Engine Control System - Basic Engine Testing - 3.8L: Other Pontiac Firebird IV

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 the SPECIFICATIONS 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.

DEFINITION

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

NO START - ENGINE CRANKS OKAY

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

Ignition System

1. Perform On-Board Diagnostic (OBD) System Check. See «ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK»(ref-20653-S16109918862001010200000) . After performing OBD system check, go to next step.
2. Turn ignition on. Using scan tool, select FAILED SINCE CODE CLEAR function. If Diagnostic Trouble Code (DTC) P0123, P0506, P0507, P0601, P0602 or P1629 is present, diagnose applicable DTC. See the TESTS W/CODES article. If DTC is not present, go to next step.
3. Check Ignition Control Module (ICM) ignition feed circuit fuse. If fuse is blown, locate and repair short to ground in ICM ignition feed circuit or short to voltage in IC circuit. After repairs, perform «ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK»(ref-20653-S16109918862001010200000) . If fuse is okay, go to next step.
4. Using scan tool, observe engine speed display while cranking engine. If RPM is indicated, go to next step. If RPM is not indicated, go to step 23).
5. Turn ignition off. Disconnect injector connector. Install Injector Test Light (J-34730-2) to injector connector. See the WIRING DIAGRAMS article. Turn ignition on. If injector test lights illuminates, go to step 18). If injector test lights does not illuminate, go to next step.
6. Crank engine and monitor injector test lights. If all injector test lights flash, go to next step. If any of injector test light does not flash, go to step 19).
7. Turn ignition off. Install fuel pressure gauge to fuel injector test fitting. Turn ignition on and observe fuel pressure. Fuel pressure should be 48-55 psi (3.4-3.9 kg/cm 2 ) and hold steady. If fuel pressure is as specified, go to step 9). If fuel pressure is not as specified, go to next step.
8. If fuel pressure is indicated, but not as specified, diagnose fuel system. See «BASIC FUEL SYSTEM CHECKS»(ref-20653-S02141675012001010200000) . If fuel pressure is not present, go to FUEL SYSTEM.
9. Check for fuel contamination. If fuel is contaminated, clean fuel system. After repairs, perform «ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK»(ref-20653-S16109918862001010200000) . If fuel is not contaminated, go to next step.
10. Install Spark Tester (J-26792) to cylinder No. 1, 2 and 3 (one at a time). Connect the spark plug wire of companion cylinder to ground (i.e., 1/4, 2/5, 3/6). Crank engine and observe spark tester. If spark is present, go to next step. If spark is not present, go to step 12).
11. Remove and inspect spark plugs from all cylinders. If spark plugs are okay, go to step 37). If spark plugs shows excessive fouling, check engine for mechanical problems.
12. If spark is present at any ignition wire, go to next step. If spark is not present at any ignition wire, go to step 40).
13. Remove and inspect ignition coil to affected cylinder for cracks or carbon tracking. Replace faulty ignition coil(s) as necessary. After repairs, perform «ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK»(ref-20653-S16109918862001010200000) . If coil(s) are okay, go to next step.
14. Check secondary ignition resistance. Resistance should be 5000-8000 ohms. Replace faulty ignition coil(s) as necessary. After repairs, perform «ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK»(ref-20653-S16109918862001010200000) . If resistance is as specified, go to next step.
15. Remove and inspect ignition wire to affected cylinder for cracks or carbon tracking. Replace faulty ignition wire(s) as necessary. After repairs, perform «ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK»(ref-20653-S16109918862001010200000) . If wire(s) are okay, go to next step.
16. Check ignition wire resistance. Resistance should be about 30,000 ohms. Replace faulty ignition wire(s) as necessary. After repairs, perform «ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK»(ref-20653-S16109918862001010200000) . If resistance is not as specified, go to next step.
17. Connect test light across Ignition Control Module (ICM) primary circuit (between ICM control terminals) for coils associated with cylinder that did not have a spark. Crank engine. If test light flashes, go to step 39). If test light does not flash, go to step 40).
18. Turn ignition off. Disconnect PCM connector. Turn ignition on. Observe injector test lights. If injector test lights illuminate, go to step 34). If injector test lights does not illuminate, go to step 38).
19. If any injector test light flashes, go to next step. If no injector test light flashes, go to step 22).
20. Disconnect injector test light that did not flash when engine was being cranked. Turn ignition on. Using a test light connected to ground, probe ignition feed circuit at each injector connector. See the WIRING DIAGRAMS article. If test light illuminates on all injector connectors, go to next step. If test light does not illuminate on all injector connectors, go to step 35).
21. Turn ignition off. Disconnect PCM connector. Check affected injector circuit driver for an open. See the WIRING DIAGRAMS article. Repair open circuit as necessary. After repairs, perform «ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK»(ref-20653-S16109918862001010200000) . If circuit is okay, go to step 38).
22. Turn ignition off. Disconnect Ignition Control Module (ICM) connector. Turn ignition on. Using a test light connected to ground, probe ignition control module ignition feed circuit at connector. See the WIRING DIAGRAMS article. If test light illuminates, go to step 24). If test light does not illuminate, go to next step.
23. Check fuse to ignition control module feed circuit. See the WIRING DIAGRAMS article. If fuse is faulty, locate and repair short to ground in ignition feed circuit. After repairs, perform «ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK»(ref-20653-S16109918862001010200000) . If fuse is okay, go to step 36).
24. Install an injector test light to any injector connector. Turn ignition on. Using a test light connected to battery voltage, repeatedly touch test light to 3X reference circuit at ICM connector. See the WIRING DIAGRAMS article. If injector test light flashes, go to next step. If injector test light does not flash, go to step 33).
25. Turn ignition off. Using a fused jumper wire, jumper Crankshaft Position (CKP) sensor ignition feed circuit at ICM connector to battery voltage. Connect a second jumper between ground and CKP sensor ground circuit at ICM connector. Connect DVOM between battery voltage and CKP sensor signal circuit at ICM connector. Crank engine and observe DVOM voltage reading. Voltage should be 1-3 volts. If voltage reading is as specified, go to step 29). If voltage reading is not as specified, go to next step.
26. If voltage reading is greater than 3 volts, go to next step. If voltage reading is less than 3 volts, go to step 28).
27. Disconnect CKP sensor connector. Using a test light connected to battery voltage, probe CKP sync signal circuit. See the WIRING DIAGRAMS article. If test light illuminates, locate and repair short to ground in CKP sync signal circuit. After repairs, perform «ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK»(ref-20653-S16109918862001010200000) . If test light does not illuminate, go to step 41).
28. Check open or short to voltage in CKP sensor sync signal circuit, open in CKP sensor ground circuit, or open or short to ground in CKP sensor feed circuit. See the WIRING DIAGRAMS article. Repair as necessary. After repairs, perform «ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK»(ref-20653-S16109918862001010200000) . If no circuit problems are found, go to step 41).
29. Connect DVOM between battery voltage and 18X reference circuit at ICM connector. Crank engine and observe DVOM voltage reading. Voltage should be 5-7 volts. If voltage reading is as specified, go to step 40). If voltage reading is not as specified, go to next step.
30. If voltage reading is greater than 7 volts, go to next step. If voltage reading is less than 7 volts, go to step 32).
31. Disconnect CKP sensor connector. Using a test light connected to battery positive, probe 18X reference circuit terminal. See the WIRING DIAGRAMS article. If test light illuminates, locate and repair short to ground in 18X reference circuit. After repairs, perform «ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK»(ref-20653-S16109918862001010200000) . If circuit is okay, go to step 41).
32. Check for open or short to voltage in 18X reference circuit. Repair as necessary. After repairs, perform «ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK»(ref-20653-S16109918862001010200000) . If circuit is okay, go to step 41).
33. Turn ignition off. Disconnect PCM connector. Check for open or short in 3X reference circuit. Repair as necessary. After repairs, perform «ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK»(ref-20653-S16109918862001010200000) . If circuit is okay, go to step 38).
34. Locate and repair short to ground in injector driver circuit(s) to affected injector (test light stayed on). See the WIRING DIAGRAMS article. After repairs, perform «ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK»(ref-20653-S16109918862001010200000) .
35. Locate and repair open in fuel injector ignition feed circuit. See the WIRING DIAGRAMS article. After repairs, perform «ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK»(ref-20653-S16109918862001010200000) .
36. Locate and repair open in ICM ignition feed circuit. See the WIRING DIAGRAMS article. After repairs, perform «ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK»(ref-20653-S16109918862001010200000) .
37. Repair engine mechanical problem. Check for bent push rods, faulty or incorrect camshaft, leaking or sticky valves or rings, excessive valve deposits, loose or worn rocker arms, weak valve springs, incorrect valve timing or a leaking head gasket. Repair as necessary. After repairs, perform «ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK»(ref-20653-S16109918862001010200000) .
38. Replace PCM. Perform PCM relearn procedures. After replacing PCM, perform «ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK»(ref-20653-S16109918862001010200000) .
39. Replace affected ignition coil(s) that did not produce a spark. After repairs, perform «ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK»(ref-20653-S16109918862001010200000) .
40. Replace ICM. After repairs, perform «ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK»(ref-20653-S16109918862001010200000) .
41. Replace CKP sensor. After repairs, perform «ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK»(ref-20653-S16109918862001010200000) .

Fuel System (VIN K)

1. Perform On-Board Diagnostic (OBD) System Check. See «ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK»(ref-20653-S16109918862001010200000) . After performing OBD system check, go to next step.
2. Turn ignition off. Install fuel pressure gauge to fuel pressure test port. Remove fuel pump relay. Using a fused jumper wire, jumper fuel pump feed circuit at fuel pump relay connector to battery voltage. Fuel pressure should be 48-55 psi (3.4-3.9 kg/cm 2 ). If fuel pressure is as specified, go to next step. If fuel pressure is not as specified, go to step 10).
3. Disconnect jumper from fuel pump relay connector. Connect test light between fuel pump relay connector ignition feed circuit and ground circuit. See the WIRING DIAGRAMS article. Turn ignition on. If test light illuminates, go to next step. If test light does not illuminate, go to step 9).
4. Turn ignition off. Connect test light between fuel pump relay connector fuel pump relay driver circuit and ground circuit. See the WIRING DIAGRAMS article. Turn ignition on. Test light should illuminate for about 2 seconds. If test light illuminates, go to step 8). If test light does not illuminate, go to next step.
5. Turn ignition off. Disconnect PCM connector. Using a test light connected to battery voltage, probe fuel pump driver circuit at PCM connector. See the WIRING DIAGRAMS article. If test light illuminates, go to step 15). If test light does not illuminate, go to next step.
6. Check continuity of fuel pump relay driver circuit between PCM and fuel pump relay. Repair open in circuit as necessary. After repairs, go to step 21). If circuit is okay, go to next step.
7. Check fuel pump relay driver circuit for poor terminal connection at PCM. If connection is faulty, repair as necessary. After repairs, go to step 21). If connection is okay, go to step 18).
8. Check fuel pump relay terminal connection. If connection is faulty, repair as necessary. After repairs, go to step 21). If connection is okay, go to step 18).
9. Using a test light connected to ground, probe ignition feed circuit at fuel pump relay connector. See the WIRING DIAGRAMS article. If test light illuminates, go to step 17). If test light does not illuminate, go to step 16).
10. Remove fuel filler cap and listen for fuel pump operation. If fuel pump is running, diagnose fuel system. See «BASIC FUEL SYSTEM CHECKS»(ref-20653-S02141675012001010200000) . If fuel pump is not running, go to next step.
11. Using a fused jumper wire, connect battery voltage to fuel pump feed circuit. See the WIRING DIAGRAMS article. Raise and support vehicle. Disconnect fuel sending unit connector at fuel tank. Using a test light, check voltage between fuel sending unit connector terminals. If test light illuminates, go to step 19). If test light does not illuminate, go to next step.
12. Using a test light connected to ground, probe fuel pump feed circuit at fuel sending unit connector. If test light does not illuminate, go to next step. If test light illuminates, go to step 14).
13. Locate and repair open in fuel pump feed circuit. After repairs, go to step 21).
14. Locate and repair open in fuel pump ground circuit. After repairs, go to step 21).
15. Locate and repair short to ground in fuel pump relay driver circuit. After repairs, go to step 21).
16. Locate and repair open in ignition feed circuit to fuel pump relay. After repairs, go to step 21).
17. Locate and repair open in ground circuit to fuel pump relay. After repairs, go to step 21).
18. Replace fuel pump relay. After fuel pump relay replacement, go to step 21).
19. Replace fuel pump. After fuel pump replacement, go to step 21).
20. Replace PCM. Perform PCM relearn procedures. After PCM replacement, go to next step.
21. Turn ignition on. Using scan tool, select FP RELAY OUTPUT CONTROL function. Observe fuel pressure gauge while activating fuel pump with scan tool. Fuel pressure should be 48-55 psi (3.4-3.9 kg/cm 2 ). If fuel pressure is not as specified, repeat step 2). If fuel pressure is as specified, system is okay.

Fuel System (VIN 1)

1. Perform On-Board Diagnostic (OBD) System Check. See «ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK»(ref-20653-S16109918862001010200000) . After performing OBD system check, go to next step.
2. If Diagnostic Trouble Code (DTC) P1643 is present, diagnose DTC. See the TESTS W/CODES article. If DTC is not present, go to next step.
3. Turn ignition off. Install fuel pressure gauge to fuel pressure test port. Using a scan tool, select FP RELAY OUTPUT CONTROL function. Observe fuel pressure gauge while activating fuel pump with scan tool. Fuel pressure should be 48-55 psi (3.4-3.9 kg/cm 2 ). If fuel pressure is as specified, go to next step. If fuel pressure is not as specified, go to step 5).
4. Start engine. Using scan tool, switch fuel pump speed between normal and high. Fuel pressure should slightly increase when high fuel pump speed is selected. If fuel pressure increases, no trouble is found. If fuel pressure does not change, go to step 31).
5. Turn ignition off. Disconnect fuel pump control module. Using a fused jumper wire, jumper fuel pump feed circuit of fuel pump control module connector to battery voltage. See the WIRING DIAGRAMS article. Connect a second jumper wire between ground circuit of fuel pump control module connector and ground. Observe fuel pressure gauge. Fuel pressure should be 48-55 psi (3.4-3.9 kg/cm 2 ). If fuel pressure is as specified, go to next step. If fuel pressure is not as specified, go to step 26).
6. Disconnect jumpers from fuel pump control module connector. Connect test light between fuel pump control module connector feed circuit and ground circuit. Turn ignition on. Using scan tool, activate fuel pump. If test light illuminates, go to next step. If test light does not illuminate, go to step 13).
7. Using a test light connected to battery voltage, probe fuel pump control module ground circuit. If test light illuminates, go to next step. If test light does not illuminate, go to step 25).
8. Turn ignition off. Disconnect PCM connector. Using a test light connected to battery voltage, probe fuel pump driver circuit at PCM connector. If test light illuminates, go to next step. If test light does not illuminate, go to step 10).
9. Locate and repair short to ground in fuel pump driver circuit. After repairs, go to step 39).
10. Turn ignition off. Reconnect PCM connector. Turn ignition on. Connect DVOM between fuel pump control module connector fuel pump driver circuit and ground circuit. Using scan tool, command fuel pump on and off. DVOM should read greater than 8 volts while fuel pump relay is commanded on. If voltage is as specified, go to next step. If voltage is not as specified, go to step 38).
11. Turn ignition off. Reconnect fuel pump control module connector. Turn ignition on. Connect test light between fuel pump control module connector fuel pump feed circuit and ground circuit. Using scan tool, command fuel pump relay on and off. Test light should illuminate when fuel pump is commanded on. If test light illuminates, go to next step. If test light does not illuminate, go to step 34).
12. Check for poor terminal connection at fuel pump control module. Repair connection as necessary. After repairs, go to step 39). If connection is okay, check PCM and connectors for improper mating, check for rubbed through wire insulation or a wire broken inside insulation.
13. Turn ignition off. Remove fuel pump relay. Turn ignition on. Using a test light connected to ground, probe fuel pump relay connector ignition feed circuit. See the WIRING DIAGRAMS article. If test light illuminates, go to next step. If test light does not illuminate, go to step 19).
14. Connect test light between fuel pump relay connector feed circuit and ground circuit. See the WIRING DIAGRAMS article. If test light illuminates, go to next step. If test light does not illuminate, go to step 20).
15. Connect test light between fuel pump relay connector driver circuit and ground circuit. See the WIRING DIAGRAMS article. Using scan tool, command fuel pump relay on. If test light illuminates when fuel pump relay is on, go to next step. If test light does not illuminate, go to step 21).
16. Connect jumper wire between fuel pump relay connector feed circuit and fuel pump control module connector feed circuit. Using a test light connected to ground, probe fuel pump control module connector feed circuit. If test light does not illuminate, go to step 24). If test light illuminates, go to next step.
17. Check for faulty terminal connection at fuel pump relay. Repair as necessary. After repairs, go to step 39). If terminals are okay, go to next step.
18. Replace fuel pump relay. After repairs, go to step 39).
19. Locate and repair open in fuel pump relay feed circuit. After repairs, go to step 39).
20. Locate and repair open in fuel pump relay ground circuit. After repairs, go to step 39).
21. Turn ignition off. Disconnect PCM connector. Using a test light connected to battery voltage, probe fuel pump relay driver circuit at PCM connector. If test light illuminates, go to next step. If test light does not illuminate, go to step 23).
22. Locate and repair short to ground in fuel pump relay driver circuit. After repairs, go to step 39).
23. Check fuel pump relay driver circuit for poor connection or open circuit between fuel pump relay and PCM. Repair as necessary. After repairs, go to step 39). If connection and circuit are okay, go to next step.
24. Locate and repair open in fuel pump control module feed circuit. After repairs, go to step 39).
25. Locate and repair open in fuel pump control module ground circuit. After repairs, go to step 39).
26. Remove fuel filler cap and listen for fuel pump operation. If fuel pump is running, diagnose fuel system. See «BASIC FUEL SYSTEM CHECKS»(ref-20653-S02141675012001010200000) . If fuel pump is not running, go to next step.
27. Using fused jumper wires, connect battery voltage to fuel pump feed circuit and ground to fuel pump ground circuit. Raise and support vehicle. Disconnect fuel sending unit connector at fuel tank. Using a test light, check fuel sending unit circuit between connector terminals. If test light illuminates, go to step 36). If test light does not illuminate, go to next step.
28. Using a test light connected to ground, probe fuel pump feed circuit at fuel sending unit connector. See the WIRING DIAGRAMS article. If test light does not illuminate, go to next step. If test light illuminates, go to step 30).
29. Locate and repair open in fuel pump feed circuit. After repairs, go to step 39).
30. Locate and repair open in fuel pump ground circuit. After repairs, go to step 39).
31. Connect test light between fuel pump control module fuel pump PWM driver circuit and fuel pump controller feed circuit. Start and idle engine. Using scan tool, select FP SPEED OUTPUT CONTROL function. Observe test light while switching scan tool between normal and high. Test light should illuminate when normal is selected, then turn off when high is selected. If test light illuminates as indicated, go to next step. If test light does not illuminate as indicated, go to step 33).
32. Connect DVOM between fuel pump ground circuit and fuel pump feed circuit of fuel pump control module. Start and idle engine. Using scan tool, select FP SPEED OUTPUT CONTROL function. Observe DVOM voltage reading while switching scan tool between normal and high speed. On normal speed, DVOM should read about 7.0 volts. On high speed, DVOM should read battery voltage. If voltage readings are as specified, go to step 36). If voltage readings are not as specified, go to step 34).
33. Check fuel pump PWM driver circuit for poor terminal connection, or an open or short to voltage between fuel pump control module and PCM. Repair terminal or circuit as necessary. After repairs, go to step 39). If circuit or terminal is okay, go to step 38).
34. Check fuel pump control module terminal connection. If terminals are faulty, repair or replace as necessary. After repairs, go to step 39). If terminals are okay, go to next step.
35. Replace fuel pump control module. After fuel pump control module replacement, go to step 39).
36. Check fuel pump terminal connection. If terminals are faulty, repair or replace as necessary. After repairs, go to step 39). If terminals are okay, go to next step.
37. Replace fuel pump. After fuel pump replacement, go to step 39).
38. Replace PCM. Ensure PCM relearn procedure is performed. After repairs, go to next step.
39. Turn ignition on. Using scan tool, select FP RELAY OUTPUT CONTROL function. Using scan tool, command fuel pump on. Fuel pressure should be 48-55 psi (3.4-3.9 kg/cm 2 ). If fuel pressure is as specified, go to next step. If fuel pressure is not as specified, go to step 5).
40. Start and idle engine. Using scan tool, select FP RELAY CONTROL OUTPUT function. Observe fuel pressure while switching scan tool between normal and high. Fuel pressure should slightly increase when high speed is selected. If fuel pressure does not slightly increase, go to step 31). If fuel pressure increases as specified, system is okay.

BASIC FUEL SYSTEM CHECKS

Fuel Pressure Relief

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

1. Disconnect negative battery terminal. Loosen fuel filler cap. Install Fuel Pressure Gauge (J-34730-1) on fuel pressure connector of fuel rail. Wrap shop towel around pressure connection when installing fuel pressure gauge to absorb fuel leakage. Install gauge bleed hose in container. Open bleed valve to bleed fuel pressure.

Fuel Pressure Check

1. Relieve fuel pressure. See FUEL PRESSURE RELIEF. Connect Fuel Pressure Gauge (J-34730-1) to fuel pressure fitting on fuel rail. Turn ignition on with engine off. Fuel pressure should be within specification. See «FUEL PRESSURE»(ref-20653-S32358841592001010200000) table. If no fuel pressure is present, go to step 5).
2. Start engine. Fuel pressure should drop 3-10 psi (.2-.7 kg/cm 2 ). Turn ignition off. Pressure should hold. If fuel pressure does not hold, check for leaking injectors or fittings. If injectors or fittings are not leaking, replace fuel pressure regulator.
3. If fuel pressure is less than specified, check for restricted fuel line or fuel filter. Repair as necessary. If no restriction is evident, apply battery voltage to fuel pump test connector using a 10-amp fused jumper wire. For location of fuel pump test connector, see COMPONENT LOCATIONS in the SYSTEM/COMPONENT TESTS article.
4. Gradually pinch off fuel return line between gauge and fuel tank. If fuel pressure increases to within specification, replace fuel pressure regulator. If fuel pressure does not increase with line pinched, check for faulty in-tank fuel pump or partially blocked fuel strainer.
5. Using a 10-amp fused jumper wire, apply battery voltage to fuel pump test connector. For location of fuel pump test connector, see COMPONENT LOCATIONS in the SYSTEM/COMPONENT TESTS article. Observe fuel pressure reading. If fuel pressure is still not present, check wiring between test connector and fuel pump. If wiring is okay, replace fuel pump.
6. If fuel pressure is present with voltage applied to test connector, test fuel pump relay and voltage supply to relay. See the SYSTEM/COMPONENT TESTS article.

FUEL PRESSURE

Fuel Pump Relay

See MOTORS, RELAYS & SOLENOIDS in the SYSTEM/COMPONENT TESTS article.

Fuel Pump Relay By-Pass Procedure

See FUEL DELIVERY in the SYSTEM/COMPONENT TESTS article.

Spark

Disconnect tachometer wire (if equipped). A shorted tachometer will prevent vehicle from starting. Disconnect Camshaft Position (CMP) sensor. Attempt to start engine. If engine starts, see appropriate CMP sensor DTC in the TESTS W/CODES article. Using Spark Tester (J-26792), check for adequate spark. Check for spark on plug wires No. 1, 3 and 5 (one at a time). Leave matching plug wire connected while checking for spark. When removing spark plug wire from spark plug, twist and pull on boot. DO NOT pull on wire.

Ignition Coil Power Source

Turn ignition on. Check for battery voltage on ignition positive voltage circuit to ignition control module. If battery voltage is not present, check for blown ignition fuse. If fuse is not blown, check for open between fuse and ignition control module.

Ignition Coil Resistance

Disconnect ignition coil leads. Using an ohmmeter, check ignition coil resistance. Secondary resistance should be 5000-8000 ohms. If resistance is not as specified, replace ignition coil.

IDLE SPEED & IGNITION TIMING

Ensure idle speed and ignition timing are set to specification. For adjustment procedures, see the ADJUSTMENTS article.

MIL INOPERATIVE

1. Perform On-Board Diagnostic (OBD) System Check. See «ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK»(ref-20653-S16109918862001010200000) . After performing OBD system check, go to next step.
2. Attempt to start engine. If engine starts, go to next step. If engine does not start, go to step 6).
3. Check instrument cluster ignition feed fuse. If fuse is okay, go to next step. If fuses are blown, go to step 15).
4. Turn ignition on. Using a test light connected to ground, probe instrument cluster connector ignition feed circuit. See the WIRING DIAGRAMS article. If test light illuminates, go to next step. If test light does not illuminate, go to step 12).
5. Turn ignition off. Disconnect PCM connector. Turn ignition on. Using a jumper wire connected to ground, jumper PCM connector MIL driver circuit. See the WIRING DIAGRAMS article. If MIL illuminates, go to step 10). If MIL does not illuminate, go to step 11).
6. Check PCM ignition feed and battery feed fuses. If fuses are okay, go to next step. If fuses are blown, go to step 14).
7. Turn ignition off. Disconnect PCM connector. Turn ignition on. Using a test light connected to ground, probe PCM connector ignition feed circuit. See the WIRING DIAGRAMS article. If test light illuminates, go to next step. If test light does not illuminate, go to step 13).
8. Using a test light connected to ground, probe PCM connector battery feed circuit. See the WIRING DIAGRAMS article. If test light illuminates, go to next step. If test light does not illuminate, go to step 13).
9. Check for poor PCM ground or PCM ground connection. Repair as necessary. After repairs, perform «ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK»(ref-20653-S16109918862001010200000) . If ground and ground connection are okay, go to next step.
10. Check for poor PCM connection. Repair as necessary. After repairs, perform «ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK»(ref-20653-S16109918862001010200000) . If connection is okay, go to step 16).
11. Check for open in MIL driver circuit. See the WIRING DIAGRAMS article. Repair as necessary. After repairs, perform «ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK»(ref-20653-S16109918862001010200000) . If circuit is okay, go to step 17).
12. Repair open in instrument cluster ignition feed circuit. Repair as necessary. After repairs, perform «ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK»(ref-20653-S16109918862001010200000) .
13. Locate and repair open in PCM battery feed circuit or PCM ignition feed circuit. Repair as necessary. After repairs, perform «ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK»(ref-20653-S16109918862001010200000) .
14. Locate and repair short to ground in PCM battery feed circuit or PCM ignition feed circuit. Repair as necessary. After repairs, perform «ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK»(ref-20653-S16109918862001010200000) .
15. Locate and repair short to ground in instrument cluster ignition feed circuit. Repair as necessary. After repairs, perform «ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK»(ref-20653-S16109918862001010200000) .
16. Replace PCM. Perform PCM relearn procedures. After repairs, perform «ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK»(ref-20653-S16109918862001010200000) .
17. Check for poor instrument cluster MIL driver circuit connection. Repair as necessary. After repairs, perform «ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK»(ref-20653-S16109918862001010200000) . If connection is okay, diagnose instrument cluster.

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 the TESTS W/O CODES article for diagnosis by symptom (i.e., ROUGH IDLE, NO-START, etc.) or intermittent diagnostic procedures.