Engine Controls - Basic Testing: Diagnosis Oldsmobile Ninety-Eight XI

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. See VACUUM DIAGRAMS article in the ENGINE PERFORMANCE Section to verify routing and connections (if necessary). Inspect air induction system for possible vacuum leaks.

Diagnosis

1. Start engine and bring to operating temperature. Increase engine speed to 2000-2500 RPM and note gauge. Reading should not exceed 1.25 psi (.09 kg/cm 2 ). Exhaust system is restricted if specification is exceeded.
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 (A-3)

Note. Some vehicles are equipped with anti-theft systems (VATS or PASS-Key) which will not allow vehicle to be started if improper starting techniques 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 trouble code in ECM memory.

General Inspection

1. Ensure proper starting procedure is being used.
2. Visually check vacuum hoses for splits, kinks and proper connections, as shown on underhood Vehicle Emission Control Information label. Check ignition wires for cracking, hardness and proper connections at both distributor cap and spark plugs. Ensure each plug wire has less than 12,000 ohms resistance.
3. Remove spark plugs. Check and replace as necessary. Remove distributor cap and check for moisture, dust, cracks, burns and arcing to ground.
4. Try to turn distributor shaft by hand. Drive gear pin may be broken. In very cold temperatures, ensure oil is proper viscosity and not contaminated by gasoline.

1. Ensure proper starting procedure is being used.
2. Visually check vacuum hoses for splits, kinks and proper connections, as shown on underhood Vehicle Emission Control Information label. Check ignition wires for cracking, hardness and proper connections at both distributor cap and spark plugs.
3. Remove spark plugs. Check and replace as necessary. Remove distributor cap and check for moisture, dust, cracks, burns and arcing to ground.
4. Try to turn distributor shaft by hand. Drive gear pin may be broken. In very cold temperatures, ensure oil is proper viscosity and not contaminated with gasoline.

1. Ensure proper starting procedure is being used.
2. Visually check vacuum hoses for splits, kinks and proper connections, as shown on underhood Vehicle Emission Control Information label. Check ignition wires for cracking, hardness and proper connections at both distributor cap and spark plugs.
3. Remove spark plugs. Check and replace as necessary. Remove distributor cap and check for moisture, dust, cracks, burns and arcing to ground through coil mounting screws or rotor.
4. Try to turn distributor shaft by hand. Drive gear pin may be broken. 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.
2. Check ignition wires for cracking, hardness and proper connections at both coil pack and spark plugs. In very cold temperatures, ensure oil is proper viscosity and not contaminated with gasoline.

1. Ensure proper starting procedure is being used.
2. 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.
3. Remove spark plugs. Check and replace as necessary.
4. In very cold temperatures, check oil is proper viscosity and not contaminated with gasoline.

1. Ensure proper starting procedure is being used.
2. 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.
3. In very cold temperatures, check 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 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.

Scheme 8

Scheme 9

1. Check fuel pump/injector (F/P INJ) fuse. Scan TPS signal. If scan voltage is not less than 2.5 volts, see Code 21 chart in TESTS W/CODES article in the ENGINE PERFORMANCE Section. Scan CTS temperature. If scan temperature is not -30°C to 130°C, see Code 14 or 15 chart in TESTS W/CODES article in the ENGINE PERFORMANCE Section. Scan 2X reference pulse or RPM while cranking engine. If reference pulses are not displayed and RPM indicates zero, go to step 14).
2. Disconnect 3-wire injector harness connector and connect test light between Gray and Dark Blue wires on ECM side of harness. (Scheme 8)or (Scheme 9). Crank engine and observe test light. Connect test light between Gray and Dark Green wires on ECM side of injector harness. Crank engine. If light flashes during both tests, go to next step. If neither light flashes during injector harness tests, go to step 8). If light flashes only on one wire, go to step 12). If light was on steady on one or both wires, go to step 13).
3. With DVOM on 200-ohm scale, measure resistance between injector harness Gray and Dark Blue wires on injector side of harness. Measure resistance between injector harness Gray and Dark Green wires on injector side of harness. Measured resistance during both tests should be about.9-1.1 ohms. If resistance is within specification, go to step 5).
4. If resistance is not within specification for both measurements, remove crankcase ventilation liquid/vapor separator to gain access to injector connectors. Disconnect injector for circuit which was not within specification. (Scheme 8)or (Scheme 9). With DVOM on 200-ohm scale, injector resistance should be about 1.9-2.1 ohms. If resistance is not correct, replace injector(s) with incorrect resistance. If injectors are within specification, repair open, short or poor connection in injector harness.
5. Temporarily remove IDI assembly and install spark plug Jumper Wires (J-36012). Remove test light from injector harness. Check for adequate spark with Spark Tester (ST-125). While cranking engine, check for spark on 2 adjacent plug wires (1-2 or 3-4, not 2-3). Leave matching plug wire connected while checking for spark. If spark jumps tester on both plug wires, check fuel system pressure and capacity.
6. Turn ignition off. Disconnect plug wires, and remove coil housing. Disconnect coil harness connector at module, and install a test light between module terminal "A" and control terminal for coil which did not spark. (Scheme 8)or (Scheme 9).
7. Crank engine and note test light. If test light blinks at both test terminals, repair faulty harness, poor connection or replace faulty coil. If test light did not blink on both terminals, repair module connections or replace faulty module.
8. If test light did not flash on either test in step 2), remove test light from injector harness. Probe Gray wire of ECM side of injector harness with a test light connected to ground. Turn ignition off for 10 seconds. Turn ignition on. Test light should be on for at least 2-3 seconds. If light is on, go to step 14). If test light is not on, probe fuel pump test connector (Gray wire located in left rear corner of engine compartment) with test light connected to ground. Turn ignition off for 10 seconds. Turn ignition on. Test light should be on for at least 2-3 seconds.
9. If test light is on, repair open in injector harness power supply (Gray) wire. If test light is not on, check fuel pump/injector (F/P INJ) fuse. If fuse is blown, replace fuse. If fuse blows again, repair short to ground in fuel pump power supply circuit. If fuse is okay, turn ignition off. Disconnect fuel pump relay connector, and probe Dark Green/White wire of fuel pump relay (located at center of firewall in engine compartment) using test light connected to battery voltage.
10. Turn ignition on and note test light. If test light is not on, go to next step. If test light is on for 2-3 seconds, check fuel pump relay, relay power supply circuit and circuit between relay and fuel pump test connector and injector harness/fuel pump splice. If fuel pump relay is faulty, oil pressure switch should have energized fuel pump and injectors after extended cranking. Check oil pressure switch also.
11. If test light is not on, backprobe terminal BA11 at ECM with test light to battery voltage. Turn ignition on. If test light is on for 2-3 seconds, repair open in Dark Green/White wire between ECM and fuel pump relay. If test light is not on, problem is poor ECM connection or faulty ECM. Also, check ECM "ignition on" (battery voltage) signal to ECM terminal BA6, as this is the signal the ECM uses to initiate fuel pump relay 2-3 second enable.
12. If test light did not flash during one injector harness test, check/repair open injector drive circuit wire (Dark Blue or Dark Green) on circuit which flash did not occur. If drive circuits are okay, check for open in peak and hold jumper circuits at ECM (BD5, BD6, BC13 and BC15) or poor connection at ECM connector. If peak and hold jumpers and connections are okay, ECM is faulty.
13. If light was on steady on one or both harness tests, check/repair injector drive circuit wire (Dark Blue or Dark Green) which had steady light for short to ground. If circuit is not shorted to ground, ECM is faulty.
14. If no 2X pulses exist, or no RPM is scanned during cranking, turn ignition off. Disconnect 11-pin connector at module. Turn ignition on and connect test light between terminals "K" and "L" at harness. If test light is not on, repair open in module ground or power supply circuit.
15. If test light is on, install injector test light in any injector harness connector. Connect a test light to battery voltage and repeatedly touch to IDI module terminal "H". Injector test light should flash. If test light flashes, go to next step. If test light does not flash, check injector drive circuits for open or short to voltage. Repair as necessary. If drive circuits are okay, check for open of short to ground in 2X reference pulse circuit between ECM and ignition module terminal "H", or poor connection at ECM terminal BD8. If 2X circuit and ECM connection are okay, ECM is faulty.
16. Connect DVOM between terminals "B" and "C" of IDI module harness connector. Place DVOM on 2-volt AC scale. Crank engine and note voltage. Voltmeter should read greater than 20mV. If voltage is correct, replace IDI module. If voltage is not correct, remove crankshaft sensor from block. Measure sensor resistance. Resistance should be 500-900 ohms. Place a flat piece of metal on tip of sensor to verify sensor is still magnetized. Inspect sensor harness. Repair or replace as necessary.

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.

Note. C(3)I ignition system on 3.8L engines may use one of 2 coil pack types. On type I ignition coil pack, 3 twin tower coils are combined into a single coil pack. Coil pack is mounted directly over the C(3)I ignition module. Each coil provides the spark for 2 simultaneously paired spark plugs. All 3 coils must be replaced as a unit. On type II ignition coil pack, 3 separate twin tower coils are independently mounted over the C(3)I ignition module. Each coil provides the spark for 2 simultaneously paired spark plugs. Each coil can be replaced separately.

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.

DIAGNOSTIC CIRCUIT CHECK (EXCEPT PFI CADILLAC)

Note. On PFI Cadillac vehicles, see appropriate TESTS W/CODES article in the ENGINE PERFORMANCE Section.

The Diagnostic Circuit Check determines

1. If SERVICE ENGINE SOON light works.
2. If ECM is operating and can recognize a fault.
3. If any codes are stored.

After performing procedures in PRELIMINARY INSPECTION & ADJUSTMENTS, BASIC FUEL SYSTEM CHECKS and BASIC IGNITION SYSTEM CHECKS, this is the starting point for utilizing the self-diagnostic system for determining computer-related problems. (Scheme 10)and (Scheme 11). After performing necessary tests as described in the diagnostic circuit check, if no codes are indicated and driveability problems still exist, see TESTS W/O CODES article in the ENGINE PERFORMANCE Section and SCAN TESTER USAGE in TESTS W/CODES article in the ENGINE PERFORMANCE Section.

1. Check operation of SERVICE ENGINE SOON light. Turn ignition on with engine off. SERVICE ENGINE SOON light should be on steady. If light illuminates and stays on steady, go to next step. If light does not illuminate, go to A1, SERVICE ENGINE SOON LIGHT INOPERATIVE. If light flashes, go to step 3).
2. Grounding the ALDL test terminal "B" at this time should cause SERVICE ENGINE SOON light to flash a Code 12, followed by any codes stored in ECM memory. see scheme 29 Light going from bright to dim is not considered a code. If light dims or remains on and does not flash Code 12, see A2, SERVICE ENGINE SOON LIGHT ON STEADY OR WON'T FLASH CODE 12. NOTE: On some models, as long as a 30-second pause may occur between code flashes. This is normal and does not indicate necessary component replacement.
3. If light begins to flash as soon as ignition is turned on, check for a short to ground on the diagnostic test terminal wire between ALDL terminal "B" and ECM terminal No. 5. If circuit is okay, replace ECM.

Scheme 10

Diagnostic Circuit Check & Work Flow. Scheme 11