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Engine Controls - Basic Diagnostic Procedures - 3.4l Chevrolet Monte Carlo VI

Testing & Diagnostics 1 illustration ~2627 words

INTRODUCTION

CAUTIONWhen battery is disconnected, vehicle computer and memory systems may lose memory data. Driveability problems may exist until computer systems have completed a relearn cycle. See appropriate COMPUTER RELEARN PROCEDURES article in GENERAL INFORMATION before disconnecting battery.

Before proceeding with basic diagnostic procedures, ensure testing procedure is followed, as some systems which may result in a no-start condition may cause a Diagnostic Trouble Codes (DTC) to be stored in the Powertrain Control Module (PCM). See DIAGNOSTIC SYSTEM CHECK - ENGINE CONTROLS under SELF-DIAGNOSTIC SYSTEM in - 3.4L ALERO, GRAND AM, IMPALA & MONTE CARLO article.

If no-start condition still exists after checking and repairing all DTCs, perform a careful and complete visual inspection. Many problems result from mechanical breakdowns, poor electrical connections or damaged/misrouted vacuum hoses. Before condemning the computerized system, perform each test listed in this article.

Use intermittent test procedures to locate driveability problems that do not occur when the vehicle is being tested. These test procedures should also be used if a soft (intermittent) trouble code was present but no problem was found during self-diagnostic testing. See INTERMITTENTS in TROUBLE SHOOTING - NO-CODES - 3.4L ALERO, GRAND AM, IMPALA & MONTE CARLO article.

Note. Perform all voltage tests using a Digital Multi-Meter (DMM) or Digital Volt-Ohmmeter (DVOM) with a minimum 10-megohm input impedance, unless stated otherwise in test procedure.

Note. For specific testing procedures, go to SYSTEM & COMPONENT TESTING - 3.4L ALERO, GRAND AM, IMPALA & MONTE CARLO article. For specifications, go to appropriate ON-VEHICLE ADJUSTMENTS or appropriate SERVICE & ADJUSTMENT SPECIFICATIONS article.

VISUAL INSPECTION

Visually inspect all electrical wiring, looking for chafed, stretched, cut or pinched wiring. Ensure harness connectors fit tightly and are not corroded. Ensure vacuum hoses are properly routed and not pinched or cut. If necessary, see appropriate VACUUM DIAGRAMS article to verify routing and connections. Inspect air induction system for possible vacuum leaks or restrictions. Check for air leaks at all intake manifold sealing surfaces. Check ignition wires for cracking, hardness, proper routing and carbon tracking. Ensure PCM and MIL are functioning properly. Ensure there are no DTCs stored, or only intermittent DTCs are present.

After all checks have been performed, verify customer complaint and locate correct symptom. Check items indicated under that symptom. These procedures will normally recommend testing of a specific system or component, such as EGR, ignition, TCC, etc. Go to SYSTEM & COMPONENT TESTING - 3.4L ALERO, GRAND AM, IMPALA & MONTE CARLO article for appropriate test procedures.

MECHANICAL INSPECTION

WARNINGBecause fuel injectors on many models are triggered by ignition switch during cranking mode, do not use ignition switch during compression tests. Use a remote starter to crank engine to prevent fire hazard or engine oiling system contamination.

Compression

Check engine mechanical condition using a compression gauge, vacuum gauge, or an engine analyzer. See engine analyzer manual for specific instructions. For compression specifications, see MECHANICAL CHECKS in appropriate SERVICE & ADJUSTMENT SPECIFICATIONS article.

Exhaust System Backpressure

Before replacing any components, check exhaust system for restrictions. See RESTRICTED EXHAUST (ALERO & GRAND AM) or RESTRICTED EXHAUST (IMPALA & MONTE CARLO) under EXHAUST SYSTEMS in SYSTEM & COMPONENT TESTING - 3.4L ALERO, GRAND AM, IMPALA & MONTE CARLO article.

NO-START DIAGNOSIS

CAUTIONTo prevent damage caused by the improper probing of connector terminals, use the Connector Test Adapter Kit (J 35616-A), or equivalent, for any test that requires probing the following items: The PCM harness connectors. The electrical center fuse/relay cavities. The component terminals. The component harness connector.

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

Note. Some vehicles are equipped with anti-theft systems (VATS or PASS-Key®) which will not allow vehicle to be started if improper starting procedures or improperly coded ignition keys are used. Both fuel injection and cranking systems will be disabled. Loss of fuel enable signal from anti-theft decoder module should set a diagnostic trouble code in PCM memory.

  1. Definition - No start is defined as engine cranks properly, but does not start. Engine may fire a few times.

Symptom Definition

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

  1. The battery is completely charged.
  2. The engine cranking speed is acceptable.
  3. There is adequate fuel in the fuel tank.
  1. Perform diagnostic system check - engine controls. See «DIAGNOSTIC SYSTEM CHECK - ENGINE CONTROLS»(/chevrolet/monte-carlo/vi-1999-2007/remont/testing-diagnostics/#engine-controls-self-diagnostics-34l) in SELF-DIAGNOSTICS - 3.4L ALERO, GRAND AM, IMPALA & MONTE CARLO article. After performing diagnostic system check - engine controls, go to next step.
  2. Crank the engine for 15 seconds. Turn ignition switch to RUN position, engine OFF. Observe the DTC information using a scan tool. Does the scan tool display DTC P0101, P0123, P0230, P0336, P0601, P0602, P1626, P1630, P1631, B1369, or B1379? If yes, go to «DIAGNOSTIC TROUBLE CODE DEFINITIONS»(/chevrolet/monte-carlo/vi-1999-2007/remont/testing-diagnostics/#engine-controls-self-diagnostics-34l__diagnostic-trouble-code-definitions) in SELF-DIAGNOSTICS - 3.4L ALERO, GRAND AM, IMPALA & MONTE CARLO article. If no, go to next step.
  3. Turn the ignition switch to RUN position. Is the MIL illuminated? If yes, go to next step. If no go to «MIL INOPERATIVE»(/chevrolet/monte-carlo/vi-1999-2007/remont/testing-diagnostics/#engine-controls-self-diagnostics-34l__mil-inoperative) under SYSTEM TESTS in SELF-DIAGNOSTICS - 3.4L ALERO, GRAND AM, IMPALA & MONTE CARLO article. If no, go to next step.
  4. Command the fuel pump ON using a scan tool. Does the fuel pump turn ON? If yes, go to next step. If no, go to «FUEL PUMP ELECTRICAL CIRCUIT DIAGNOSIS (ALERO & GRAND AM)»(/chevrolet/monte-carlo/vi-1999-2007/remont/testing-diagnostics/#engine-controls-system-component-testing-34l__fuel-pump-electrical-circuit-diagnosis-alero) under FUEL SYSTEMS in SYSTEM & COMPONENT TESTING - 3.4L ALERO, GRAND AM, IMPALA & MONTE CARLO article.
  5. Turn ignition switch to OFF position. Disconnect a spark plug wire. Install Spark Tester (J 26792), or equivalent, to the spark plug wire. Attempt to start the engine. Does the spark tester spark? If yes, go to next step. If no, go to «ELECTRONIC IGNITION SYSTEM DIAGNOSIS»(/chevrolet/monte-carlo/vi-1999-2007/remont/testing-diagnostics/#engine-controls-system-component-testing-34l__electronic-ignition-system-diagnosis) under IGNITION SYSTEMS in SYSTEM & COMPONENT TESTING - 3.4L ALERO, GRAND AM, IMPALA & MONTE CARLO article.
  6. While monitoring the CYLINDER 1-6 INJECTOR CIRCUIT STATUS parameters using a scan tool, crank the engine. Do all of the cylinder injector circuit status parameters display okay while cranking the engine? If yes, go to next step. If no, go to «FUEL PUMP ELECTRICAL CIRCUIT DIAGNOSIS (ALERO & GRAND AM)»(/chevrolet/monte-carlo/vi-1999-2007/remont/testing-diagnostics/#engine-controls-system-component-testing-34l__fuel-pump-electrical-circuit-diagnosis-alero) under FUEL SYSTEMS in SYSTEM & COMPONENT TESTING - 3.4L ALERO, GRAND AM, IMPALA & MONTE CARLO article.
  7. Turn ignition switch to OFF position. Connect all disconnected components. Install Fuel Pressure Gauge (J 34730-1A), or equivalent. (Scheme 72) Turn ignition switch to RUN position, engine OFF. Command the fuel pump ON using a scan tool. Is the fuel pressure 52-59 psi (358-405 kPa) when the fuel pump is operating? If yes, go to next step. If no, go to «FUEL SYSTEM DIAGNOSIS»(/chevrolet/monte-carlo/vi-1999-2007/remont/testing-diagnostics/#engine-controls-system-component-testing-34l__fuel-system-diagnosis) under FUEL SYSTEMS in SYSTEM & COMPONENT TESTING - 3.4L ALERO, GRAND AM, IMPALA & MONTE CARLO article.
  8. Inspect for the following conditions: Collapsed air intake duct. Restricted air filter element. Spark plugs for being gas or coolant fouled. If the spark plugs are fouled, determine what caused the condition. Engine mechanical condition; worn timing chain and gears, low compression, etc. See appropriate article in ENGINES. Restricted exhaust system. Go to «RESTRICTED EXHAUST (ALERO & GRAND AM)»(/chevrolet/monte-carlo/vi-1999-2007/remont/testing-diagnostics/#engine-controls-system-component-testing-34l) under EXHAUST SYSTEMS in SYSTEM & COMPONENT TESTING - 3.4L ALERO, GRAND AM, IMPALA & MONTE CARLO article. The Engine Coolant Temperature (ECT) sensor is NOT close to the actual engine temperature. Go to «DTC P0128: ENGINE COOLANT TEMPERATURE BELOW THERMOSTAT REGULATING TEMPERATURE»(/chevrolet/monte-carlo/vi-1999-2007/remont/testing-diagnostics/#engine-controls-self-diagnostics-34l__dtc-p0128-engine-coolant-temperature-below) under DIAGNOSTIC TESTS in SELF-DIAGNOSTICS - 3.4L ALERO, GRAND AM, IMPALA & MONTE CARLO article. Compare the Manifold Absolute Pressure/Barometric Pressure (MAP/BARO) parameters to another vehicle. The parameters should be close in value. Go to «MANIFOLD ABSOLUTE PRESSURE SENSOR»(/chevrolet/monte-carlo/vi-1999-2007/remont/testing-diagnostics/#engine-controls-system-component-testing-34l__manifold-absolute-pressure-sensor) under SENSORS & SWITCHES in SYSTEM & COMPONENT TESTING - 3.4L ALERO, GRAND AM, IMPALA & MONTE CARLO article. Throttle Position (TP) sensor for being stuck in range. Go to «DTC P0121: TP SENSOR PERFORMANCE»(/chevrolet/monte-carlo/vi-1999-2007/remont/testing-diagnostics/#engine-controls-self-diagnostics-34l) under DIAGNOSTIC TESTS in SELF-DIAGNOSTICS - 3.4L ALERO, GRAND AM, IMPALA & MONTE CARLO article. Did you complete the action(s)? If yes, go to next step.
  9. Clear the DTCs using a scan tool. Attempt to start the engine. Does the engine start and continue to run? If yes, go to next step. If no, go to step 2.
  10. Allow the engine to reach operating temperature. Observe the DTC information using a scan tool. Are there any DTCs that have not been diagnosed? If yes, go to «DIAGNOSTIC TROUBLE CODE DEFINITIONS»(/chevrolet/monte-carlo/vi-1999-2007/remont/testing-diagnostics/#engine-controls-self-diagnostics-34l__diagnostic-trouble-code-definitions) in SELF-DIAGNOSTICS - 3.4L ALERO, GRAND AM, IMPALA & MONTE CARLO article. If no, system is okay at this time.

Scheme 72

Scheme 72
Scheme 72

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

  1. The battery is completely charged.
  2. The engine cranking speed is acceptable.
  3. There is adequate fuel in the fuel tank.

Test Description

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

  1. 7 - If all the Cylinder Injector Circuit Status parameters display FAULT, this indicates a condition with the injector supply voltage circuit.
  1. Perform diagnostic system check - engine controls. See «DIAGNOSTIC SYSTEM CHECK - ENGINE CONTROLS»(/chevrolet/monte-carlo/vi-1999-2007/remont/testing-diagnostics/#engine-controls-self-diagnostics-34l) in SELF-DIAGNOSTICS - 3.4L ALERO, GRAND AM, IMPALA & MONTE CARLO article. After performing diagnostic system check - engine controls, go to next step.
  2. Turn ignition switch to RUN position, engine OFF. Observe the DTC information using a scan tool. Does the scan tool display DTC P0123, P0230, P0336, P0601, P0602, P1626, P1629, P1630, or P1631? If yes, go to «DIAGNOSTIC TROUBLE CODE DEFINITIONS»(/chevrolet/monte-carlo/vi-1999-2007/remont/testing-diagnostics/#engine-controls-self-diagnostics-34l__diagnostic-trouble-code-definitions) in SELF-DIAGNOSTICS - 3.4L ALERO, GRAND AM, IMPALA & MONTE CARLO article. If no, go to next step.
  3. Turn ignition switch to RUN position, engine OFF. Probe both sides of the DFI MDL fuse (15-amp) and the FUEL INJ fuse (15-amp) using a test light connected to a good ground. Does the test light illuminate on at least one side of each fuse? If yes, go to next step. If no, go to «IGNITION RELAY DIAGNOSIS»(/chevrolet/monte-carlo/vi-1999-2007/remont/testing-diagnostics/#engine-controls-system-component-testing-34l__ignition-relay-diagnosis) under IGNITION SYSTEMS in SYSTEM & COMPONENT TESTING - 3.4L ALERO, GRAND AM, IMPALA & MONTE CARLO article.
  4. Observe the engine RPM parameter using a scan tool. Attempt to start the engine. Does the engine RPM parameter display cranking RPM? If yes, go to next step. If no, go to «ELECTRONIC IGNITION SYSTEM DIAGNOSIS»(/chevrolet/monte-carlo/vi-1999-2007/remont/testing-diagnostics/#engine-controls-system-component-testing-34l__electronic-ignition-system-diagnosis) under IGNITION SYSTEMS in SYSTEM & COMPONENT TESTING - 3.4L ALERO, GRAND AM, IMPALA & MONTE CARLO article.
  5. Command the fuel pump ON using a scan tool. Does the fuel pump turn ON? If yes, go to next step. If no, go to «FUEL PUMP ELECTRICAL CIRCUIT DIAGNOSIS (IMPALA & MONTE CARLO)»(/chevrolet/monte-carlo/vi-1999-2007/remont/testing-diagnostics/#engine-controls-system-component-testing-34l__fuel-pump-electrical-circuit-diagnosis-impala) under FUEL SYSTEMS in SYSTEM & COMPONENT TESTING - 3.4L ALERO, GRAND AM, IMPALA & MONTE CARLO article.
  6. Turn ignition switch to OFF position. Disconnect a spark plug wire. Install Spark Tester (J 26792), or equivalent, to the spark plug wire. Attempt to start the engine. Does the spark tester spark? If yes, go to next step. If no, go to «ELECTRONIC IGNITION SYSTEM DIAGNOSIS»(/chevrolet/monte-carlo/vi-1999-2007/remont/testing-diagnostics/#engine-controls-system-component-testing-34l__electronic-ignition-system-diagnosis) under IGNITION SYSTEMS in SYSTEM & COMPONENT TESTING - 3.4L ALERO, GRAND AM, IMPALA & MONTE CARLO article.
  7. While monitoring the CYLINDER 1-6 INJECTOR CIRCUIT STATUS parameter using a scan tool, crank the engine. Do all of the cylinder injector circuit status parameters display OKAY while cranking the engine? If yes, go to next step. If no, go to «FUEL PUMP ELECTRICAL CIRCUIT DIAGNOSIS (IMPALA & MONTE CARLO)»(/chevrolet/monte-carlo/vi-1999-2007/remont/testing-diagnostics/#engine-controls-system-component-testing-34l__fuel-pump-electrical-circuit-diagnosis-impala) under FUEL SYSTEMS in SYSTEM & COMPONENT TESTING - 3.4L ALERO, GRAND AM, IMPALA & MONTE CARLO article.
  8. Turn ignition switch to OFF position. Install and connect all disconnected components. Install Fuel Pressure Gauge (J 34730-1A), or equivalent. (Scheme 72) Turn ignition switch to RUN position, engine OFF. Command the fuel pump ON using a scan tool. Is the fuel pressure 52-59 psi (358-405 kPa) when the fuel pump is operating? If yes, go to next step. If no, go to «FUEL SYSTEM DIAGNOSIS»(/chevrolet/monte-carlo/vi-1999-2007/remont/testing-diagnostics/#engine-controls-system-component-testing-34l__fuel-system-diagnosis) under FUEL SYSTEMS in SYSTEM & COMPONENT TESTING - 3.4L ALERO, GRAND AM, IMPALA & MONTE CARLO article.
  9. Inspect for the following conditions: Collapsed air intake duct. Restricted air filter element. Spark plugs for being gas or coolant fouled. If the spark plugs are fouled, determine what caused the condition. Engine mechanical condition; worn timing chain and gears, low compression, etc. See appropriate article in ENGINES. Restricted exhaust system. Go to «RESTRICTED EXHAUST (IMPALA & MONTE CARLO)»(/chevrolet/monte-carlo/vi-1999-2007/remont/testing-diagnostics/#engine-controls-system-component-testing-34l) under EXHAUST SYSTEMS in SYSTEM & COMPONENT TESTING - 3.4L ALERO, GRAND AM, IMPALA & MONTE CARLO article. The Engine Coolant Temperature (ECT) sensor is NOT close to the actual engine temperature. Go to «DTC P0128: ENGINE COOLANT TEMPERATURE BELOW THERMOSTAT REGULATING TEMPERATURE»(/chevrolet/monte-carlo/vi-1999-2007/remont/testing-diagnostics/#engine-controls-self-diagnostics-34l__dtc-p0128-engine-coolant-temperature-below) under DIAGNOSTIC TESTS in SELF-DIAGNOSTICS - 3.4L ALERO, GRAND AM, IMPALA & MONTE CARLO article. Compare the Manifold Absolute Pressure/Barometric Pressure (MAP/BARO) parameters to another vehicle. The parameters should be close in value. Go to «MANIFOLD ABSOLUTE PRESSURE SENSOR»(/chevrolet/monte-carlo/vi-1999-2007/remont/testing-diagnostics/#engine-controls-system-component-testing-34l__manifold-absolute-pressure-sensor) under SENSORS & SWITCHES in SYSTEM & COMPONENT TESTING - 3.4L ALERO, GRAND AM, IMPALA & MONTE CARLO article. Throttle Position (TP) sensor for being stuck in range. Go to «DTC P0121: TP SENSOR PERFORMANCE»(/chevrolet/monte-carlo/vi-1999-2007/remont/testing-diagnostics/#engine-controls-self-diagnostics-34l) under DIAGNOSTIC TESTS in SELF-DIAGNOSTICS - 3.4L ALERO, GRAND AM, IMPALA & MONTE CARLO article. Did you complete the action(s)? If yes, go to next step.
  10. Clear the DTCs using a scan tool. Attempt to start the engine. Does the engine start and continue to operate? If yes, go to next step. If no, go to step 2.
  11. Allow the engine to reach operating temperature. Observe the DTC information using a scan tool. Are there any DTCs that have not been diagnosed? If yes, go to «DIAGNOSTIC TROUBLE CODE DEFINITIONS»(/chevrolet/monte-carlo/vi-1999-2007/remont/testing-diagnostics/#engine-controls-self-diagnostics-34l__diagnostic-trouble-code-definitions) in SELF-DIAGNOSTICS - 3.4L ALERO, GRAND AM, IMPALA & MONTE CARLO article. If no, system is okay at this time.

FUEL SYSTEMS

CAUTIONBegin fuel system trouble shooting and diagnosis with checking fuel injection system pressure. High fuel pressure may be present in fuel lines and component parts. Relieve fuel pressure before disconnecting any fuel system components.
CAUTIONTo prevent damage caused by the improper probing of connector terminals, use the Connector Test Adapter Kit (J 35616-A) for any test that requires probing the following items: The PCM harness connectors. The electrical center fuse/relay cavities. The component terminals. The component harness connector.

Note. For fuel pump circuit testing, see appropriate diagnostic procedure under NO-START DIAGNOSIS .

FUEL SYSTEM PRESSURE RELEASE

WARNINGALWAYS release fuel pressure before disconnecting any fuel injection-related component. Do NOT allow fuel to contact engine or electrical components. Before servicing any electrical component, the ignition key must be in the OFF or LOCK position and all electrical loads must be OFF, unless instructed otherwise in these procedures. If a tool or equipment could easily come in contact with a live exposed electrical terminal, also disconnect the negative battery cable. Failure to follow these precautions may cause personal injury and/or damage to the vehicle or its components.
  1. Disconnect the negative battery cable.
  2. Install the Fuel Pressure Gauge Adaptor (J 34730-262), or equivalent, to the fuel pressure connection, located on the fuel rail. (Scheme 72)
  3. Place the fuel pressure gauge bleed hose into an approved gasoline container.
  4. Open the valve to bleed the system pressure. The fuel connections are now safe for servicing.
  5. Disconnect the fuel pressure gauge from the fuel pressure connection and install the fuel pressure port cap.

FUEL PRESSURE TEST

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

IGNITION SYSTEMS

CAUTIONTo prevent damage caused by the improper probing of connector terminals, use the Connector Test Adapter Kit (J 35616-A), or equivalent, for any test that requires probing the following items: The PCM harness connectors. The electrical center fuse/relay cavities. The component terminals. The component harness connector.

Manufacturer does not provide testing procedures for many individual systems and components. For information on testing the ignition system, see IGNITION SYSTEMS in SYSTEM & COMPONENT TESTING - 3.4L ALERO, GRAND AM, IMPALA & MONTE CARLO article. For ignition system testing not listed, perform related DTC testing procedure. See SELF-DIAGNOSTICS - 3.4L ALERO, GRAND AM, IMPALA & MONTE CARLO article.

IDLE SPEED & IGNITION TIMING

Idle speed is preset by manufacturer and is not adjustable. All models are equipped with an electronic computer-controlled ignition system. Timing is not adjustable.

ALERO

See ENGINE PERFORMANCE in SYSTEM WIRING DIAGRAMS article in ELECTRICAL.

GRAND AM

See ENGINE PERFORMANCE in SYSTEM WIRING DIAGRAMS article in ELECTRICAL.

IMPALA

See ENGINE PERFORMANCE in SYSTEM WIRING DIAGRAMS article in ELECTRICAL.

MONTE CARLO

See ENGINE PERFORMANCE in SYSTEM WIRING DIAGRAMS article in ELECTRICAL.

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