Engine Controls - Basic Diagnostic Procedures - 2.4l Chevrolet Malibu V

INTRODUCTION

The following diagnostic steps will help prevent overlooking a simple problem. This is also where to begin diagnosis for a no-start condition.

The first step in diagnosing any driveability problem is verifying the customer's complaint with a test drive under the conditions during which the problem reportedly occurred.

Before entering self-diagnostics, perform a careful and complete visual inspection. Most engine control 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.

Note. Unless otherwise instructed in test procedures, perform all voltage tests using a Digital Volt-Ohmmeter (DVOM) with a minimum 10-megohm input impedance.

VISUAL INSPECTION

Visually inspect all electrical wiring, looking for chafed, stretched, cut or pinched wiring. Ensure electrical connectors fit tightly and are not corroded. Ensure vacuum hoses are properly routed and not pinched or cut. If necessary, see VACUUM DIAGRAMS - 2.4L article to verify routing and connections. Inspect air induction system for possible vacuum leaks.

Compression

Check engine mechanical condition with a compression gauge, vacuum gauge, or an engine analyzer. See engine analyzer manual for specific instructions. For compression specifications, see SPECIFICATIONS - 2.4L article.

Exhaust System Backpressure

Before replacing any components, check exhaust system for restrictions. Use a vacuum gauge or a low-pressure (0-5 psi) gauge to check exhaust system.

If a vacuum gauge is used, connect vacuum gauge hose to intake manifold vacuum port and start engine. Observe vacuum gauge. Partially open throttle and hold steady. If vacuum gauge reading slowly drops after stabilizing, exhaust system should be checked for a restriction. If using a low pressure gauge, connect gauge in one of the following manners

1. Check At AIR Check Valve Remove AIR check valve. Install backpressure tester in place of AIR check valve.
2. Check At Oxygen Sensor Remove oxygen sensor. Install backpressure tester in place of oxygen sensor. After test is completed, coat oxygen sensor threads with anti-seize compound before installation.

Diagnosis

1. Start engine and bring to operating temperature. Increase engine speed to 2000-2500 RPM and note gauge. If reading exceeds 1.25 psi (.09 kg/cm 2 ), exhaust system is restricted.
2. Check exhaust system for collapsed pipe, heat distress and possible internal muffler failure. If none of these conditions exist, check for restricted catalytic converter. Replace as required.

NO START DIAGNOSIS

Note. Some vehicles are equipped with anti-theft systems (VATS or PASS-Key(R)) 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.

Note. For terminal and circuit identification, see WIRING DIAGRAMS - 2.4L article.

Definition

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

NO START - ENGINE CRANKS OKAY (WITH IDI)

Note. Before performing following tests, check battery condition, engine cranking speed and for adequate fuel in tank.

General Inspection

1. Ensure proper starting procedure is being used. Visually check vacuum hoses for splits, kinks and proper connections, as shown on Vehicle Emission Control Information label. Check ignition wires for cracking, hardness and proper connections at both coil pack and spark plugs.
2. Remove spark plugs. Check and replace as necessary. In very cold temperatures, ensure oil is proper viscosity and not contaminated with gasoline.

Ignition System

1. Perform On-Board Diagnostic (OBD) System Check. See ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK in TESTS W/CODES - 2.4L article. After performing OBD system check, go to next step.
2. Check for Diagnostic Trouble Codes (DTCs). If DTC P0335, P0601, P0602 or P1629 is present, diagnose DTC(s). See TESTS W/CODES - 2.4L article. If DTC(s) is not present, go to next step.
3. Check PCM ground connection on engine block. If ground connection is okay, go to next step. If ground connection is faulty, go to step 5).
4. Check fuel pump, injector ignition feed and ignition feed fuses. If fuses are okay, go to step 6). If fuses are defective, go to step 7).
5. Repair PCM ground connection. After repairs, go to step 36).
6. Check fuel level in tank and add fuel if necessary. If fuel level is okay, go to step 8). If fuel level was low and fuel needed to be added, go to step 36).
7. Check for short to ground in fuel pump and injector ignition feed circuit. Repair as necessary. Replace defective fuse. After repairs, go to step 36).
8. Install scan tool. Turn ignition on with engine off. Ensure throttle is closed. Scan TP sensor. TP sensor value should be less than one volt. If TP sensor value is as specified, go to next step. If TP sensor value is not as specified, diagnose problem using DTC P0121. See TESTS W/CODES - 2.4L article.
9. Using scan tool, monitor Engine Coolant Temperature (ECT) sensor and Intake Air Temperature (IAT) sensor values. Both values should be about the same. If values are the same, go to next step. If values are not the same, diagnose problem using DTC P0117 or P0118. See TESTS W/CODES - 2.4L article.
10. Check MAP sensor value with ignition on and engine cranking. If MAP sensor value is greater than 4 volts, and then changes while cranking engine, go to next step. If MAP sensor value is less than 4 volts and does not change while cranking engine, go to step 12).
11. Using scan tool, check Crankshaft Position (CKP) sensor activity while cranking engine. If CKP ACTIVITY COUNTER increments while cranking, go to step 26). If CKP ACTIVITY COUNTER does not increment, go to step 14).
12. If serial data was lost while cranking engine, go to next step. If serial data was not lost while cranking engine, diagnose MAP sensor. See SYSTEM/COMPONENT TESTS - 2.4L article.
13. Repair voltage loss to PCM from ignition switch. After repairs, go to step 36).
14. Turn ignition off. Disconnect 11-pin Ignition Control Module (ICM) connector. Turn ignition on with engine off. Connect DVOM between ICM ground and ignition feed terminals. See WIRING DIAGRAMS - 2.4L article. Battery voltage should be present. If battery voltage is present, go to next step. If battery voltage is not present, go to step 16).
15. Connect DVOM between ICM connector CKP sensor ground terminal and CKP sensor signal terminal. See WIRING DIAGRAMS - 2.4L article. Check combined CKP sensor and resistance. Resistance should be 500-900 ohms. If resistance is as specified, go to step 18). If resistance is not as specified, go to step 17).
16. Repair open in ground circuit or ignition feed circuit to ICM. After repairs, go to step 36).
17. Remove CKP sensor. Ensure CKP sensor is still magnetized and terminals are not damaged. Using DVOM, check CKP sensor resistance. Resistance should be 500-900 ohms. If resistance is as specified, go to step 20). If resistance is not as specified, go to step 21).
18. Set DVOM to AC scale. Connect DVOM between ICM connector CKP sensor ground terminal and CKP sensor signal terminal. See WIRING DIAGRAMS - 2.4L article. Crank engine. Voltage reading should be greater than 200 millivolts. If voltage reading is as specified, go to next step. If voltage reading is not as specified, go to step 17).
19. Using a test light connected to ICM connector 7X reference signal terminal, touch battery negative terminal, and then battery positive terminal. See WIRING DIAGRAMS - 2.4L article. Monitor CKP ACTIVITY COUNTER increment on scan tool. If CKP ACTIVITY COUNTER increments as test light is touched to battery positive, go to step 22). If CKP ACTIVITY COUNTER does not increment, go to step 23).
20. Repair poor connection, open or short in CKP sensor. After repairs, go to step 36).
21. Replace CKP sensor. After replacing CKP sensor, go to step 36).
22. Inspect ICM connector. Check for clean and tight connections. Repair as necessary. After repairs, go to step 36). If connector is okay, go to step 24).
23. Check CKP activity (7X reference) circuit for an open or short. Repair circuit as necessary. After repairs, go to step 36). If circuit is okay, go to step 25).
24. Replace ICM. After replacing ICM, go to step 36).
25. Turn ignition off. Check for poor connection at PCM. Repair as necessary. If connection is okay, replace PCM. Perform PCM relearn procedures. After replacing PCM, go to step 36).
26. Disconnect all injectors. Install injector test light on injector No. 1 connector. Crank engine and observe injector test light. If test light flashes, go to next step. If test light does not flash, go to step 30).
27. Remove ignition coil and ignition control module assembly. Install Spark Plug Jumper (J-36012) between coil and ignition control module. Remove spark plug boot from companion cylinder of ignition coil housing and install jumper wire from spark plug boot connector of ignition housing to ground (cylinders No. 1-4 and 2-3). Using Spark Tester (J-26792), check for spark on all 4 wires (one at a time). If spark jumps spark tester on all 4 wires, go to next step. If spark does not jump on any or all of the 4 wires, go to step 31).
28. Install fuel pressure gauge. Turn ignition on with engine off, for 2 seconds. Fuel pressure should be 41-47 psi (2.9-3.3 kg/cm 2 ). If fuel pressure is as specified, go to next step. If fuel pressure is not present, go to FUEL SYSTEM ELECTRICAL CIRCUIT. If fuel pressure is present, but not as specified, diagnose fuel system. See «BASIC FUEL SYSTEM CHECKS»(/chevrolet/malibu/v-1996-2000/remont/testing-diagnostics/#engine-controls-basic-diagnostic-procedures-24l__basic-fuel-system-checks) .
29. Check for fouled spark plugs. Replace as necessary. If spark plugs were fouled, go to step 36). If spark plugs were okay, check for water in fuel system. Check for basic engine problem (low compression). Ensure spark plugs are of resistor type. Check fuel pump operation with scan tool.
30. Repair open in fuel pump and injector ignition feed circuit. After repairs, go to step 36). CAUTION: DO NOT leave jumper wire connected to PCM connector ignition control circuit for more than 5 seconds at a time as ignition coil and/or Ignition Control Module (ICM) may be damaged.
31. Turn ignition off. Disconnect Powertrain Control Module (PCM) connectors. Turn ignition on. Connect a fused jumper wire to battery voltage and momentarily touch affected ignition control circuit with fused jumper wire. A spark should jump across spark tester. If a spark jumps across tester, go to step 25). If a spark does not jump across tester, go to next step.
32. Turn ignition off. Disconnect jumper wires and remove ignition coil housing. Reconnect PCM connectors. Disconnect ignition coil connector at ICM. Connect test light between battery voltage and ICM control terminal for ignition coil(s) that did not spark. Crank engine and observe test light. Test light should flash as engine is cranked. If test light flashed, go to next step. If test does not flash while cranking, go to step 35).
33. Check for faulty ignition coil connector or open in ignition coil. Repair as necessary. After repairs, go to step 36). If connector and are okay, go to step 34).
34. Replace ignition coil that did not produce a spark. After repairs, go to step 36).
35. Check for an open or short in ignition control circuit. Repair as necessary. After repairs, go to next step. If circuit is okay, go to step 22).
36. Using scan tool, clear DTC(s). Attempt to start engine. If engine starts and continues to run, go to next step. If engine does not start, or starts but dies, go to step 2).
37. Warm engine to operating temperature. Check for DTC(s). If DTC(s) is present, diagnose DTC(s). See TESTS W/CODES - 2.4L article. If DTC(s) is not present, system is okay.

Fuel System Electrical Circuit

1. Perform On-Board Diagnostic (OBD) System Check. See ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK in TESTS W/CODES - 2.4L article. After performing OBD system check, go to next step.
2. Check fuel pump relay fuse. If fuse is okay, go to next step. If fuse is faulty, go to step 20).
3. Install scan tool. Turn ignition on. Using scan tool, command fuel pump on. Fuel pump should operate for about 2 seconds. If fuel pump operates as specified, diagnose fuel system. See «BASIC FUEL SYSTEM CHECKS»(/chevrolet/malibu/v-1996-2000/remont/testing-diagnostics/#engine-controls-basic-diagnostic-procedures-24l__basic-fuel-system-checks) . If fuel pump does not operate, go to next step.
4. Remove fuel pump relay. Using a fused jumper wire, jumper fuel pump relay feed terminal and fuel pump relay ignition feed terminal. See WIRING DIAGRAMS - 2.4L article. If fuel pump operates, go to next step. If fuel pump does not operate, go to step 6).
5. Using a test light connected to ground, probe fuel pump relay control terminal. See WIRING DIAGRAMS - 2.4L article. Using scan tool, command fuel pump on. If test light illuminates, go to step 7). If test light does not illuminate, go to step 8).
6. Using a test light connected to ground, probe fuel pump relay ignition feed terminal. See WIRING DIAGRAMS - 2.4L article. If test light illuminates, go to step 9). If test light does not illuminate, go to step 10).
7. Using a test light connected to battery voltage, probe fuel pump relay ground terminal. See WIRING DIAGRAMS - 2.4L article. If test light illuminates, go to step 11). If test light does not illuminate, go to step 12).
8. Check for an open or short to ground in fuel pump relay control circuit. Repair as necessary. After repairs, go to step 25). If circuit is okay, go to step 13).
9. Reinstall fuel pump relay. Disconnect fuel pump connector at fuel pump. Using a test light connected to ground, probe fuel pump connector feed terminal (body side). Using scan tool, command fuel pump on. If test light illuminates, go to step 14). If test light does not illuminate, go to step 15).
10. Repair open in ignition feed circuit to fuel pump relay. After repairs, go to step 25).
11. Replace fuel pump relay. After replacing fuel pump relay, go to step 25).
12. Repair open in ground circuit to fuel pump relay. After repairs, go to step 25).
13. Check connections and terminals to PCM. Repair as necessary. After repairs, go to step 25). If connections and terminals are okay, go to step 16).
14. Using a test light connected to battery voltage, probe fuel pump ground terminal (body side). If test light illuminates, go to step 17). If test light does not illuminate, go to step 18).
15. Repair open in fuel pump feed circuit. After repairs, go to step 25).
16. Replace PCM. Perform PCM relearn procedures. After replacing PCM, go to step 25).
17. Check for an open in fuel pump feed circuit and ground circuit. Repair as necessary. After repairs, go to step 25). If circuit is okay, go to step 19).
18. Repair open in fuel pump ground circuit. After repairs, go to step 25).
19. Replace fuel pump. After replacing fuel pump, go to step 25).
20. Disconnect fuel pump connector at fuel pump. Remove fuel pump relay. Turn ignition off. Using a test light connected to battery voltage, probe fuel pump feed terminal. If test light illuminates, go to next step. If test light does not illuminate, go to step 22).
21. Repair short to ground in fuel pump circuit. After repairs, go to step 25).
22. Using a test light connected to battery voltage, probe fuel pump 6relay ignition feed terminal. If test light illuminates, go to next step. If test light does not illuminate, go to step 24).
23. Repair short to ground in fuel pump relay ignition feed circuit. After repairs, go to step 25).
24. Check for short to ground in fuel pump fuel pump feed circuit. Repair as necessary. After repairs, go to next step. If circuit is okay, go to step 19).
25. Using scan tool, clear DTC(s). Attempt to start engine. If engine starts and continues to run, go to next step. If engine does not start, or starts but dies, go to step 2).
26. Warm engine to operating temperature. Check for DTC(s). If DTC(s) is present, diagnose DTC(s). See TESTS W/CODES - 2.4L article. If DTC(s) is not present, system is okay.

BASIC FUEL SYSTEM CHECKS

Note. For fuel pump circuit testing, see FUEL SYSTEM ELECTRICAL CIRCUIT under NO START DIAGNOSIS .

FUEL SYSTEM PRESSURE RELIEF

Fuel system is under pressure. Pressure must be relieved prior to servicing fuel system. Fuel pressure may be relieved by using the following method.

1. Loosen fuel filler cap to relieve tank pressure (do not tighten at this time). Disconnect fuel pump connector. Start and run engine until it stalls. Crank starter for 3 seconds to remove remaining fuel from fuel lines. Turn ignition off. Reconnect fuel pump connector. Disconnect negative battery cable to avoid possible fuel discharge in accidental attempt to start engine.

FUEL SYSTEM PRESSURE TEST

1. Perform On-Board Diagnostic (OBD) System Check. See ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK in TESTS W/CODES - 2.4L article. After performing OBD system check, go to next step.
2. Turn ignition off. Turn A/C system off. Install Fuel Pressure Gauge (J-29658-D). This kit modifies fuel pressure gauge so it may be installed in fuel delivery line with quick-connect fittings. Place fuel pressure gauge bleed hose into container. Turn ignition on. Bleed air out of fuel pressure gauge. Turn ignition off for 10 seconds. Turn ignition on. Fuel pump should run for about 2 seconds. Cycle ignition to obtain highest fuel pressure possible. Observe fuel pressure with fuel pump running. Fuel pressure should be within specification. See «FUEL PRESSURE»(/chevrolet/malibu/v-1996-2000/remont/testing-diagnostics/#engine-controls-basic-diagnostic-procedures-24l) table. If fuel pressure is within specification, go to next step. If fuel pressure is not within specification, go to step 12).
3. Fuel pressure may vary slightly when fuel pump stops. After fuel pump stops, fuel pressure should stabilize and remain constant. Note fuel pressure when fuel pump stops running. If fuel pressure decreases more than 5 psi (0.3 kg/cm 2 ) in 10 minutes, go to step 10). If fuel pressure does not decrease more than 5 psi (0.3 kg/cm 2 ) in 10 minutes, go to next step.
4. Relieve fuel pressure until pressure is 10 psi (0.7 kg/cm 2 ). If fuel pressure decreases more than 2 psi (0.1 kg/cm 2 ) in 10 minutes, go to step 19). If fuel pressure does not decrease more than 2 psi (0.1 kg/cm 2 ) in 10 minutes, go to next step.
5. If fuel pressure is suspected of decreasing during acceleration, cruise or hard cornering, go to next step. If fuel pressure is not suspected of decreasing during acceleration, cruise or hard corning, go to step 8).
6. Inspect in-line fuel filter and fuel feed pipe for restriction. If restriction is found, go to step 24). If restriction is not found, go to next step.
7. Remove fuel sending unit assembly. Inspect fuel pump strainer for restriction, fuel pump strainer for proper positioning and installation on fuel sending unit assembly, fuel pump flex pipe for leaks, and ensure fuel pump is proper pump for vehicle. If a problem is found, go to step 24). If a problem is not found, go to step 19).
8. Turn ignition off for 10 seconds. Turn ignition on. Fuel pump should run for about 2 seconds. Cycle ignition to obtain highest fuel pressure possible. Note fuel pressure. Start engine. Allow engine to idle until normal operating temperature is reached. If fuel pressure is less than previously noted pressure by 3-10 psi (0.2-0.7 kg/cm 2 ), see TESTS W/O CODES - 2.4L article. If fuel pressure is greater than previously noted pressure by 3-10 psi (0.2-0.7 kg/cm 2 ), go to next step.
9. Disconnect vacuum hose from fuel pressure regulator. With engine idling, apply 12-14" of vacuum to fuel pressure regulator. If fuel pressure decreases by 3-10 psi (0.2-0.7 kg/cm 2 ), go to step 20). If fuel pressure does not decrease by 3-10 psi (0.2-0.7 kg/cm 2 ), go to step 21).
10. Turn ignition off. Relieve fuel pressure. See «FUEL SYSTEM PRESSURE RELIEF»(/chevrolet/malibu/v-1996-2000/remont/testing-diagnostics/#engine-controls-basic-diagnostic-procedures-24l__fuel-system-pressure-relief) . Place bleed hose into container. Turn ignition on. Bleed air out of fuel pressure gauge. Using scan tool, pressurize fuel system. DO NOT allow fuel pressure to exceed 65 psi (4.5 kg/cm 2 ). Excess pressure may damage fuel pressure regulator. Wait for fuel pressure to build. Using scan tool, obtain highest fuel pressure possible. Gradually pinch off fuel feed hose. If fuel pressure remains constant, go to step 19). If fuel pressure does not remain constant, go to next step.
11. Gradually unpinch fuel feed hose. Using scan tool, pressurize fuel system. Wait for fuel pressure to build. Gradually pinch off fuel return hose. If fuel pressure remains constant, go to step 21). If fuel pressure does not remain constant, go to step 22).
12. If fuel pressure is greater than specification, go to next step. See «FUEL PRESSURE»(/chevrolet/malibu/v-1996-2000/remont/testing-diagnostics/#engine-controls-basic-diagnostic-procedures-24l) table. If fuel pressure is less than specification, go to step 15).
13. Relieve fuel pressure. See «FUEL SYSTEM PRESSURE RELIEF»(/chevrolet/malibu/v-1996-2000/remont/testing-diagnostics/#engine-controls-basic-diagnostic-procedures-24l__fuel-system-pressure-relief) . Disconnect fuel return pipe from fuel rail. Attach a flexible fuel hose to fuel rail return outlet passage. Place other end of flexible hose into container. Turn ignition off for about 10 seconds. Turn ignition on. Observe fuel pressure gauge with fuel pump running. Fuel pressure should be within specification. See «FUEL PRESSURE»(/chevrolet/malibu/v-1996-2000/remont/testing-diagnostics/#engine-controls-basic-diagnostic-procedures-24l) table. If fuel pressure is within specification, go to step 23). If fuel pressure is not within specification, go to next step.
14. Inspect fuel rail outlet passage for restriction. If restriction is found, go to step 24). If restriction is not found, go to step 21).
15. If fuel pressure is greater than zero psi, go to next step. If fuel pressure is zero psi, go to step 17).
16. Turn ignition off. Relieve fuel pressure. See «FUEL SYSTEM PRESSURE RELIEF»(/chevrolet/malibu/v-1996-2000/remont/testing-diagnostics/#engine-controls-basic-diagnostic-procedures-24l__fuel-system-pressure-relief) . Place bleed hose into container. Turn ignition on. Bleed air out of fuel pressure gauge. Using scan tool, pressurize fuel system. DO NOT allow fuel pressure to exceed 65 psi (4.5 kg/cm 2 ). Excess pressure may damage fuel pressure regulator. Wait for fuel pressure to build. Using scan tool, obtain highest fuel pressure possible. Gradually pinch off fuel return hose. If fuel pressure increases to greater than specification, go to step 21). See «FUEL PRESSURE»(/chevrolet/malibu/v-1996-2000/remont/testing-diagnostics/#engine-controls-basic-diagnostic-procedures-24l) table. If fuel pressure does not increase to greater than specification, go to step 7).
17. Check fuel pump electrical circuit. See FUEL SYSTEM ELECTRICAL CIRCUIT under «NO START DIAGNOSIS»(/chevrolet/malibu/v-1996-2000/remont/testing-diagnostics/#engine-controls-basic-diagnostic-procedures-24l__no-start-diagnosis) . If a problem is found in electrical circuit, go to step 24). If electrical circuit is okay, go to next step.
18. Remove fuel sending unit assembly. Inspect in-line fuel filter for obstructions, fuel feed pipe for a restriction, fuel pump strainer for obstructions, and fuel pump flex pipe for leaks. If a problem is found, go to step 24). If a problem is not found, go to next step.
19. Replace fuel sending unit assembly. After replacing fuel sending unit assembly, go to step 25).
20. Locate and repair loss of vacuum to fuel pressure regulator. After repairing vacuum loss, go to step 25).
21. Replace fuel pressure regulator. After replacing fuel pressure regulator, go to step 25).
22. Locate and replace leaking fuel injector(s). After replacing fuel injector(s), go to step 25).
23. Locate and repair restriction in fuel return pipe. After repairing restriction, go to step 25).
24. Repair problem as necessary. After repairing problem, go to step 25).
25. Turn ignition off. Turn A/C system off. Install Fuel Pressure Gauge (J-29658-D). This kit modifies fuel pressure gauge so it may be installed in fuel delivery line with quick-connect fittings. Place fuel pressure gauge bleed hose into container. Turn ignition on. Bleed air out of fuel pressure gauge. Turn ignition off for 10 seconds. Turn ignition on. Fuel pump should run for about 2 seconds. Cycle ignition to obtain highest fuel pressure possible. Observe fuel pressure with fuel pump running. Fuel pressure should be within specification. See «FUEL PRESSURE»(/chevrolet/malibu/v-1996-2000/remont/testing-diagnostics/#engine-controls-basic-diagnostic-procedures-24l) table. If fuel pressure is within specification, go to next step. If fuel pressure is not within specification, go to step 11).
26. Fuel pressure may vary slightly when fuel pump stops. After fuel pump stops, fuel pressure should stabilize and remain constant. Note fuel pressure when fuel pump stops running. If fuel pressure decreases more than 5 psi (0.3 kg/cm 2 ) in 10 minutes, go to step 10). If fuel pressure does not decrease more than 5 psi (0.3 kg/cm 2 ) in 10 minutes, system is okay.

FUEL PRESSURE

Spark

1. Disconnect tachometer wire from IDI module (if equipped). A shorted tachometer will not allow vehicle to start. Temporarily remove IDI assembly and install Spark Plug Jumper Wires (J-36012). When removing spark plug wire from spark plug, twist and pull on boot. DO NOT pull on wire.
2. Using Spark Tester (J-26792), check for spark at each spark plug wire. Leave other wires connected while checking for spark. Check spark plug wire resistance on suspect wires. Resistance should be about 25,000 ohms.

Ignition Coil Power Source

Turn ignition on. Check ignition battery voltage circuit of ignition control module for battery voltage. See WIRING DIAGRAMS - 2.4L article. If battery voltage is not present, check ignition fuse. If fuse is not blown, check for open between fuse and ignition control module.

Ignition Coil Resistance

1. Disconnect ignition coil leads. Measure secondary coil resistance (secondary tower-to-secondary tower). Resistance should be 4000-8000 ohms. If resistance is not within specification, replace ignition coil.
2. Ignition coil primary resistance value is not available at time of publication. If ignition coil is suspected of causing a misfire or a no-spark condition, switch coil locations on ignition control module. If problem follows questionable coil, replace original coil.

Crankshaft Position (CKP) Sensor Pick-Up Coil Short & Resistance Checks

1. Set DVOM on 2000-ohm scale. Connect DVOM leads to CKP sensor connector located on side of engine block. Turn ignition off. Disconnect ignition control module connectors. Check resistance between CKP sensor terminals at ignition control module connector.
2. CKP sensor resistance should be 500-900 ohms. If resistance is not as specified, replace CKP sensor. If sensor is within specification, go to next step.
3. With CKP sensor installed in block, connect one ohmmeter lead to either sensor terminal at ignition control module. Touch other lead of ohmmeter to engine block. No continuity should exist. If continuity exists, CKP sensor is shorted to ground and must be repaired or replaced.

Crankshaft Position (CKP) Sensor Output Signal

Set DVOM on 2-volt AC scale. Connect DVOM leads to CKP sensor located on side of engine block. Crank engine and observe voltmeter reading. CKP sensor should generate a voltage signal of about 1100-1300 millivolts as crankshaft turns. Ignition control module can be triggered with a voltage signal as low as 200 millivolts.

Tach Pulse (RPM) Signal

Connect scan tool to DLC. RPM should be indicated on scan tool when engine is cranked or running. Tach pulse (RPM reference) will be indicated as a voltage signal when a DVOM (with a minimum 10-megohm input impedance connected to ground) is used to backprobe RPM high reference circuit. If tach pulse signal is not present, vehicle will not run. For circuit and terminal identification, see WIRING DIAGRAMS - 2.4L article.

IDLE SPEED & IGNITION TIMING

Ensure idle speed and ignition timing are set to specification. For specifications, see SPECIFICATIONS - 2.4L article. For adjustment procedures, see ADJUSTMENTS - 2.4L article.

SUMMARY

If no faults were found while performing BASIC DIAGNOSTIC PROCEDURES, no trouble codes (or only intermittent ones) were found while performing ON-BOARD DIAGNOSTIC SYSTEM CHECK and driveability problems exist, proceed to appropriate H - TESTS W/O CODES - 2.4L article for diagnosis by symptom (i.e., ROUGH IDLE, NO-START, etc.) or intermittent diagnostic procedures.

See also:
• BASIC FUEL SYSTEM CHECKS
• NO START DIAGNOSIS
• FUEL PRESSURE
• FUEL SYSTEM PRESSURE RELIEF