stud for the battery positive cable at the underhood junction block using a test light connected to a good ground. Does the test light illuminate? If yes, go to step 35 . If no, diagnose engine electrical circuit problem. See ENGINE ELECTRICAL DIAGNOSTIC SYSTEM CHECK under SELF-DIAGNOSTIC SYSTEM in appropriate GENERATORS & REGULATORS article.
22. Turn ignition switch to OFF position. Remove the ignition relay using the relay puller pliers, from the underhood junction block. Probe the ignition relay battery positive voltage circuit at the underhood 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 35 .
23. Turn ignition switch to RUN position, engine OFF. Probe the ignition relay ignition 1 voltage circuit at the underhood junction block using a test light connected to a good ground. Does the test light illuminate? If yes, go to step 25 . If no, go to next step.
24. Check the ignition 1 voltage circuit between the I/P fuse block and the underhood junction block for a high resistance or for an open. Did you find and correct the condition? If yes, go to step 36 . If no, go to step 35 .
25. Turn ignition switch to RUN position, engine OFF. Probe the ignition relay coil ground circuit at the underhood junction block using a test light connected to battery voltage. Does the test light illuminate? If yes, go to step 27 . If no, go to next step.
26. Turn ignition switch to OFF position. Disconnect the negative battery cable at the battery. Disconnect the underhood junction block harness connector that contains the relay coil ground circuit. Check the ignition relay coil ground circuit at the underhood junction block harness connector for a high resistance or for an open. Did you find and correct the condition? If yes, go to step 36 . If no, go to step 35 .
27. Turn ignition switch to OFF position. Jumper the ignition relay battery positive voltage circuit and the ignition relay load circuit together at the underhood junction block using a 20-amp fused jumper wire. Probe the following fuses using a test light connected to a good ground: OXY SEN ELEK IGN F/INJR TRANS ENG EMIS 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 35 .
28. Remove the A/C clutch relay from the underhood junction block using the relay puller pliers. Probe the A/C clutch relay ignition 1 voltage circuit using a test light that is connected to a good ground. Does the test light illuminate? If yes, go to next step. If no, go to step 35 .
29. Check for an intermittent and for a poor connection at the underhood junction block, ignition relay connector location. Did you find and correct the condition? If yes, go to step 35 . If no, go to step 32 .
30. Repair the short to battery positive voltage in the ignition 1 voltage circuit between the ignition switch and the I/P fuse block. After repair, go to step 36 .
31. Repair the short to battery positive voltage in the ignition 1 voltage circuit between the I/P fuse block and the underhood junction block harness connector.
32. Replace the ignition relay. After repair, go to step 36 .
33. Replace the ignition switch. After repair, go to step 36 .
34. Replace the A/C clutch relay. After repair, go to step 36 .
35. Replace the underhood electrical center. After repair, go to next step.
36. 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 «ENGINE CRANKS BUT DOES NOT RUN»(/buick/park-avenue/ii-2002-2005/remont/testing-diagnostics/#engine-controls-basic-diagnostic-procedures-38l__engine-cranks-but-does-not-run) under NO START DIAGNOSTICS in BASIC DIAGNOSTICS - 3.8L BONNEVILLE, GRAND PRIX, IMPALA, LESABRE, MONTE CARLO, PARK AVENUE & REGAL article.
37. Clear the DTCs using a scan tool. Operate the vehicle for 5 minutes. Does a DTC set during this ignition cycle? If yes, go to «DIAGNOSTIC TROUBLE CODE DEFINITIONS»(/buick/park-avenue/ii-2002-2005/remont/testing-diagnostics/#engine-control-system-self-diagnostics-38l__diagnostic-trouble-code-definitions) in SELF-DIAGNOSTICS - 3.8L BONNEVILLE, GRAND PRIX, IMPALA, LESABRE, MONTE CARLO, PARK AVENUE & REGAL article. If no, go to next step.

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. Perform powertrain diagnostic system check prior to testing, and after completing any repairs. See DIAGNOSTIC SYSTEM CHECK - ENGINE CONTROLS under SELF-DIAGNOSTIC SYSTEM in SELF-DIAGNOSTICS - 3.8L BONNEVILLE, GRAND PRIX, IMPALA, LESABRE, MONTE CARLO, PARK AVENUE & REGAL article.

Note. For component location, see COMPONENT LOCATIONS .

FUEL SYSTEM PRESSURE RELEASE

Pressure Release Procedure

1. Disconnect the negative battery cable to avoid possible fuel discharge if an accidental attempt is made to start the engine.
2. Remove the fuel injector sight shield. For models not equipped with a supercharger (VIN K), go to next step. For models equipped with a supercharger (VIN 1), go to step 4.
3. Remove oil filler neck. Lift the front of the shield up and pull towards the front of the vehicle. (Scheme 400) Remove fuel injector sight shield. Go to step 6.
4. Clean the area around the oil fill cap/tube before removing the tube/oil fill cap to prevent contaminants from falling into the valve rocker arm cover opening.
5. Twist counter-clockwise to unlock the oil fill cap/tube from the valve rocker arm cover. Remove nut at center of cover. Lift the fuel injector sight shield up at the front and slide the tab out of the engine bracket. (Scheme 400) Replace the oil fill cap/tube in the valve rocker arm cover. Go to next step.
6. Loosen the fuel filler cap to relieve tank vapor pressure.
7. Connect Fuel Pressure Gauge (J 34730-1A), or equivalent, to the fuel pressure connection, located on the fuel rail. (Scheme 401) Wrap a shop towel around the fuel pressure connection while connecting the fuel pressure gauge to avoid spillage.
8. Install the bleed hose into an approved container and open the valve to bleed the system pressure. The fuel connections are now safe for servicing.
9. Drain any fuel remaining in the fuel pressure gauge into an approved container.

Scheme 400

Scheme 401

Fuel Pump Circuit

See FUEL PUMP ELECTRICAL CIRCUIT DIAGNOSIS under FUEL SYSTEMS in BASIC DIAGNOSTIC PROCEDURES - 3.8L BONNEVILLE, GRAND PRIX, IMPALA, LESABRE, MONTE CARLO, PARK AVENUE & REGAL article.

Fuel Pressure Regulator

See FUEL SYSTEM DIAGNOSIS under FUEL SYSTEMS in BASIC DIAGNOSTIC PROCEDURES - 3.8L BONNEVILLE, GRAND PRIX, IMPALA, LESABRE, MONTE CARLO, PARK AVENUE & REGAL article.

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 more than 10 percent in the 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.

Testing Procedure

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

1. Using a 3.38 oz. (100 ml) specified cylinder with 0.034 oz. (1 ml) graduation marks, fill the cylinder with fuel to the 3.04 oz. (90 ml) mark.
2. Add 0.34 oz. (10 ml) of water to bring the total fluid volume to 3.38 oz. (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. Re-install the stopper and shake the cylinder vigorously again for 10-15 seconds.
6. Put the cylinder on a level surface for about 5 minutes to allow adequate liquid separation.

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

Particulate Contaminants In Fuel Testing Procedure

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

1. Using an approved fuel container, draw about 0.53 qt. (0.5 liter) of fuel.
2. Place the cylinder on a level surface for about 5 minutes to allow settling of the particulate contamination.
3. Particulate contamination will show up in various shapes and colors. Sand will typically be identified by a White or Light Brown crystals. Rubber will appear as Black and irregular particles.
4. Observe the fuel sample. If any physical contaminants or water are present, clean the fuel system. See «FUEL SYSTEM CLEANING»(/buick/park-avenue/ii-2002-2005/remont/testing-diagnostics/#engine-controls-system-component-testing-38l__fuel-system-cleaning) .

Fuel quality can affect vehicle performance. Gasoline and gasoline blends that are contaminated or contain excessive amounts of alcohol can affect vehicle driveability, fuel economy, fuel system components and emissions. Excessive alcohol in the fuel may cause fuel system corrosion, deterioration of rubber components, and subsequent fuel filter restriction. Some types of alcohol are more detrimental to fuel system components than others. Ethanol is commonly used in gasoline, but in concentrations of no more than 10 percent. Some fuels, such as E85, contain a very high percentage of ethanol. Fuel with more than 10 percent ethanol may cause driveability conditions in vehicles such as hesitation, lack of power, stalling, or no start. If excessive alcohol in the fuel is suspected, then use the following procedure to test the fuel quality.

Test Procedure

Note. Numbers in parenthesis in the following steps correspond to components in referenced figures.

1. Turn Fuel Composition Tester (J 44175) on.
2. Verify the fuel composition tester is operational by measuring the AC frequency output using a DVOM. A frequency without a fuel sample in the test cell indicates that the tester is working correctly.
3. Install Fuel Pressure Gauge (J 34730-A), or equivalent.
4. Close the bleed valve on the fuel pressure gauge.
5. Place the bleed hose (1) of the fuel pressure gauge into the 100 ml beaker (2). (Scheme 402)
6. Using a scan tool, command the fuel pump ON.
7. Slowly open the bleed valve on the fuel pressure gauge, until an adequate fuel sample is obtained.
8. If water appears in the fuel sample, replace the fuel in the vehicle. See «FUEL SYSTEM CLEANING»(/buick/park-avenue/ii-2002-2005/remont/testing-diagnostics/#engine-controls-system-component-testing-38l__fuel-system-cleaning).
9. Pour the fuel sample from the beaker (1) into the Fuel Composition Tester until the level of the fuel is at the top of each fuel test port (2). (Scheme 403)
10. Observe the diagnostic LEDs on the fuel composition tester. If the Red fuel diagnostic LED is illuminated, a fuel contamination condition exists. See «FUEL SYSTEM CLEANING»(/buick/park-avenue/ii-2002-2005/remont/testing-diagnostics/#engine-controls-system-component-testing-38l__fuel-system-cleaning).
11. Measure the output frequency of the fuel composition tester.
12. Subtract 50 from the reading on the DVOM to obtain the percentage of alcohol in the fuel sample. See examples in «FUEL COMPOSITION TEST EXAMPLES»(/buick/park-avenue/ii-2002-2005/remont/testing-diagnostics/#engine-controls-system-component-testing-38l) table.
13. If the fuel sample contains more than 10 percent ethanol, replace the fuel in the vehicle.

FUEL COMPOSITION TEST EXAMPLES

Scheme 402

Scheme 403

FUEL INJECTOR CIRCUIT DIAGNOSIS (GRAND PRIX & PARK AVENUE)

Note. For circuit identification, see WIRING DIAGRAMS . For component location, see COMPONENT LOCATIONS For connector terminal identification, see CONNECTOR IDENTIFICATION in SELF-DIAGNOSTICS - 3.8L BONNEVILLE, GRAND PRIX, IMPALA, LESABRE, MONTE CARLO, PARK AVENUE & REGAL article.

Note. For fuel injector circuit diagnosis on Impala and Monte Carlo, see FUEL INJECTOR CIRCUIT DIAGNOSIS (IMPALA & MONTE CARLO) . For fuel injector circuit diagnosis on Regal, see FUEL INJECTOR CIRCUIT DIAGNOSIS (REGAL) . Fuel injector circuit diagnosis information for Bonneville and LeSabre is not available from manufacturer.

The Powertrain Control Module (PCM) enables the appropriate fuel injector on the intake stroke for each cylinder. An individual ignition 1 voltage is supplied directly to each of 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 ground on the fuel injector ignition 1 voltage supply circuit.

1. Perform Diagnostic System Check - Engine Controls. See «DIAGNOSTIC SYSTEM CHECK - ENGINE CONTROLS»(/buick/park-avenue/ii-2002-2005/remont/testing-diagnostics/#engine-control-system-self-diagnostics-38l) under SELF-DIAGNOSTIC SYSTEM in SELF-DIAGNOSTICS - 3.8L BONNEVILLE, GRAND PRIX, IMPALA, LESABRE, MONTE CARLO, PARK AVENUE & REGAL 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»(/buick/park-avenue/ii-2002-2005/remont/testing-diagnostics/#engine-control-system-self-diagnostics-38l__dtc-p0201-p0206-injector-control-circuit) under DIAGNOSTIC TESTS in SELF-DIAGNOSTICS - 3.8L BONNEVILLE, GRAND PRIX, IMPALA, LESABRE, MONTE CARLO, PARK AVENUE & REGAL article. If no, go to next step.
3. Check the fuel injector fuse. Is the fuel injector fuse open? If yes, go to next step. If no, go to «DTC P0341: CAMSHAFT POSITION SENSOR PERFORMANCE»(/buick/park-avenue/ii-2002-2005/remont/testing-diagnostics/#engine-control-system-self-diagnostics-38l__dtc-p0341-camshaft-position-sensor-performance) under DIAGNOSTIC TESTS in SELF-DIAGNOSTICS - 3.8L BONNEVILLE, GRAND PRIX, IMPALA, LESABRE, MONTE CARLO, PARK AVENUE & REGAL article.
4. Turn ignition switch to OFF position. Disconnect a fuel injector harness connector. Probe the fuel injector ignition 1 voltage supply circuit using a test light connected to battery voltage. Does the test light illuminate? If yes, go to next step. If no, go to step 6 .
5. Check the fuel injector ignition 1 voltage supply circuit, between the fuel injector fuse and the fuel injectors for a short to ground. Did you find and correct the condition? If yes, go to step 7 . If no, go to «DIAGNOSTIC AIDS»(/buick/park-avenue/ii-2002-2005/remont/testing-diagnostics/#engine-controls-system-component-testing-38l__diagnostic-aids) .
6. Check for poor connections at the fuel injectors harness connector. Did you find and correct the condition? If yes, go to next step. If no, go to «DIAGNOSTIC AIDS»(/buick/park-avenue/ii-2002-2005/remont/testing-diagnostics/#engine-controls-system-component-testing-38l__diagnostic-aids) .
7. 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 .

Diagnostic Aids

1. Monitoring the fuel injector circuit status using a scan tool while moving the fuel injector harness may help to isolate an intermittent condition.
2. Performing the Fuel Injector Coil Test may help isolate an intermittent condition. See «FUEL INJECTOR COIL TEST»(/buick/park-avenue/ii-2002-2005/remont/testing-diagnostics/#engine-controls-system-component-testing-38l__fuel-injector-coil-test) .
3. For an intermittent condition, see «INTERMITTENTS»(/buick/park-avenue/ii-2002-2005/remont/testing-diagnostics/#engine-controls-troubleshooting-no-codes-38l__intermittents) in TROUBLESHOOTING - NO CODES - 3.8L BONNEVILLE, GRAND PRIX, IMPALA, LESABRE, MONTE CARLO, PARK AVENUE & REGAL article.

FUEL INJECTOR CIRCUIT DIAGNOSIS (IMPALA & MONTE CARLO)

Note. For circuit identification, see WIRING DIAGRAMS . For component location, see COMPONENT LOCATIONS . For connector terminal identification, see CONNECTOR IDENTIFICATION in SELF-DIAGNOSTICS - 3.8L BONNEVILLE, GRAND PRIX, IMPALA, LESABRE, MONTE CARLO, PARK AVENUE & REGAL article.

Note. For fuel injector circuit diagnosis on Grand Prix and Park Avenue, see FUEL INJECTOR CIRCUIT DIAGNOSIS (GRAND PRIX & PARK AVENUE) . For fuel injector circuit diagnosis on Regal, see FUEL INJECTOR CIRCUIT DIAGNOSIS (REGAL) . Fuel injector circuit diagnosis information for Bonneville and LeSabre is not available from manufacturer.

The Powertrain Control Module (PCM) enables the appropriate fuel injector on the intake stroke for each cylinder. An ignition 1 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 ignition 1 voltage supply circuit between the fuel injector fuse and the multi-way connector.
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»(/buick/park-avenue/ii-2002-2005/remont/testing-diagnostics/#engine-control-system-self-diagnostics-38l) under SELF-DIAGNOSTIC SYSTEM in SELF-DIAGNOSTICS - 3.8L BONNEVILLE, GRAND PRIX, IMPALA, LESABRE, MONTE CARLO, PARK AVENUE & REGAL 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»(/buick/park-avenue/ii-2002-2005/remont/testing-diagnostics/#engine-control-system-self-diagnostics-38l__dtc-p0201-p0206-injector-control-circuit) under DIAGNOSTIC TESTS in SELF-DIAGNOSTICS - 3.8L BONNEVILLE, GRAND PRIX, IMPALA, LESABRE, MONTE CARLO, PARK AVENUE & REGAL article. If no, go to next step.
3. Check the fuel injector fuse. 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 supply 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 supply 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 10 .
7. Turn ignition switch to OFF position. Check for continuity between the ignition 1 voltage supply terminal and a fuel injector terminal, at the multi-way harness connector, fuel injector side. Does the DVOM display infinity? If yes, go to next step. If no, go to step 10 .
8. Check the fuel injector ignition 1 voltage supply 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 «DIAGNOSTIC AIDS»(/buick/park-avenue/ii-2002-2005/remont/testing-diagnostics/#engine-controls-system-component-testing-38l) .
9. Repair the short to ground in the fuel injector ignition 1 voltage supply circuit. After repair, go to step 14 .
10. Repair the open in the ignition 1 voltage supply circuit between the Underhood Bussed Electrical Center (UBEC) and the splice S109, located in the engine wiring harness, top of engine, at the IAT sensor breakout. After repair, go to step 14 .
11. Repair the fuel injector ignition 1 voltage supply 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 1 voltage supply circuit. After repair, go to next step.
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 .

1. Monitoring the fuel injector circuit status using a scan tool while moving the fuel injector harness may help to isolate an intermittent condition.
2. Performing the Fuel Injector Coil Test may help isolate an intermittent condition. See «FUEL INJECTOR COIL TEST»(/buick/park-avenue/ii-2002-2005/remont/testing-diagnostics/#engine-controls-system-component-testing-38l__fuel-injector-coil-test) .
3. For an intermittent condition, see «INTERMITTENTS»(/buick/park-avenue/ii-2002-2005/remont/testing-diagnostics/#engine-controls-troubleshooting-no-codes-38l__intermittents) in TROUBLESHOOTING - NO CODES - 3.8L BONNEVILLE, GRAND PRIX, IMPALA, LESABRE, MONTE CARLO, PARK AVENUE & REGAL article.

FUEL INJECTOR CIRCUIT DIAGNOSIS (REGAL)

Note. For circuit identification, see WIRING DIAGRAMS . For component location, see COMPONENT LOCATIONS . For connector terminal identification, see CONNECTOR IDENTIFICATION in SELF-DIAGNOSTICS - 3.8L BONNEVILLE, GRAND PRIX, IMPALA, LESABRE, MONTE CARLO, PARK AVENUE & REGAL article.

Note. For fuel injector circuit diagnosis on Grand Prix and Park Avenue, see FUEL INJECTOR CIRCUIT DIAGNOSIS (GRAND PRIX & PARK AVENUE) . For fuel injector circuit diagnosis on Impala and Monte Carlo, see FUEL INJECTOR CIRCUIT DIAGNOSIS (IMPALA & MONTE CARLO) . Fuel injector circuit diagnosis information for Bonneville and LeSabre is not available from manufacturer.

The Powertrain Control Module (PCM) enables the appropriate fuel injector on the intake stroke for each cylinder. An ignition 1 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 an open ignition 1 voltage supply circuit between the injector fuse and a fuel injector harness connector.

1. Perform Diagnostic System Check - Engine Controls. See «DIAGNOSTIC SYSTEM CHECK - ENGINE CONTROLS»(/buick/park-avenue/ii-2002-2005/remont/testing-diagnostics/#engine-control-system-self-diagnostics-38l) under SELF-DIAGNOSTIC SYSTEM in SELF-DIAGNOSTICS - 3.8L BONNEVILLE, GRAND PRIX, IMPALA, LESABRE, MONTE CARLO, PARK AVENUE & REGAL 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»(/buick/park-avenue/ii-2002-2005/remont/testing-diagnostics/#engine-control-system-self-diagnostics-38l__dtc-p0201-p0206-injector-control-circuit) under DIAGNOSTIC TESTS in SELF-DIAGNOSTICS - 3.8L BONNEVILLE, GRAND PRIX, IMPALA, LESABRE, MONTE CARLO, PARK AVENUE & REGAL article.
3. Check the fuel injector fuse. Is the fuel injector fuse open? If yes, go to next step. If no, go to step 5 .
4. Turn ignition switch to OFF position. Disconnect a fuel injector harness connector. Turn ignition switch to RUN position, engine OFF. Probe the fuel injector ignition 1 voltage supply circuit using a test light connected to battery voltage. Does the test light illuminate? If yes, go to step 6 . If no, go to «DIAGNOSTIC AIDS»(/buick/park-avenue/ii-2002-2005/remont/testing-diagnostics/#engine-controls-system-component-testing-38l) .
5. Turn ignition switch to OFF position. Disconnect a harness connector of a fuel injector. Turn ignition switch to RUN position, engine OFF. Probe the fuel injector ignition 1 voltage supply circuit using a test light connected to a good ground. Does the test light illuminate? If yes, go to «DTC P0341: CAMSHAFT POSITION SENSOR PERFORMANCE»(/buick/park-avenue/ii-2002-2005/remont/testing-diagnostics/#engine-control-system-self-diagnostics-38l__dtc-p0341-camshaft-position-sensor-performance) under DIAGNOSTIC TESTS in SELF-DIAGNOSTICS - 3.8L BONNEVILLE, GRAND PRIX, IMPALA, LESABRE, MONTE CARLO, PARK AVENUE & REGAL article. If no, go to step 7 .
6. Check each fuel injector ignition 1 voltage supply circuit for a short to ground. Replace the fuse. After repair, go to step 8 .
7. Repair the open or poor connection in the fuel injectors ignition 1 voltage supply circuit. After repair, go to next step.
8. 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 .

1. Monitoring the fuel injector circuit status using a scan tool while moving the fuel injector harness may help to isolate an intermittent condition.
2. Performing the Fuel Injector Coil Test may help isolate an intermittent condition. See «FUEL INJECTOR COIL TEST»(/buick/park-avenue/ii-2002-2005/remont/testing-diagnostics/#engine-controls-system-component-testing-38l__fuel-injector-coil-test) .
3. For an intermittent condition, see «INTERMITTENTS»(/buick/park-avenue/ii-2002-2005/remont/testing-diagnostics/#engine-controls-troubleshooting-no-codes-38l__intermittents) in TROUBLESHOOTING - NO CODES - 3.8L BONNEVILLE, GRAND PRIX, IMPALA, LESABRE, MONTE CARLO, PARK AVENUE & REGAL article.

FUEL INJECTOR BALANCE TEST WITH SPECIAL TOOL

Note. For circuit identification, see WIRING DIAGRAMS . For component location, see COMPONENT LOCATIONS . For connector terminal identification, see CONNECTOR IDENTIFICATION in SELF-DIAGNOSTICS - 3.8L BONNEVILLE, GRAND PRIX, IMPALA, LESABRE, MONTE CARLO, PARK AVENUE & REGAL 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.

Fuel Injector Balance Test Example (Typical)

FUEL INJECTOR BALANCE TEST EXAMPLE (TYPICAL)

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»(/buick/park-avenue/ii-2002-2005/remont/testing-diagnostics/#engine-control-system-self-diagnostics-38l) under SELF-DIAGNOSTIC SYSTEM in SELF-DIAGNOSTICS - 3.8L BONNEVILLE, GRAND PRIX, IMPALA, LESABRE, MONTE CARLO, PARK AVENUE & REGAL 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, see «FUEL INJECTOR COIL TEST»(/buick/park-avenue/ii-2002-2005/remont/testing-diagnostics/#engine-controls-system-component-testing-38l__fuel-injector-coil-test).
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. Turn OFF all accessories. Install Fuel Pressure Gauge (J 34730-A), or equivalent. Turn ignition switch to RUN position, engine OFF. Command the fuel pump ON using a scan tool. The fuel pump may need to be commanded 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 (364-405 kPa) on models not equipped with a supercharger (VIN K), or 48-54 psi (334-375 kPa) on models equipped with a supercharger (VIN 1)? If yes, go to next step. If no, see «FUEL SYSTEM DIAGNOSIS»(/buick/park-avenue/ii-2002-2005/remont/testing-diagnostics/#engine-controls-basic-diagnostic-procedures-38l__fuel-system-diagnosis) under FUEL SYSTEM in BASIC DIAGNOSTIC PROCEDURES - 3.8L BONNEVILLE, GRAND PRIX, IMPALA, LESABRE, MONTE CARLO, PARK AVENUE & REGAL article.
5. Monitor the fuel pressure gauge for one minute. Does the fuel pressure decrease by more than 5 psi (34 kPa)? If yes, see «FUEL SYSTEM DIAGNOSIS»(/buick/park-avenue/ii-2002-2005/remont/testing-diagnostics/#engine-controls-basic-diagnostic-procedures-38l__fuel-system-diagnosis) under FUEL SYSTEM in BASIC DIAGNOSTIC PROCEDURES - 3.8L BONNEVILLE, GRAND PRIX, IMPALA, LESABRE, MONTE CARLO, PARK AVENUE & REGAL article. If no, go to next step.
6. Connect Fuel Injector Tester (J 39021, use J 39021-380 if supercharged), or equivalent. 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 after the fuel injector stops pulsing. This is the second pressure reading. (Scheme 404) 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, diagnose by symptom. See «SYMPTOMS»(/buick/park-avenue/ii-2002-2005/remont/testing-diagnostics/#engine-controls-troubleshooting-no-codes-38l__symptoms) in TROUBLE SHOOTING - NO CODES - 3.8L BONNEVILLE, GRAND PRIX, IMPALA, LESABRE, MONTE CARLO, PARK AVENUE & REGAL article.
7. Clean the fuel injectors. See «FUEL INJECTOR CLEANING»(/buick/park-avenue/ii-2002-2005/remont/testing-diagnostics/#engine-controls-system-component-testing-38l__fuel-injector-cleaning). Did you complete the action? After repair, go to next step.
8. Operate the system to verify the repair. Did you correct the condition? If yes, system is okay at this time. If no, diagnose by symptom. See «SYMPTOMS»(/buick/park-avenue/ii-2002-2005/remont/testing-diagnostics/#engine-controls-troubleshooting-no-codes-38l__symptoms) in TROUBLE SHOOTING - NO CODES - 3.8L BONNEVILLE, GRAND PRIX, IMPALA, LESABRE, MONTE CARLO, PARK AVENUE & REGAL article.

Scheme 404

FUEL INJECTOR BALANCE TEST WITH TECH 2®

Note. For circuit identification, see WIRING DIAGRAMS . For component location, see COMPONENT LOCATIONS . For connector terminal identification, see CONNECTOR IDENTIFICATION in SELF-DIAGNOSTICS - 3.8L BONNEVILLE, GRAND PRIX, IMPALA, LESABRE, MONTE CARLO, PARK AVENUE & REGAL 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. 4 - The fuel pressure should be within the specified range. Refer to Fuel System Diagnosis if the fuel pressure is not within the specified range.
3. 5 - The fuel pressure should reach a steady value. Refer to Fuel System Diagnosis if the fuel pressure does not stabilize.
4. 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. Calculate the pressure drop value for each fuel injector by subtracting the second pressure reading from the first pressure reading.

1. Perform Diagnostic System Check - Engine Controls. See «DIAGNOSTIC SYSTEM CHECK - ENGINE CONTROLS»(/buick/park-avenue/ii-2002-2005/remont/testing-diagnostics/#engine-control-system-self-diagnostics-38l) under SELF-DIAGNOSTIC SYSTEM in SELF-DIAGNOSTICS - 3.8L BONNEVILLE, GRAND PRIX, IMPALA, LESABRE, MONTE CARLO, PARK AVENUE & REGAL 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»(/buick/park-avenue/ii-2002-2005/remont/testing-diagnostics/#engine-controls-system-component-testing-38l__fuel-injector-coil-test) .
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. Turn OFF all accessories. Install Fuel Pressure Gauge (J 34730-A), or equivalent. Turn ignition switch to RUN position, engine OFF. Command the fuel pump ON using a scan tool. The fuel pump may need to be commanded 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 (364-405 kPa) on models without supercharger (VIN K), or 48-54 psi (334-375 kPa) on models with supercharger (VIN 1)? If yes, go to next step. If no, see «FUEL SYSTEM DIAGNOSIS»(/buick/park-avenue/ii-2002-2005/remont/testing-diagnostics/#engine-controls-basic-diagnostic-procedures-38l__fuel-system-diagnosis) under FUEL SYSTEM in BASIC DIAGNOSTIC PROCEDURES - 3.8L BONNEVILLE, GRAND PRIX, IMPALA, LESABRE, MONTE CARLO, PARK AVENUE & REGAL article.
5. Monitor the fuel pressure gauge for one minute. Does the fuel pressure decrease by more than 5 psi (34 kPa)? If yes, see «FUEL SYSTEM DIAGNOSIS»(/buick/park-avenue/ii-2002-2005/remont/testing-diagnostics/#engine-controls-basic-diagnostic-procedures-38l__fuel-system-diagnosis) under FUEL SYSTEM in BASIC DIAGNOSTIC PROCEDURES - 3.8L BONNEVILLE, GRAND PRIX, IMPALA, LESABRE, MONTE CARLO, PARK AVENUE & REGAL article. 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 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 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, diagnose by symptom. See «SYMPTOMS»(/buick/park-avenue/ii-2002-2005/remont/testing-diagnostics/#engine-controls-troubleshooting-no-codes-38l__symptoms) in TROUBLE SHOOTING - NO CODES - 3.8L BONNEVILLE, GRAND PRIX, IMPALA, LESABRE, MONTE CARLO, PARK AVENUE & REGAL article.
7. Replace the affected fuel injectors. After repair, go to next step.
8. Operate the system to verify the repair. Did you correct the condition? If yes, system is okay at this time. If no, diagnose by symptom. See «SYMPTOMS»(/buick/park-avenue/ii-2002-2005/remont/testing-diagnostics/#engine-controls-troubleshooting-no-codes-38l__symptoms) in TROUBLE SHOOTING - NO CODES - 3.8L BONNEVILLE, GRAND PRIX, IMPALA, LESABRE, MONTE CARLO, PARK AVENUE & REGAL article.

FUEL INJECTOR COIL TEST

Note. For circuit identification, see WIRING DIAGRAMS . For component location, see COMPONENT LOCATIONS . For connector terminal identification, see CONNECTOR IDENTIFICATION in SELF-DIAGNOSTICS - 3.8L BONNEVILLE, GRAND PRIX, IMPALA, LESABRE, MONTE CARLO, PARK AVENUE & REGAL 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. 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 resistance of the fuel injector coil windings will increase as the temperature of the fuel injector increases.

The numbers below refer to the step numbers in 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. 5 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»(/buick/park-avenue/ii-2002-2005/remont/testing-diagnostics/#engine-control-system-self-diagnostics-38l) under SELF-DIAGNOSTIC SYSTEM in SELF-DIAGNOSTICS - 3.8L BONNEVILLE, GRAND PRIX, IMPALA, LESABRE, MONTE CARLO, PARK AVENUE & REGAL article. After performing Diagnostic System Check - Engine Controls, go to next step.
2. Using scan tool, check Engine Coolant Temperature (ECT) sensor parameter. Is the ECT sensor parameter 50-90°F (10-32°C)? If yes, go to next step. If no, go to step 4 .
3. Measure the resistance of each fuel injector using a DVOM. Do any of the fuel injectors display a resistance outside 11-14 ohms? If yes, go to step 6 . If no, see «DIAGNOSTIC AIDS»(/buick/park-avenue/ii-2002-2005/remont/testing-diagnostics/#engine-controls-system-component-testing-38l) .
4. Disconnect fuel injector connector. Using DVOM, measure resistance of each fuel injector. Record each fuel injector value. Subtract lowest resistance value from highest resistance value. Is the difference equal to, or less than, 3 ohms? If yes, see «FUEL INJECTOR BALANCE TEST WITH SPECIAL TOOL»(/buick/park-avenue/ii-2002-2005/remont/testing-diagnostics/#engine-controls-system-component-testing-38l__fuel-injector-balance-test-with-special) or «FUEL INJECTOR BALANCE TEST WITH TECH 2®»(/buick/park-avenue/ii-2002-2005/remont/testing-diagnostics/#engine-controls-system-component-testing-38l__fuel-injector-balance-test-with-tech) . If no, go to next step.
5. Add all fuel injector resistance values, to obtain total resistance value. Divide total resistance value by number of fuel injectors, to obtain average resistance value. Subtract lowest and highest individual fuel injector resistance values from average resistance value. Replace fuel injector with greatest resistance difference, above or below average. Repair as necessary. After repairs, go to step 7 .
6. If resistance of fuel injector(s) is not 11-14 ohms, replace fuel injector(s). After repairs, go to next step.
7. Operate system to verify 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 that is causing the condition.
2. Operating the vehicle over a wide temperature range may help isolate the fuel injector that is causing the condition.
3. Perform the fuel injector coil test within the conditions of the customers concern. A fuel injector condition may only be apparent at a certain temperature, or under certain conditions.
4. If the fuel injector coil test does not isolate the condition, perform the fuel injector balance test. See «FUEL INJECTOR BALANCE TEST WITH SPECIAL TOOL»(/buick/park-avenue/ii-2002-2005/remont/testing-diagnostics/#engine-controls-system-component-testing-38l__fuel-injector-balance-test-with-special) or «FUEL INJECTOR BALANCE TEST WITH TECH 2®»(/buick/park-avenue/ii-2002-2005/remont/testing-diagnostics/#engine-controls-system-component-testing-38l__fuel-injector-balance-test-with-tech) .

Manufacturer does not provide testing procedures for many individual systems and components. Fuel pump relay is located in underhood fuse/relay block. To test fuel pump relay, see FUEL PUMP ELECTRICAL CIRCUIT DIAGNOSIS in BASIC DIAGNOSTIC PROCEDURES - 3.8L BONNEVILLE, GRAND PRIX, IMPALA, LESABRE, MONTE CARLO, PARK AVENUE & REGAL article.

FUEL INJECTOR CLEANING

Note. During this procedure you will need a total of 32.4 oz. (960 ml) of cleaning solution. That is 2 tanks of solution for the fuel injector cleaner. Other brands of tools may have a different capacity and would therefore require more or less tanks to complete the procedure. You must use all 32.4 oz. (960 ml) of solution to ensure complete injector cleaning.

Cleaning Procedure

1. Obtain Fuel Injector Cleaner (J 38500-A), or equivalent. Ensure shut-off valve at bottom of the canister is closed. (Scheme 405)
2. For US dealers, empty 2 pre-measured GM Top-Engine Cleaner containers, 0.812 oz. (24 ml) each (GM P/N 12346535), 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. (960 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 and disconnecting the oil pressure switch harness connector, if equipped.
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 Fuel Line Shut-Off Adapters (J 37287), or 3/8 Fuel Line Shut-Off Adapter (J 42964-1), and 5/16 Fuel Line Shut-Off Adapter (J 42964-2), or 3/8 Fuel Line Shut-Off Adapter (J 42873-1) and 5/16 Fuel Line Shut-Off Adapter (J 42873-2) 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 of fuel. This should take about 15-20 minutes.
11. Disconnect fuel injector cleaner from the fuel rail.
12. Reconnect the vehicle's fuel pump relay and oil pressure switch harness connector, if equipped.
13. Remove Fuel Line Shut-Off Adapters and reconnect the vehicles fuel feed and return lines.
14. Start and idle the engine 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. See «FUEL INJECTOR BALANCE TEST WITH SPECIAL TOOL»(/buick/park-avenue/ii-2002-2005/remont/testing-diagnostics/#engine-controls-system-component-testing-38l__fuel-injector-balance-test-with-special) or «FUEL INJECTOR BALANCE TEST WITH TECH 2®»(/buick/park-avenue/ii-2002-2005/remont/testing-diagnostics/#engine-controls-system-component-testing-38l__fuel-injector-balance-test-with-tech).
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 remainder 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 405

FUEL SYSTEM CLEANING

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. See appropriate REMOVAL & INSTALLATION article.
2. Check the fuel strainer. Replace a contaminated strainer and inspect the fuel pump.
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 ensure that the removal of the water from the fuel tank is complete.
6. Allow tank to dry completely before reassembly.
7. Disconnect the fuel pipes at the fuel rail.
8. Clean the fuel pipes by applying air pressure in the opposite direction of the fuel flow.
9. Connect the fuel pipes at the fuel rail.
10. Replace the fuel filter.
11. Install the fuel sender assembly.
12. Install the fuel tank.

FUEL TANK LEAK TEST

Note. For circuit identification, see WIRING DIAGRAMS . For component location, see COMPONENT LOCATIONS . For connector terminal identification, see CONNECTOR IDENTIFICATION in SELF-DIAGNOSTICS - 3.8L BONNEVILLE, GRAND PRIX, IMPALA, LESABRE, MONTE CARLO, PARK AVENUE & REGAL 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 complete one test cycle. The Malfunction Indicator Light (MIL) will illuminate after the EVAP diagnostics complete 2 test cycles.

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

1. 1 - Perform this procedure to determine that no EVAP diagnostic DTC is present.
2. 3 - This test locates fuel leakage in the fuel pipes.
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»(/buick/park-avenue/ii-2002-2005/remont/testing-diagnostics/#engine-control-system-self-diagnostics-38l) under SELF-DIAGNOSTIC SYSTEM in SELF-DIAGNOSTICS - 3.8L BONNEVILLE, GRAND PRIX, IMPALA, LESABRE, MONTE CARLO, PARK AVENUE & REGAL article. After performing Diagnostic System Check - Engine Controls, go to next step.
2. Raise and support the vehicle. Check the fuel tank and the fuel pipes for damage or for 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 Adapter (J 41415-40), or equivalent. Connect the Evaporative Emissions System Tester (J 41413-200). Seal the EVAP system using a scan tool. DO NOT exceed 15 in. H2O. Pressurize the fuel tank using the Evaporative Emissions System Tester. 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 Evaporative Emissions System Tester. The fuel tank may need to be partially lowered. Check for leaks above the fuel level in the following locations using the Ultrasonic Leak Detector (J 41416), or equivalent: The fuel tank, the fill limiter vent valve, the pressure relief valve, and the rollover valves. The fuel sender housing and fuel sender seal. The Fuel Tank Pressure (FTP) sensor seal. The EVAP vapor pipes. The fuel fill pipe, the fuel fill hose, and the fuel fill cap. Did you locate a fuel or vapor leak? If yes, go to next step. If no, go to «DIAGNOSTIC AIDS»(/buick/park-avenue/ii-2002-2005/remont/testing-diagnostics/#engine-controls-system-component-testing-38l) .
6. Repair system as necessary.
7. Replace fuel tank.
8. Replace leaking fuel pipe.

1. Operate the vehicle under the condition of the customer's concern. Under high temperature conditions the 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 the EVAP purge is enabled, all fuel vapor release would be eliminated.
2. Moving the EVAP pipes or the fuel pipes may help find an intermittent condition.

IDLE CONTROL SYSTEMS

Note. For idle control system testing not listed, perform related DTC testing procedure. See SELF-DIAGNOSTICS - 3.8L BONNEVILLE, GRAND PRIX, IMPALA, LESABRE, MONTE CARLO, PARK AVENUE & REGAL article.

Note. Perform powertrain diagnostic system check prior to testing, and after completing any repairs. See DIAGNOSTIC SYSTEM CHECK - ENGINE CONTROLS under SELF-DIAGNOSTIC SYSTEM in SELF-DIAGNOSTICS - 3.8L BONNEVILLE, GRAND PRIX, IMPALA, LESABRE, MONTE CARLO, PARK AVENUE & REGAL article.

IDLE AIR CONTROL SYSTEM DIAGNOSIS

Note. For circuit identification, see WIRING DIAGRAMS . For component location, see COMPONENT LOCATIONS . For connector terminal identification, see CONNECTOR IDENTIFICATION in SELF-DIAGNOSTICS - 3.8L BONNEVILLE, GRAND PRIX, IMPALA, LESABRE, MONTE CARLO, PARK AVENUE & REGAL article.

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 2 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.

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

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.

1. Perform Diagnostic System Check - Engine Controls. See «DIAGNOSTIC SYSTEM CHECK - ENGINE CONTROLS»(/buick/park-avenue/ii-2002-2005/remont/testing-diagnostics/#engine-control-system-self-diagnostics-38l) under SELF-DIAGNOSTIC SYSTEM in SELF-DIAGNOSTICS - 3.8L BONNEVILLE, GRAND PRIX, IMPALA, LESABRE, MONTE CARLO, PARK AVENUE & REGAL article.
2. Set parking brake and block drive wheels. Start 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 175 RPM above the commanded RPM? If yes, see «DIAGNOSTIC AIDS»(/buick/park-avenue/ii-2002-2005/remont/testing-diagnostics/#engine-controls-system-component-testing-38l) . If no, go to next step.
3. Turn ignition switch to OFF position. Disconnect IAC valve harness connector. Connect IAC Motor Driver (J 37027-1A), or equivalent, to the IAC valve. Start 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 SPEED parameter. Did the engine speed steadily decrease to near 600 RPM and steadily increase to near 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 using the IAC motor driver during the last test? If yes, go to step 11 . If no, go to step 12 .
5. Connect a test light between one of the IAC valve control circuits and a good ground. Start engine. Observe the IAC Counts parameter using a scan tool. Command high RPM using the IAC motor driver until the IAC Counts parameter starts to increment. Command low RPM using the IAC motor driver until the IAC Counts parameter starts to increment. Return the engine speed to the DESIRED IDLE SPEED parameter. Repeat the above procedure for the other 3 IAC valve control 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 where incrementing for any of the IAC valve control circuits? If yes, go to step 9 . If no, go to next step.
7. Connect a test light between the IAC coil "A" low control circuit and the IAC coil "A" high control circuit. Observe the IAC Counts parameter using a scan tool and the test light. Command high RPM using the IAC motor driver until the IAC Counts parameter starts to increment. Command low RPM using the IAC motor driver until the IAC Counts parameter starts to increment. Return the engine speed parameter to the DESIRED IDLE SPEED parameter. Repeat the above procedure using a test light connected between the IAC coil "B" low control circuit and the IAC coil "B" high control 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 poor connection at 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 DVOM, 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. Using a DVOM, 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 intermittent and 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 DVOM, 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 PCM. See POWERTRAIN CONTROL MODULE under COMPUTERIZED ENGINE CONTROLS in appropriate REMOVAL & INSTALLATION article. Program PCM using correct vehicle software and calibration. See «POWERTRAIN CONTROL MODULE»(/buick/park-avenue/ii-2002-2005/remont/testing-diagnostics/#engine-control-system-self-diagnostics-38l) under PROGRAMMING in SELF-DIAGNOSTICS - 3.8L BONNEVILLE, GRAND PRIX, IMPALA, LESABRE, MONTE CARLO, PARK AVENUE & REGAL article. After repair, go to next step.
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 within conditions 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»(/buick/park-avenue/ii-2002-2005/remont/testing-diagnostics/#engine-control-system-self-diagnostics-38l__diagnostic-trouble-code-definitions) in SELF-DIAGNOSTICS - 3.8L BONNEVILLE, GRAND PRIX, IMPALA, LESABRE, MONTE CARLO, PARK AVENUE & REGAL article. If no, system is okay at this time.

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 Airflow (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. A high or unstable idle condition could be caused by a non-IAC system problem that can not be overcome by the IAC valve See «SYMPTOMS»(/buick/park-avenue/ii-2002-2005/remont/testing-diagnostics/#engine-controls-troubleshooting-no-codes-38l__symptoms) in TROUBLE SHOOTING - NO CODES - 3.8L BONNEVILLE, GRAND PRIX, IMPALA, LESABRE, MONTE CARLO, PARK AVENUE & REGAL article.
11. If the problem is determined to be intermittent, see «INTERMITTENTS»(/buick/park-avenue/ii-2002-2005/remont/testing-diagnostics/#engine-controls-troubleshooting-no-codes-38l__intermittents) in TROUBLE SHOOTING - NO CODES - 3.8L BONNEVILLE, GRAND PRIX, IMPALA, LESABRE, MONTE CARLO, PARK AVENUE & REGAL article.

IGNITION SYSTEMS

Note. For basic ignition system checks, see appropriate BASIC DIAGNOSTIC PROCEDURES article.

Note. For ignition system testing, perform related DTC testing procedure. See SELF-DIAGNOSTICS - 3.8L BONNEVILLE, GRAND PRIX, IMPALA, LESABRE, MONTE CARLO, PARK AVENUE & REGAL article.

See CAMSHAFT POSITION SENSOR under SENSORS & SWITCHES.

See CRANKSHAFT POSITION SENSOR under SENSORS & SWITCHES.

IGNITION COILS

Manufacturer does not provide testing procedures for many individual systems and components. See ELECTRONIC IGNITION SYSTEM DIAGNOSIS under IGNITION SYSTEM in BASIC DIAGNOSTIC PROCEDURES - 3.8L BONNEVILLE, GRAND PRIX, IMPALA, LESABRE, MONTE CARLO, PARK AVENUE & REGAL article.

EMISSION SYSTEMS & SUBSYSTEMS

Note. For emission and subsystem testing not listed, perform related DTC testing procedure. See SELF-DIAGNOSTICS - 3.8L BONNEVILLE, GRAND PRIX, IMPALA, LESABRE, MONTE CARLO, PARK AVENUE & REGAL article.

Electric AIR Pump

Note. Manufacturer does not provide testing procedures for many individual systems and components. Air injection information not available from manufacturer.

EXHAUST GAS RECIRCULATION

Note. Manufacturer does not provide testing procedures for many individual systems and components. A malfunction in EGR circuit can set a DTC. For testing procedures and specifications, perform related DTC testing procedure. See SELF-DIAGNOSTICS - 3.8L BONNEVILLE, GRAND PRIX, IMPALA, LESABRE, MONTE CARLO, PARK AVENUE & REGAL article.

EXHAUST SYSTEM CHECK

Visual/Physical Inspection

1. Check for aftermarket or non-OEM devices such as, but not including; tailpipe extensions, headers, and exhaust cutouts. This could affect the operation and proper performance of the exhaust system.
2. Verify the exact operating conditions under which the concern exists. Note factors such as engine RPM, engine temperature, engine load, and frequency of concern.
3. Check the easily accessible or visible system components for obvious damage or conditions which could cause any symptom.

Intermittent

Test the vehicle under the same conditions that the customer reported to verify the system is operating as designed.

Symptom

Refer to a symptom diagnostic procedure from the following list to diagnose the symptom

1. Loss of power, poor acceleration, poor fuel economy, or excessive smoke-diesel, see «RESTRICTED EXHAUST»(/buick/park-avenue/ii-2002-2005/remont/testing-diagnostics/#engine-controls-system-component-testing-38l) .
2. Exhaust hissing or popping, see «EXHAUST LEAKAGE»(/buick/park-avenue/ii-2002-2005/remont/testing-diagnostics/#engine-controls-system-component-testing-38l__exhaust-leakage) .
3. Rattle, buzz, groan, hum or loud noise, see «EXHAUST NOISE»(/buick/park-avenue/ii-2002-2005/remont/testing-diagnostics/#engine-controls-system-component-testing-38l__exhaust-noise) .

The numbers below refer to the step numbers in 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. Removing the HO2S sensor 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.

1. Verify the customers concern. Go to next step.
2. Did you review the exhaust system check and perform the necessary inspections? If yes, go to next step. If no, see «EXHAUST SYSTEM CHECK»(/buick/park-avenue/ii-2002-2005/remont/testing-diagnostics/#engine-controls-system-component-testing-38l__exhaust-system-check) .
3. Is the system equipped with dual exhaust? If yes, see «DIAGNOSTIC AIDS»(/buick/park-avenue/ii-2002-2005/remont/testing-diagnostics/#engine-controls-system-component-testing-38l) . If no, go to next step.
4. Remove the HO2S that is in front of the catalytic converter. Install the Exhaust Back Pressure Gauge (J 35314-A), or equivalent, in place of the HO2S sensor. 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 8 .
5. Turn the engine off and place the ignition in LOCK position. Remove the exhaust back pressure gauge. Re-install the HO2S sensor. Remove the post-catalyst HO2S 2 sensor. Install the exhaust back pressure gauge in place of the post HO2S sensor. 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. Repair as necessary. After repair, go to step 8 .
7. Replace the catalytic converter. After repair, go to next step.
8. Remove the exhaust back pressure gauge. Reinstall the applicable HO2S sensor. 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 diagnosis should begin there.

EXHAUST LEAKAGE

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. For possible cause and repair, see EXHAUST LEAKAGE DIAGNOSIS table.

EXHAUST LEAKAGE DIAGNOSIS

EXHAUST NOISE

An audible or physical noise may occur, due to a faulty component or damaged components causing a loose or misaligned exhaust system, resulting in a rattle or vibration noise, buzz, groan, hum. For possible cause and diagnosis, see EXHAUST NOISE DIAGNOSIS table.

EXHAUST NOISE DIAGNOSIS

FUEL EVAPORATE SYSTEM

Note. Ensure all vacuum line and EVAP system components are not damaged or missing.

EVAP Control System Diagnosis

For EVAP control system diagnosis, see INSPECTION/MAINTENANCE EVAPORATIVE EMISSION SYSTEM in SELF-DIAGNOSTICS - 3.8L BONNEVILLE, GRAND PRIX, IMPALA, LESABRE, MONTE CARLO, PARK AVENUE & REGAL article.

EVAPORATIVE EMISSION SYSTEM CLEANING

Note. Proceed with the following procedure only if referenced by a Evaporative Emission (EVAP) diagnostic or repair procedure.

Inspection Procedure

Note. Use the EVAP Pressure/Purge Diagnostic Station (J 41413) to provide a clean, dry, low pressure gas source. DO NOT substitute any other pressurized gas source. Damage may result to the EVAP system. Turn ignition switch to OFF position. Remove the EVAP canister purge valve. Lightly tap the EVAP canister purge valve on a hard surface. Check for carbon particles exiting either of the vacuum ports. If no carbon particles were detected, but a blockage was detected during a diagnostic procedure, install the original EVAP canister purge valve and continue with the cleaning procedure. If carbon particles are found during the inspection procedure, replace the EVAP canister purge valve and continue with the cleaning procedure. If a diagnostic procedure directed you to replace the EVAP canister purge valve and no carbon particles were detected, replace the EVAP canister purge valve and return to diagnostic procedure.

1. Raise and support vehicle.
2. Remove the EVAP canister.
3. Turn OFF the main valve on the EVAP Pressure/Purge Diagnostic Station.
4. Disconnect the hose from the diagnostic station pressure regulator.
5. Using a section of vacuum hose, connect one end onto the diagnostic station pressure regulator.
6. Connect the other end of the vacuum hose to the canister side of the purge pipe.
7. Turn ON the main nitrogen cylinder valve and continue to discharge nitrogen for 15 seconds.
8. If the nitrogen does not dislodge the carbon particles, replace the purge pipe.
9. Return the EVAP pressure/purge diagnostic station to the original condition of the station.
10. Install a new EVAP canister.
11. Lower the vehicle.
12. Install a new EVAP canister purge valve.
13. Return to diagnostic procedure that sent you here.

Diagnosis

1. External Oil Leak - Check for plugged Positive Crankcase Ventilation (PCV) valve, plugged or kinked PCV hoses, damaged or incorrectly installed PCV valve or PCV valve "O" ring, hoses or excessive crankcase pressure.
2. Rough Idle - Check for plugged PCV valve, plugged or kinked PCV hoses, leaking or damaged PCV valve or hoses.
3. Stalling Or Slow Idle Speed - Check for plugged PCV valve, plugged or kinked PCV hoses, or leaking or damaged PCV valve or hoses.
4. High Idle Speed - Check for a leaking or damaged PCV valve or hoses.
5. Sludge In The Engine - Check for plugged PCV valve or plugged or kinked PCV hoses.

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.

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 - 3.8L BONNEVILLE, GRAND PRIX, IMPALA, LESABRE, MONTE CARLO, PARK AVENUE & REGAL 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 ENGINES.

TRANSMISSION

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

BONNEVILLE

See ENGINE PERFORMANCE in SYSTEM WIRING DIAGRAMS article in ELECTRICAL.

GRAND PRIX

See ENGINE PERFORMANCE in SYSTEM WIRING DIAGRAMS article in ELECTRICAL.

IMPALA

See ENGINE PERFORMANCE in SYSTEM WIRING DIAGRAMS article in ELECTRICAL.

LESABRE

See ENGINE PERFORMANCE in SYSTEM WIRING DIAGRAMS article in ELECTRICAL.

MONTE CARLO

See ENGINE PERFORMANCE in SYSTEM WIRING DIAGRAMS article in ELECTRICAL.

PARK AVENUE

See ENGINE PERFORMANCE in SYSTEM WIRING DIAGRAMS article in ELECTRICAL.

REGAL

See ENGINE PERFORMANCE in SYSTEM WIRING DIAGRAMS article in ELECTRICAL.

See also:
• DIAGNOSTIC SYSTEM CHECK - ENGINE CONTROLS
• BASIC DIAGNOSTIC PROCEDURES - 3.8L BONNEVILLE, GRAND PRIX, IMPALA, LE SABRE, MONTE CARLO, PARK AVENUE & REGAL
• TROUBLE SHOOTING - NO CODES - 3.8L BONNEVILLE, GRAND PRIX, IMPALA, LE SABRE, MONTE CARLO, PARK AVENUE & REGAL
• DIAGNOSTIC TROUBLE CODE DEFINITIONS
• FUEL PUMP ELECTRICAL CIRCUIT DIAGNOSIS
• ELECTRONIC IGNITION SYSTEM DIAGNOSIS
• ENGINE CRANKS BUT DOES NOT RUN
• FUEL SYSTEM DIAGNOSIS
• DTC P0201-P0206: INJECTOR CONTROL CIRCUIT
• DTC P0341: CAMSHAFT POSITION SENSOR PERFORMANCE
• INTERMITTENTS
• SYMPTOMS
• COMPONENT LOCATIONS
• IDLE CONTROL SYSTEMS
• FUEL SYSTEM CLEANING
• FUEL INJECTOR CIRCUIT DIAGNOSIS (IMPALA & MONTE CARLO)
• FUEL INJECTOR CIRCUIT DIAGNOSIS (REGAL)
• DIAGNOSTIC AIDS
• FUEL INJECTOR COIL TEST
• FUEL INJECTOR CIRCUIT DIAGNOSIS (GRAND PRIX & PARK AVENUE)
• FUEL INJECTOR CLEANING
• FUEL INJECTOR BALANCE TEST WITH SPECIAL TOOL
• FUEL INJECTOR BALANCE TEST WITH TECH 2®
• CAMSHAFT POSITION SENSOR
• CRANKSHAFT POSITION SENSOR
• EXHAUST LEAKAGE
• EXHAUST NOISE
• EXHAUST SYSTEM CHECK