Engine Control System Testing & Engine Component Testing - 2.4l Chevrolet Malibu V

MODEL IDENTIFICATION

Vehicle model is identified by fourth character of Vehicle Identification Number (VIN). VIN is stamped on metal pad on top of left end of instrument panel, near windshield.

INTRODUCTION

Before testing separate components or systems, perform all procedures listed in BASIC TESTING - 2.4L article. Since many computer-controlled and monitored components will set a diagnostic trouble code if they malfunction, it is also recommended self-diagnosis be performed. See TESTS W/CODES - 2.4L article.

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

PCM OUTPUT DIAGNOSIS

1. If powertrain OBD system check has been performed, go to next step. If powertrain OBD system check has not been performed, perform powertrain OBD system check. See POWERTRAIN OBD SYSTEM CHECK in TESTS W/CODES - 2.4L article.
2. Connect scan tool to data link connector. If a No. 1 is displayed below any of the number output drivers, go to next step. If a No. 1 is not displayed below any of the number output drivers, go to step 4).
3. Check for an open or a short in any corresponding circuit that indicated a No. 1 below output driver. If open or short does not exist, go to step 8). If open or short exists, repair as necessary and go to step 10).
4. Using scan tool, command output being checked while watching corresponding position for that circuit. If that circuits position does not change to a No. 1, go to next step. If that circuits position changes to a No. 1, go to step 7).
5. If component or function does not operate when commanded, go to next step. If component or function operates when commanded, go to step 10).
6. Make necessary repairs to component or component circuit as necessary and go to step 10).
7. Repair short to voltage in corresponding circuit and go to step 10).
8. Disconnect appropriate component harness connector. If No. 1 is still displayed below that component's numbered position, go to next step. If No. 1 is not still displayed below that components numbered position, go to step 6).
9. Replace PCM and go to next step.
10. Operate vehicle under condition under which original symptom was noted. If system does not operate properly, go to step 2).

Ground Circuits

1. Using an ohmmeter, check for continuity to ground at PCM ground terminals. See «POWERTRAIN CONTROL MODULE (PCM) CONNECTOR I.D.»(/chevrolet/malibu/v-1996-2000/remont/testing-diagnostics/#engine-control-system-testing-engine-component-testing-24l) table. Resistance should be zero ohms. If not, repair open to ground.
2. Using a voltmeter, connect negative lead of voltmeter to a good ground. Backprobe positive lead of voltmeter to each ground terminal. With vehicle running, voltmeter should indicate less than one volt. If voltmeter reading is more than one volt, check for open, short to voltage, corrosion or loose connection on ground circuit.

Power Circuits

1. Using a voltmeter, check for battery voltage between PCM continuous power terminal(s) and ground. See «POWERTRAIN CONTROL MODULE (PCM) CONNECTOR I.D.»(/chevrolet/malibu/v-1996-2000/remont/testing-diagnostics/#engine-control-system-testing-engine-component-testing-24l) table. If battery voltage is not present, check for blown fuse or open fusible link. If okay, check for open in wire between PCM terminal and power source.
2. Turn ignition switch to RUN position. Using a voltmeter, check for battery voltage between PCM ignition power terminals and ground. If battery voltage is not present, check IGN fuse. If fuse is okay, check for an open in wire between battery and ignition switch, and between ignition switch and PCM terminal. If okay, check for a defective ignition switch.
3. Connect voltmeter between ground and PCM starter (crank) signal terminal. On vehicles with manual transmission/transaxle, depress clutch pedal. On vehicles with automatic transmission/transaxle, position gear shift 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 terminal. If fuse or fusible link is okay, check for an open in wire between ignition switch and PCM terminal, or check for a defective ignition switch.

PCM Harness Resistance

Turn ignition switch to LOCK position. Disconnect PCM and appropriate component harness connectors. Check for open or short circuits between PCM harness connector terminal and component harness connector terminal. See POWERTRAIN CONTROL MODULE (PCM) CONNECTOR I.D. table. See WIRING DIAGRAMS - 2.4L article. If harness is open or shorted, repair as necessary.

POWERTRAIN CONTROL MODULE (PCM) CONNECTOR I.D. (1)

Scheme 3

DIAGNOSTIC TROUBLE CODES

TROUBLE CODE DEFINITION

ENGINE SENSORS & SWITCHES

Note. For additional sensor testing specifications, see SENSOR RANGE CHARTS - 2.4L article.

Manufacturer does not provide many individual system and component testing. For sensor and switch testing not listed, perform related DTC testing procedure. See DIAGNOSTIC TROUBLE CODES in TESTS W/CODES - 2.4L article.

Engine Coolant Level Sensor

1. If powertrain OBD system check has been performed, go to next step. If powertrain OBD system check has not been performed, perform powertrain OBD system check. See POWERTRAIN OBD SYSTEM CHECK in TESTS W/CODES - 2.4L article.
2. Retrieve DTCs. If DTCs do not exist, go to next step. If DTCs exist, perform appropriate DTC test. See TESTS W/CODES - 2.4L article.
3. Turn ignition switch to RUN position. If coolant level light illuminates for approximately 3 seconds then turn off, go to next step. If coolant level light does not illuminate for approximately 3 seconds then turn off, go to step 5).
4. Drain coolant from surge tank. Ensure ignition switch is in RUN position. If coolant level light does not illuminate, go to step 6). If coolant level light illuminates, go to step 20).
5. Check coolant level in surge tank. If coolant level is not okay, go to step 8). If coolant level is okay, go to step 7).
6. Disconnect coolant level sensor harness connector. Using a test light connected to battery voltage, probe coolant level ground circuit (Black/White wire) at coolant level sensor harness connector. If test light illuminates, go to step 9). If test light does not illuminate, go to step 10).
7. Disconnect coolant level sensor harness connector. Ensure ignition switch is in RUN position. If coolant level light does not illuminate, go to step 17). If coolant level light illuminates, go to step 11).
8. Fill surge tank and go to step 2).
9. Measure voltage at coolant level sensor signal circuit (Yellow/Black wire) at coolant level sensor harness connector. If battery voltage exists, go to step 12). If battery voltage does not exist, go to step 13).
10. Repair poor connection at or open in coolant level sensor ground circuit. After repair is complete, go to step 20).
11. Using a test light connected to battery voltage, probe coolant level sensor signal circuit (Yellow/Black wire) at cool level sensor harness connector. If test light illuminates, go to step 14). If test light does not illuminate, go to step 15).
12. Using a test light connected to ground, probe coolant level sensor signal circuit (Yellow/Black wire) at coolant level sensor harness connector. If test light illuminates, go to step 16). If test light does not illuminate, go to step 17).
13. Check for poor connection at or open in coolant level sensor signal circuit. If problem does not exist, go to step 19). If problem exists, repair as necessary and go to step 20).
14. Check for short to ground in coolant level sensor signal circuit. If problem does not exist, go to step 19). If problem exists, repair as necessary and go to step 20).
15. Connect scan tool to data link connector. Observe coolant level on scan tool. If LOW is displayed, go to step 19). If LOW is not displayed, go to step 18).
16. Check for short to voltage in coolant level sensor signal circuit. If problem does not exist, go to step 19). If problem exists, repair as necessary and go to step 20).
17. Replace coolant level sensor and go to step 20).
18. Replace or repair instrument cluster as necessary. After repairs are complete, go to step 20).
19. Replace PCM and go to next step.
20. Operate vehicle under conditions which original symptom was noted. If system operates properly, system is okay at this time. If system does not operate properly, go to step 2).

Manifold Absolute Pressure (MAP) Sensor Diagnosis

1. If powertrain OBD system check has been performed, go to next step. If powertrain OBD system check has not been performed, perform powertrain OBD system check. See POWERTRAIN OBD SYSTEM CHECK in TESTS W/CODES - 2.4L article.
2. Connect scan tool to data link connector. Retrieve DTCs. If no MAP sensor related DTCs exist, go to next step. If any MAP sensor related DTCs exist, perform appropriate DTC test. See TESTS W/CODES - 2.4L article.
3. Turn ignition switch to RUN position. Compare map sensor reading with that of a known-good vehicle. If voltage readings are within 0.4 volt of each other, go to next step. If voltage readings are not within 0.4 volt of each other, go to step 5).
4. Disconnect and plug vacuum source to MAP sensor. Connect vacuum pump to vacuum source port on MAP sensor. Apply 10 in. Hg of vacuum to map sensor while observing MAP sensor reading on scan tool. Subtract this reading from the reading obtained in step 3). If difference is greater than 1.5 volts, go to step 6). If difference is not greater than 1.5 volts, go to step 7).
5. Replace MAP sensor and go to step 9).
6. Check MAP sensor vacuum source for leakage or restriction and that vacuum source only supplies MAP sensor. If problem exists, go to step 8). If problem does not exist, go to step 9).
7. Check for poor connection at MAP sensor. If poor connection does not exist, go to step 2). If poor connection exists, repair as necessary and go to step 9).
8. Repair MAP sensor vacuum source as necessary and go to next step.
9. Operate vehicle under conditions which original symptom was noted. If system does not operate properly, go to step 2). If system operates properly, system is okay at this time.

MOTORS, RELAYS & SOLENOIDS

Manufacturer does not provide many individual system and component testing. For motor, relay and solenoid testing not listed, perform related DTC testing procedure. See DIAGNOSTIC TROUBLE CODES under COMPUTERIZED ENGINE CONTROLS. See TESTS W/CODES - 2.4L article.

Idle Air Control (IAC) Motor

See IDLE CONTROL SYSTEM.

A/C Clutch Relay

See A/C-HEATER SYSTEM article in AIR CONDITIONING & HEAT section.

Fuel Pump Relay

See BASIC TESTING - 2.4L article.

SOLENOIDS

All PCM-controlled solenoids should have at least 20 ohms of resistance when checked with positive ohmmeter lead connected to power supply terminal of solenoid and negative ohmmeter lead connected to ground terminal of solenoid. Some solenoids are equipped with internal diodes. On these solenoids, resistance values will differ if ohmmeter test leads are reversed.

FUEL SYSTEM

Note. For fuel system pressure testing, see BASIC TESTING - 2.4L article.

Manufacturer does not provide many individual system and component testing. For fuel system testing not listed, perform related DTC testing procedure. See DIAGNOSTIC TROUBLE CODES in TESTS W/CODES - 2.4L article.

Note. Retrieve DTCs and perform appropriate DTC test before performing FUEL INJECTOR CIRCUIT DIAGNOSIS. See TESTS W/CODES - 2.4L article. Also ensure all mechanical and ignition coil/module circuit malfunctions are repairs before performing FUEL INJECTOR CIRCUIT DIAGNOSIS.

Fuel Injector Balance Test

1. If powertrain OBD system check has been performed, go to next step. If powertrain OBD system check has not been performed, perform powertrain OBD system check. See POWERTRAIN OBD SYSTEM CHECK in TESTS W/CODES - 2.4L article.
2. If fuel injector coil test has been performed, go to next step. If fuel injector coil test has not been performed, perform fuel injector coil test. See INJECTOR COIL TEST - ECT BETWEEN 50-95°F.
3. If engine coolant temperature is below 201°F (94°C), go to step 5). If engine coolant temperature is above 201°F (94°C), go to next step.
4. Allow engine to cool until coolant temperature is below 210°F (94°C), then go to next step.
5. Install fuel pressure gauge. Turn ignition switch to RUN position then to LOCK position. Bleed air from fuel pressure gauge. Using scan tool, energize fuel pump. If fuel pressure reading is 41-47 psi (2.9-3.3 kg/cm 2 ), go to next step. If fuel pressure reading is not within specification, perform fuel system diagnosis. See BASIC TESTING - 2.4L article.
6. Turn fuel pump off. Observe fuel pressure gauge. If fuel pressure remains constant, go to next step. If fuel system does not remain constant, perform fuel system diagnosis. See BASIC TESTING - 2.4L article. NOTE: Perform step 7) on each injector.
7. Disconnect fuel injectors harness connector. Using appropriate fuel injector adapter, connect Fuel Injector Tester (J-39021) to fuel injector. Connect fuel injector tester power leads to appropriate battery terminals. Set amperage supply selector switch on fuel injector tester to Balance Test 2.5-amp position. Turn ignition switch to RUN position then to LOCK position. Record fuel pressure reading (first reading). Energize injector by depressing PUSH TO START TEST button on injector tester and hold until fuel pressure gauge stabilizes. Record fuel pressure reading (second reading). Subtract first reading from second reading (this result is pressure drop value). Add pressure drop value for each injector together and divide total by total number of injectors. If any injector's drop value is greater or less than average drop value by 1.5 psi, replace faulty injector(s) as necessary. If no injector's drop value is greater or less than average drop value by 1.5 psi, injector balance test is okay at this time.

Injector Coil Test ECT Between 50-95°F

1. If powertrain OBD system check has been performed, go to next step. If powertrain OBD system check has not been performed, perform powertrain OBD system check. See POWERTRAIN OBD SYSTEM CHECK in TESTS W/CODES - 2.4L article.
2. Connect scan tool to data link connector. Using scan tool, check engine coolant temperature. If 50-95°F (10-35°C) is displayed, go to next step. If 50-95°F (10-35°C) is not displayed, perform INJECTOR COIL TEST - ECT NOT BETWEEN 50-95°F test. NOTE: Perform step 3) on each injector.
3. Turn ignition switch to LOCK position. Relieve fuel pressure. Disconnect fuel injector harness connectors. Using appropriate fuel injector adapter, connect Fuel Injector Tester (J-39021) to fuel injector. Connect fuel injector tester power leads to appropriate battery terminals. Set amperage supply selector switch on fuel injector tester to Coil Test 0.5-amp position. connect DVOM to injector tester. Depress PUSH TO START TEST button. Record lowest voltage reading within first second of test. If any injector has erratic voltage reading or reading not 4.7-5.8 volts, go to next step. If no injector has erratic voltage reading or reading not 4.7-5.8 volts, perform injector balance test. See FUEL INJECTOR BALANCE TEST.
4. Replace faulty injector(s) and perform injector balance test. See FUEL INJECTOR BALANCE TEST.

Injector Coil Test ECT Not Between 50-95°F

1. If powertrain OBD system check has been performed, go to next step. If powertrain OBD system check has not been performed, perform powertrain OBD system check. See POWERTRAIN OBD SYSTEM CHECK in TESTS W/CODES - 2.4L article.
2. Connect scan tool to data link connector. Using scan tool, check engine coolant temperature. If 50-95°F (10-35°C) is not displayed, go to next step. If 50-95°F (10-35°C) is displayed, perform INJECTOR COIL TEST - ECT BETWEEN 50-95°F test. NOTE: Perform step 3) on each injector.
3. Turn ignition switch to LOCK position. Relieve fuel pressure. Disconnect fuel injector harness connectors. Using fuel injector adapter, connect Fuel Injector Tester (J-39021) to fuel injector. Connect fuel injector tester power leads to appropriate battery terminals. Set amperage supply selector switch on fuel injector tester to Coil Test 0.5-amp position. Connect DVOM to injector tester. Depress PUSH TO START TEST button. Record highest voltage reading other than those greater than 9.5 volts. Subtract any other voltage reading observed from highest voltage reading. If difference is greater than 0.7 volt, go to next step. If difference is not greater than 0.7 volt, perform injector balance test. See FUEL INJECTOR BALANCE TEST.
4. Replace any injector(s) that had any of the following results: initial reading greater than 9.5 volts, erratic reading or difference is greater than 0.6 volt. After repairs are complete, perform injector balance test. See FUEL INJECTOR BALANCE TEST.

IDLE CONTROL SYSTEM

Note. Manufacturer does not provide system testing for 2.4L. For idle control system testing not listed, perform related DTC testing procedure. See DIAGNOSTIC TROUBLE CODES in TESTS W/CODES - 2.4L article.

IGNITION SYSTEM

Note. For basic ignition system checks, see BASIC TESTING - 2.4L article.

For ignition system testing not listed, perform related DTC testing procedure. See DIAGNOSTIC TROUBLE CODES in TESTS W/CODES - 2.4L article.

EMISSION SYSTEMS & SUB-SYSTEMS

Note. For emission and sub-system testing not listed, perform related DTC testing procedure. See DIAGNOSTIC TROUBLE CODES in TESTS W/CODES - 2.4L article.

EVAP CONTROL SYSTEM DIAGNOSIS

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

1. If powertrain OBD system check has been performed, go to next step. If powertrain OBD system check has not been performed, perform powertrain OBD system check. See POWERTRAIN OBD SYSTEM CHECK in TESTS W/CODES - 2.4L article.
2. Connect scan tool to data link connector. Turn ignition switch to RUN position. Retrieve DTCs. If no DTCs exist, go to next step. If any DTCs exist, perform appropriate DTC test. See TESTS W/CODES - 2.4L article.
3. Using scan tool, command EVAP canister purge valve and EVAP canister vent valve on and off. If both purge valve and vent valve click when toggled on and off, go to next step. If either purge valve or vent valve do not click when toggled on and off, perform PCM output diagnosis. See PCM OUTPUT DIAGNOSIS under COMPUTERIZED ENGINE CONTROLS.
4. Turn ignition switch to LOCK position. Remove fuel filler cap. Turn ignition switch to RUN position. Observe fuel tank pressure on scan tool. If zero in. Hg exists, go to next step. If zero in. Hg does not exist, perform DTC P0452 or DTC P0453 test. See TESTS W/CODES - 2.4L article.
5. Install fuel filler cap. Connect Enhanced Pressure Purge Diagnosis Tester (J-41413) to EVAP service port. Using scan tool, command EVAP vent valve on. Pressurize EVAP system to .47 in. Hg. Observe fuel tank pressure on scan tool. If .47 in. Hg is displayed, go to next step. If .47 in. Hg is not displayed, perform DTC P0452 or DTC P0453 test. See TESTS W/CODES - 2.4L article.
6. Observe EVAP system pressure on diagnostic tester. Using scan tool, command EVAP canister vent valve off. If EVAP system pressure decreases to zero in. Hg within 5 seconds, go to next step. If EVAP system pressure does not decrease to zero in. Hg within 5 seconds, perform DTC P0446 test. See TESTS W/CODES - 2.4L article.
7. Start engine. Remove gas cap. Using scan tool seal EVAP system. Install fuel filler cap. Increase engine speed to 1500 RPM. Observe fuel tank pressure on scan tool. If fuel tank pressure does not decrease, go to next step. If fuel tank pressure is decreasing, perform DTC P1441 test. See TESTS W/CODES - 2.4L article.
8. Using scan tool, command EVAP canister vent valve and EVAP canister purge valve on. Increase engine speed to 1500 RPM. Observe fuel tank pressure on scan tool. If fuel tank pressure is decreasing, system is okay at this time. If fuel tank pressure does not decrease, perform DTC P0440 test. See TESTS W/CODES - 2.4L article.

AIR Pump (Belt-Driven)

Accelerate engine to approximately 1500 RPM and observe airflow from hoses. If airflow increases as engine is accelerated, pump is working properly. If airflow does not increase, check hoses, pump belt tension, leaky valves or defective air injection pump.

Check Valve

Detach check valve and blow through valve in direction of check valve flow (to cylinder head). Attempt to suck air back. Replace valve if airflow is allowed against the direction of flow.

EXHAUST GAS RECIRCULATION

Manufacturer does not provide many individual system and component testing. For EGR system testing not listed, perform related DTC testing procedure. See DIAGNOSTIC TROUBLE CODES in TESTS W/CODES - 2.4L article.

Exhaust System Check

1. If powertrain OBD system check has been performed, go to next step. If powertrain OBD system check has not been performed, perform powertrain OBD system check. See POWERTRAIN OBD SYSTEM CHECK in TESTS W/CODES - 2.4L article.
2. Remove heated oxygen sensor. Install exhaust backpressure tester in place of oxygen sensor. Start engine and let idle. If pressure reading is not .5 psi or greater, go to next step. If pressure reading is .5 psi or greater, go to step 4).
3. Increase engine speed to 3000 RPM. If pressure reading is greater than .75 psi or greater, go to next step. If pressure reading is not greater than .75 psi or greater, go to step 6).
4. Check exhaust system for crushed pipe, internal muffler damage or heat distress. If problem does not exist, go to next step. If problem exists, repair as necessary and go to step 6).
5. Replace catalytic converter and go to next step.
6. Operate vehicle within conditions under which original symptom was noted. If system operate properly, system is okay at this time. If system does not operate properly, go to step 2).

Required Service

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

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

A leaking PCV valve or hose could cause

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

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

Checking PCV Valve Function

1. Remove PCV valve from rocker cover. Run engine at idle. Place thumb over open end of valve to check for vacuum. If there is no vacuum at valve, check for obstruction in manifold port, hoses or PCV valve. Repair or replace as necessary.
2. Turn engine off. Remove PCV valve. Shake valve and listen for rattle of check valve inside. 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 if necessary.
4. An 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.

TRANSMISSION

Note. Computerized transmission controls are also covered in greater detail in TRANSMISSION SERVICING - A/T article in AUTOMATIC TRANS SERVICE section section manual for domestic vehicles. For component circuit identification, see wiring diagram in WIRING DIAGRAMS - 2.4L article.

Converter Clutch Solenoid

Disconnect harness connector to Torque Converter Clutch (TCC) solenoid. Measure resistance between appropriate TCC solenoid terminals. Solenoid resistance should be greater than 20 ohms.

Note. Some solenoids may have an internal pressure switch in series with the solenoid winding and will not show continuity until that pressure switch is applied by transmission hydraulic pressure.

Converter Lock-Up Signal At Transmission

1. Warm engine to operating temperature. Raise vehicle and support drive wheels. Support suspension where necessary to prevent damage to drive axles.
2. Disconnect converter clutch connector at transmission. Connect a test light across appropriate converter clutch harness terminals. Start engine and place transmission in Drive. Accelerate vehicle to 45 MPH and note test light.
3. If test light is off, check solenoid power supply wire of harness for open or short to ground. Check ground circuit for open between harness connector and PCM. If harness is okay, see CONVERTER LOCK-UP SIGNAL FROM PCM.

Converter Lock-Up Signal From PCM

1. Warm engine to operating temperature. Raise vehicle and support drive wheels. Support suspension where necessary to prevent damage to drive axles.
2. Connect a test light to battery voltage. Touch TCC control driver terminal with test light. Accelerate vehicle to 45 MPH and note test light. If test light does not illuminate, problem is a faulty PCM connector or PCM.

PCM CONTROLLED GENERATOR

1. If powertrain OBD system check has been performed, go to next step. If powertrain OBD system check has not been performed, perform powertrain OBD system check. See POWERTRAIN OBD SYSTEM CHECK in TESTS W/CODES - 2.4L article.
2. Turn ignition switch to RUN position. If charging light illuminates, go to next step. If charging light does not illuminate, go to step 4).
3. Start engine. If charging light does not go out, go to step 5). If charging light goes out, go to step 21).
4. Turn ignition switch to LOCK position. Disconnect generator harness connectors. Turn ignition switch to RUN position. If charging light illuminates, go to step 6). If charging light does not illuminate, go to step 7).
5. Turn ignition switch to LOCK position. Connect scan tool to data link connector. Turn ignition switch to RUN position. Ensure all accessories are off. Observe generator voltage on scan tool. If battery voltage is displayed, go to step 8). If less than battery voltage is displayed, go to step 9).
6. Using a test light connected to ground, probe charging light signal circuit at generator harness connector. If test light illuminates, go to step 10). If test light does not illuminate, go to step 11).
7. Replace or repair instrument cluster and/or charging light bulb as necessary. After repairs are complete, go to step 21).
8. Using scan tool, check GEN F valve. If 5 percent is displayed, go to step 7). If 5 percent is not displayed, go to step 12).
9. Turn ignition switch to LOCK position. Disconnect generator harness connectors. Turn ignition switch to RUN position. Using a test light connected to battery voltage, probe charging light signal circuit at generator harness connector. If test light illuminates, go to step 13). If test light does not illuminate, go to step 14).
10. Locate and repair short to ground in charging light control signal circuit and go to step 21).
11. Replace generator and go to step 21).
12. Turn ignition switch to LOCK position. Disconnect generator harness connectors. Turn ignition switch to RUN position. Using a test light connected to battery voltage, probe generator field circuit at generator harness connector. If test light illuminates, go to step 15). If test light does not illuminate, go to step 16).
13. Locate and repair short to ground in field circuit and go to step 21).
14. Measure voltage at charging light signal circuit at generator harness connector. If 4.5 volts or greater exists, go to step 17). If 4.5 volts or greater does not exist, go to step 18).
15. Locate and repair short to ground in field circuit. After repairs are complete, go to step 21).
16. Locate and repair poor connection and/or open in field circuit. After repairs are complete, go to step 21).
17. Measure voltage at battery voltage supply circuit at generator harness connector. If battery voltage exist, go to step 11). If battery voltage does not exist, go to step 19).
18. Check for poor connection and/or open in battery voltage supply circuit. If poor connection and/or open does not exist, go to step 20). If poor connection and/or open exists, repair as necessary and go to step 21).
19. Locate and repair poor connection and/or open in battery voltage supply circuit. After repairs are complete, go to step 21).
20. Replace PCM and go to next step.
21. Operate vehicle under condition under which original symptom was noted. If system does not operate properly, go to step 2).

A/C COMPRESSOR CLUTCH CONTROLS

Note. For A/C clutch circuit testing, see A/C-HEATER SYSTEM article in the AIR CONDITIONING & HEAT section. See wiring diagram in WIRING DIAGRAMS - 2.4L article for terminal and wire color identification.

To provide improved idle quality, improved Wide Open Throttle (WOT) performance and A/C system protection, the compressor clutch is controlled by PCM.

For proper control of cooling fans, compressor clutch and Idle Air Control (IAC) valve, a refrigerant pressure sensor is used. PCM uses signals provided by sensor to monitor high and low side refrigerant pressures. If PCM detects a fault in refrigerant pressure circuit, compressor clutch will be disabled.

The A/C clutch relay is controlled by PCM. This allows PCM to raise idle speed before engaging compressor clutch, or disable compressor clutch during WOT, high engine RPM, high power steering loads and hot engine restarts. PCM also disables compressor clutch if coolant temperature becomes excessive. To locate A/C clutch relay, see A/C CLUTCH RELAY LOCATION table.

A/C CLUTCH RELAY LOCATION

Note. To help save diagnostic time, check for blown fuses or fusible links before proceeding with any testing. If fuses are blown, locate and repair short circuit before replacing fuses. Ensure all related relay and wire harness connections are clean and tight. Repair as necessary.

ELECTRIC COOLING FAN CONTROL

Note. For electric cooling fan circuit testing, see AIR CONDITIONING & HEAT section. See wiring diagram in WIRING DIAGRAMS - 2.4L article for terminal and wire color identification.

All FWD and some RWD vehicles use an electric cooling fan. The electric cooling fan is used for radiator and A/C condenser cooling. Cooling fan operates when A/C is on and when engine coolant temperature exceeds a specific value. One or more cooling fan relays may be used. For cooling fan relay location, see COOLING FAN RELAY LOCATION table.

COOLING FAN RELAY LOCATION

To help save diagnostic time, ALWAYS check for blown fuses or fusible links before proceeding with any testing. If fuses are blown, locate and repair short circuit before replacing fuses. Ensure all related relay and wire harness connections are clean and tight. Repair as necessary. For component location and terminal and wire color identification, see wiring diagram in WIRING DIAGRAMS - 2.4L article.

COMPONENT LOCATIONS

Note. Component location illustrations are not available for Malibu.

COMPONENT LOCATIONS (VIN T)

See also:
• AUTO TRANS DIAGNOSIS - 4T40-E
• POWERTRAIN CONTROL MODULE (PCM) CONNECTOR I.D.