Engine Control System - Basic Engine Testing: Diagnosis Saturn SL II

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 appropriate VACUUM DIAGRAMS article to verify routing and connections. Inspect air induction system for possible vacuum leaks.

Diagnosis

1. Start engine and allow it to reach normal 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 necessary.

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 appropriate wiring diagram in WIRING DIAGRAMS article.

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

Diagnostic Procedure

1. Install scan tool. Perform On-Board Diagnostic (OBD) system check. See ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK in appropriate SELF-DIAGNOSTICS article. Check for stuck Throttle Position (TP) sensor. Ensure Engine Coolant Temperature (ECT) sensor value reads close to ambient temperature. Check for fuel injector Diagnostic Trouble Codes (DTCs). If fuel injector DTCs are present, diagnose DTCs first. See appropriate SELF-DIAGNOSTICS article. If fuel injector DTCs are not present, go to next step.
2. If DTC P1635 is present, diagnose DTC first. See appropriate SELF-DIAGNOSTICS article. If DTC P1635 is not present, go to next step.
3. If any Ignition Control (IC) related DTC is present, diagnose DTC first. See appropriate SELF-DIAGNOSTICS article. If DTC is not present, go to next step.
4. If an EGR related DTC is present, diagnose DTC first. See appropriate SELF-DIAGNOSTICS article. If EGR DTC is not present, go to next step.
5. Using scan tool, monitor engine RPM (7X CKP reference pulse) while cranking engine. If RPM is detected, go to next step. If RPM is not detected, go to step 15.
6. If scan tool 7X counter reads more than 100 counts, go to next step. If scan tool 7X counter reads 100 counts or less, go to step 10.
7. Check for spark at cylinders No. 2 and 4. If spark is present, check for fouled spark plugs. If spark plugs are okay, go to step 11. If spark is not present, go to next step.
8. Check EIS fuse (10-amp), located in underhood fuse block, or voltage to fuse with ignition on. (Scheme 1) If fuse is okay and voltage is present, go to next step. If fuse is faulty or voltage is not present, replace fuse or repair circuit.
9. Disconnect Electronic Ignition (EI) module harness connector. Turn ignition on. Using a test light, check for voltage between ground and terminal "A" at EI module harness connector. (Scheme 1) If voltage is present, check EI module connector tightness. If connector is okay, EI module is faulty. If voltage is not present, repair open in Pink wire (circuit No. 1039) between EI module and instrument panel fuse block.
10. Check for spark at plug wires of cylinders No. 2 and 4. If spark is present at both wires, go to next step. If spark is not present at either plug wire, check for 12 volts and ground to EI module. (Scheme 1) Repair as necessary. If spark is present at only one plug wire, check spark at opposing cylinder. If spark is present at opposing cylinder, replace spark plug wire. If spark is not present at opposing cylinder, replace EI module.
11. Reconnect EI module harness connector. Install Fuel Pressure Gauge (SA9127E). Turn ignition on. Fuel pressure reading should be 38-44 psi (2.7-3.1 kg/cm 2 ). If fuel pressure is as specified, see appropriate TROUBLE SHOOTING - NO CODES article. If fuel pressure is not as specified, go to next step.
12. Turn ignition off. Using a test light connected to ground, probe FUEL PUMP fuse (10-amp), located in instrument panel fuse block. (Scheme 2) Turn ignition on. Test light should illuminate for 2 seconds, and then turn off. If test light illuminates and turns off after about 2 seconds, check for open in fuel pump circuit (Gray wire) or ground circuit (Black wire). If circuits are okay, check fuel pump. If test light does not illuminate, go to next step.
13. Turn ignition off. Repeat test with test light inserted in instrument panel fuse block probe hole. (Scheme 2) If test light does not illuminate, check for open or short to ground in Dark Green/White wire between fuel pump relay and PCM. If circuit is okay, check PCM connector tightness or for faulty PCM. If test light illuminates, go to next step.
14. Remove fuel pump relay. Using a test light connected to ground, probe Red wire terminal of fuel pump relay connector (relay socket) in instrument panel fuse block. (Scheme 2) If test light illuminates, check fuel pump relay connector tightness. Check for faulty fuel pump relay ground or for faulty fuel pump relay. If test light does not illuminate, check for faulty I/P BATT fuse (30-amp), located in underhood fuse block. If fuse is okay, repair open in Red wire between fuel pump relay and underhood fuse block.
15. Turn ignition off. Disconnect PCM connector J3. (Scheme 1) Using DVOM, measure resistance between PCM connector J3, terminals D13 (7X ref hi circuit) and D14 (7X ref lo circuit). Resistance should be 700-900 ohms. If resistance is as specified, go to next step. If resistance is not as specified, go to step 17.
16. Set DVOM to AC scale. Connect DVOM between PCM connector J3, terminals D13 (7X ref hi circuit) and D14 (7X ref lo circuit). (Scheme 1) Crank engine. DVOM should display 200 millivolts. If voltage is as specified, check PCM connector tightness. If voltage is not as specified, replace Crankshaft Position (CKP) sensor.
17. Check for continuity in 7X ref hi circuit (Yellow wire) and 7X ref lo circuit (Purple wire). (Scheme 1) Repair as necessary. If continuity is present, check circuits for short to ground or voltage. Repair as necessary. If circuits are okay, go to next step.
18. Remove Crankshaft Position (CKP) sensor. Measure CKP sensor resistance. Resistance should be 700-900 ohms. If resistance is not as specified, replace CKP sensor. If resistance is as specified, go to next step.
19. Check if CKP sensor is still magnetized. If sensor is not magnetized, replace CKP sensor. If sensor is magnetized, check for poor or intermittent connection at sensor connector. Repair as necessary.

Scheme 1

Scheme 2

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.

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 secondary boots 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.

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 (VECI) 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.

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 (VECI) 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.

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 (VECI) 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.

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 (VECI) 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.

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 (VECI) 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.

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 (VECI) 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.

FUEL SYSTEM PRESSURE TEST (EXCEPT SATURN)

1. Perform On-Board Diagnostic (OBD) system check. See ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK in appropriate SELF-DIAGNOSTICS article. After performing OBD system check, go to next step.
2. Turn ignition off. Turn A/C system off. On all models except 2.2L and 2.4L, connect Fuel Pressure Gauge (J-34730-1A) to fuel pressure fitting on fuel rail. On 2.2L and 2.4L, 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. On all models, 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 (EXCEPT SATURN)»(ref-172-S13169501982000030800000) 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 and correct installation. Check fuel pump flex pipe for leaks, and ensure fuel pump is correct for application. 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 appropriate TROUBLE SHOOTING - NO CODES 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 (EXCEPT SATURN)»(ref-172-S18951447162000030800000) . 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 (EXCEPT SATURN)»(ref-172-S13169501982000030800000) table. If fuel pressure is less than specification, go to step 15 .
13. Relieve fuel pressure. See «FUEL SYSTEM PRESSURE RELIEF (EXCEPT SATURN)»(ref-172-S18951447162000030800000) . 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 (EXCEPT SATURN)»(ref-172-S13169501982000030800000) 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 (EXCEPT SATURN)»(ref-172-S18951447162000030800000) . 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 (EXCEPT SATURN)»(ref-172-S13169501982000030800000) table. If fuel pressure does not increase to greater than specification, go to step 7 .
17. Check fuel pump electrical circuit. See appropriate FUEL SYSTEM ELECTRICAL CIRCUIT under «NO START DIAGNOSIS»(ref-172-S14051276962000030800000) . 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, fuel feed pipe and fuel pump strainer for restrictions. Check 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 repairs, 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 repairs, go to step 25 .
25. Turn ignition off. Turn A/C system off. On all models except 2.2L and 2.4L, connect Fuel Pressure Gauge (J-34730-1A) to fuel pressure fitting on fuel rail. On 2.2L and 2.4L, 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. On all models, 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 (EXCEPT SATURN)»(ref-172-S13169501982000030800000) 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 (EXCEPT SATURN)

FUEL SYSTEM PRESSURE TEST (SATURN)

Note. Ensure battery is fully charged when performing test.

1. Remove air induction tube. Relieve fuel pressure. See «FUEL SYSTEM PRESSURE RELIEF (SATURN)»(ref-172-S28033099082000030800000) . Install fuel pressure gauge and bleed off any fuel in system into a container. Close fuel pressure gauge shutoff valve.
2. Turn ignition on. Using scan tool, command fuel pump on. Fuel pump should run for about one minute. Allow pressure to stabilize. Record maximum fuel pressure. Fuel pressure reading should be 40-55 psi (2.8-3.9 kg/cm 2 ).
3. Bleed fuel pressure and repeat test at least 2 more times. If during test, fuel pressure drops more than 8 psi (.56 kg/cm 2 ) during a 5 minute period, isolate fuel supply side of fuel system by closing off return side with fuel pressure gauge shutoff valve.
4. Using scan tool, command fuel pump on. Allow fuel pressure to stabilize. Record maximum fuel pressure. If fuel pressure remains stable, replace fuel pressure regulator. If fuel pressure bleeds off more than 8 psi (.56 kg/cm 2 ), check fuel inlet line and injectors for leaks, and check for faulty fuel pump. Repair as necessary.