Engine Control System - 1.8L (Lnk) - Troubleshooting: Diagnosis Pontiac Vibe I рестайлинг

Circuit Description

There should always be a steady malfunction indicator lamp (MIL) when the ignition switch is in the ON position and the engine is not running. System voltage is applied to the indicator bulb and the powertrain control module (PCM) provides a path to ground. Once the engine starts, the PCM turns the OFF the MIL. When an engine control system malfunction occurs, the PCM turns ON the MIL and a diagnostic trouble code is stored in memory.

Diagnostic Aids

An intermittent malfunction may be caused by a faulty electrical connection in the MIL circuit. Refer to Intermittent Conditions .

There should be a steady malfunction indicator lamp (MIL) when the ignition is ON, prior to starting the engine. Battery ignition voltage is supplied to the MIL. The powertrain control module (PCM) will turn the MIL ON by grounding the control circuit at the PCM. A steady MIL with the engine running suggests a short to ground in the MIL control circuit, or a diagnostic trouble code (DTC) is stored.

Check for the following conditions

1. Check for a shorted MIL control circuit between the PCM and the instrument panel cluster (IPC) assembly.
2. A shorted IPC assembly board may cause the MIL to stay ON.

An intermittent malfunction may be caused by a faulty electrical connection. Refer to Intermittent Conditions .

Inspect for any of the following conditions

1. Insufficient fuel can cause a no start condition. Thoroughly inspect the fuel delivery system for sufficient fuel volume to the fuel injectors. Inspect the fuel supply components for partial blockage or restrictions.
2. Fuel injectors with partially blocked and restricted nozzles, or a malfunctioning solenoid, can cause a no start condition. Refer to «Fuel Injector Balance Test with Special Tool»(ref-200108-S15816934182005102000000) and «Fuel Injector Coil Test - Engine Coolant Temperature (ECT) Between 10-35 Degrees C (50-95 Degrees F)»(ref-200108-S01298020412005102000000) .
3. There may be fuel spray at the fuel injectors and the indicated fuel pressure may be correct, yet there may not be enough fuel to start the engine. If the fuel injectors and the injector circuit are OK, and fuel spray is detected, the fuel injector ON time may be inadequate. If the powertrain control module (PCM) receives incorrect inputs from the various information sensors, the fuel delivered by the fuel injectors may be inadequate to start the engine. Check all the engine data parameters with a scan tool and compare the values indicated with the expected values or the values from a known good vehicle.
4. Check the crankshaft position (CKP) sensor engine reference signal with a scan tool. Observe the Engine Speed parameter while cranking the engine. The scan tool should indicate a steady 200-300 RPM while cranking. If erratic values, such as sudden spikes in the engine speed are displayed, the engine reference signal is not stable enough for the engine to start and run properly.
5. An intermittent condition of cranks but will not start or the engine quits while running can be caused by a PCM shutdown. There will be no fuel, spark, or data communications during a PCM shutdown. A short to ground in the 5-volt reference circuit of the engine data sensors will cause a PCM shutdown. When the short to ground is absent, the PCM will operate normally with no DTCs stored. Test for a shorted throttle position (TP) or fuel tank pressure (FTP) sensor, or shorted sensor wiring.
6. Inspect the engine electrical grounds G104, G105, and G201 if the engine has no spark and no fuel injector pulse with no DTCs. Refer to «Power Distribution Schematics»(ref-200048-S13316999942005102000000) and «Ground Distribution Schematics»(ref-200048-S04948991492005102000000) in Wiring Systems.
7. If the engine almost starts and then stalls, check for an open in the ground circuits of the CKP sensor and the camshaft position (CMP) sensor.
8. Water or foreign material in the fuel can cause a no start or engine will not stay running condition. During freezing weather water can freeze inside the fuel system. The engine may start after 30 minutes in a heated repair shop. The malfunction may not recur until parked overnight in freezing temperatures. Extreme weather conditions can cause contaminated fuel to prevent the vehicle from starting.
9. A vehicle that starts and runs after being brought to the repair shop for a no start complaint, may have an ignition system that is susceptible to moisture. Spray water on the ignition system components and the wiring in order to check for an engine starting or will not stay running concern.

An intermittent malfunction may be caused by fault in any of the critical information or component electrical circuits. Inspect the wiring harness and the components for an intermittent condition. Refer to Intermittent Conditions .

Repair any electrical circuit faults that were found. Refer to Wiring Repairs in Wiring Systems.

The ignition relay, also called the EFI relay, provides ignition positive voltage to the control module and other engine control components anytime the ignition is ON. One side of the coil of the EFI relay is always grounded. The other side of the coil receives 12 volts from the powertrain control module (PCM). When the coil is energized, a magnetic field closes the switch side of the relay, supplying power to the following engine components

1. The fuel pump relay, also called the circuit opening relay
2. The heated oxygen sensors (HO2S)
3. The mass air flow (MAF) sensor
4. The evaporative emission (EVAP) control system solenoids and vacuum pump
5. The idle air control (IAC) valve
6. The PCM

Check for any of the following conditions

1. Check the resistance of the EFI relay. There is continuity across terminal 1 and terminal 2. The resistance across terminal 5 and terminal 3 is infinite.
2. The EFI relay electrical contacts may be pitted or sticking. Replace the EFI relay if tapping gently on the relay or wiggling the relay causes a change in the relay's operation.
3. The performance of the EFI relay may be affected by temperature. Check the EFI relay after sitting outside overnight and after running the engine 30 minutes.
4. If the EFI fuse opens during cranking, check for a shorted fuel pump/circuit. The EFI relay supplies current to the circuit opening relay that supplies power the fuel pump. The circuit opening relay is energized during cranking and when reference pulses are detected by the PCM.

An intermittent malfunction may be caused by a fault in the EFI relay electrical circuit. Inspect the wiring harness and components for an intermittent condition. Refer to Intermittent Conditions .

Use the following relay cavity table in order to locate the correct cavities to probe during diagnosis. The table layout corresponds to the cavity layout of the relay block.

Ignition Relay Diagnosis

The circuit opening relay provides ignition positive voltage to the fuel pump. The circuit opening relay is controlled by the powertrain control module (PCM) and receives ignition positive voltage from the EFI relay. The PCM monitors the crank signal circuit for voltage when the ignition switch is in the START (engine cranking) position. When the crank signal circuit indicates the engine is cranking the PCM energizes the circuit opening relay. The PCM also energizes the circuit opening relay whenever reference pulses from the crankcase position (CKP) sensor circuit are detected. If the crank signal circuit does NOT indicate the engine is cranking the PCM will energize the circuit opening relay based only upon reference pulses.

Check for any of the following conditions

1. The resistance of the circuit opening relay - The resistance across terminal 2 and terminal 3 is 85-95 ohms at 20°C (68°F). The resistance across terminal 1 and terminal 4 is infinite.
2. The circuit opening relays electrical contacts may be pitted or sticking. Replace the relay if tapping gently on the relay or wiggling the relay causes a change in the relays operation.
3. The performance of the circuit opening relay may be affected by temperature. Check the relay after sitting outside overnight and after running the engine 30 minutes.

An intermittent malfunction may be caused by a fault in the fuel pump electrical circuit. Refer to Intermittent Conditions .

Use the following relay cavity table in order to locate the correct cavities to probe during diagnosis. The table layout corresponds to the cavity layout of the relay block.

Fuel Pump Electrical Circuit Diagnosis

The sequential multiport fuel injection (SFI) system is controlled by the powertrain control module (PCM). The PCM energizes the solenoid coil of each fuel injector individually by completing the electrical circuit to ground. When energized the fuel injector solenoid operates the solenoid plunger, allowing pressurized fuel to be injected into the intake port of the cylinder. The fuel pump will pressurize the fuel rail and the fuel injectors as long as the engine is cranking and the PCM is receiving the ignition system reference pulses.

Check for any of the following conditions

1. Water, contaminated fuel, or inferior quality fuel can cause a no start or hard start condition, even though the fuel injectors and circuitry are OK.
2. Check for a faulty spray pattern from the fuel injector nozzle if both the fuel injector solenoid and the fuel injector circuit are OK.
3. There may be fuel spray at the fuel injectors and the indicated fuel pressure may be correct, yet there may not be enough fuel to start the engine. If the fuel injectors and the injectors' circuit are OK, and fuel spray is detected, some fuel injector nozzles may be partly blocked or restricted. If the PCM receives incorrect inputs from the various information sensors the fuel delivered by the fuel injectors may be inadequate to start the engine. Check all engine data parameters with a scan tool and compare the values indicated with expected values or values on a known good vehicle.
4. The normal fuel injector resistance is 13.4-14.4 ohms at 20°C (68°F).
5. If you were sent here by a DTC P0300 and all the injectors checked OK, the Misfire Current Cylinder or Misfire Graphic information on a scan tool can be used to determine which injector circuit should be examined more closely.

An intermittent malfunction may be caused by a fault in the fuel injector electrical circuit. Inspect the wiring harness and the components for an intermittent condition. Refer to Intermittent Conditions .

Fuel Tank Leak Test

1. Drain the fuel tank. Refer to «Fuel Tank Draining Procedure»(ref-200095-S17269205012005102000000) .
2. Remove the fuel tank. Refer to «Fuel Tank Replacement»(ref-200095-S01850779682005102000000) .
3. Plug the fuel feed hose, the fuel limiter vent valve hose, and the fuel tank vent valve hose on the fuel tank.
4. Plug the fuel filler neck opening.
5. Connect a piece of the hose to the breather hose nipple on the fuel tank and secure the hose with one clamp.
6. Submerge the fuel tank in water or apply a soapy solution to the outside of the tank.
7. Apply 7-15 kPa (1-2 psi) air pressure to the breather hose.
8. Air bubbles appearing from the fuel tank indicate a leak.
9. Replace the fuel tank if the tank is leaking.

Alcohol/Contaminants-in-Fuel Diagnosis

The concentration of alcohol-in-fuel can be detrimental to the fuel system. Higher than recommended alcohol-in-fuel concentrations may cause driveability problems such as hesitation, lack of power, stall, no start, etc. High concentrations may also cause corrosion of the fuel system components and subsequent fuel filter plugging as well as deterioration of the rubber and the plastic components.

Commercial automotive fuel can contain alcohol in various types and levels of concentration. Some forms of alcohol are more detrimental to the fuel system components than others. If an excessive amount of alcohol-in-fuel is suspected as the cause of a driveability problem, the following procedure can be used to detect its presence. This procedure uses water to extract the alcohol from the fuel. The specific type of alcohol contamination cannot be determined from this test.

Testing Procedure

The fuel sample should be drawn from the bottom of the fuel tank, because any water present in the tank will be concentrated there. The fuel sample should be bright and clear. If the sample appears to be cloudy or contaminated with the water as indicated by a water layer at the bottom of the sample, this procedure should not be used. The fuel system should be cleaned. Refer to Fuel System Cleaning .

1. Using a 100 ml cylinder with 1 ml graduation marks, fill with the fuel sample to the 90 ml mark.
2. Add 10 ml of the water to bring the total fluid volume to 100 ml and install a stopper.
3. Shake vigorously for 10-15 seconds.
4. Carefully loosen the stopper to release the pressure.
5. Close the stopper and shake the cylinder vigorously again for 10-15 seconds.
6. Put the graduated cylinder on a level surface for approximately 5 minutes to allow adequate time for the liquid to separate.

If there is alcohol present in the fuel, the volume of the lower layer, which will now contain both alcohol and water, will be more than 10 ml.

For example, if the volume of the lower layer is increased to 15 ml, this will indicate that there is at least 5 percent alcohol in the fuel. The actual amount of the alcohol may be somewhat more because this procedure does not extract all of the alcohol from the fuel.

The powertrain control module (PCM) controls the idle air control (IAC) valve in order to regulate the air flow through the idle air bypass passage. The amount of air flowing through the idle air bypass passage determines the idle speed. The PCM directs the IAC valve according to changes in engine load. A stalling or poor idle concern could be caused by an IAC valve that is not operating properly.

Any condition that can affect engine performance at idle, can affect the performance of the IAC system. A careful visual and/or physical inspection of the engine is necessary when the scan tool indicates that the engine speed or the IAC Motor Command readings are out of range.

An intermittent IAC system concern may be caused by poor electrical connections in the IAC valve circuits. Thoroughly check any circuitry that is suspected of causing an intermittent condition. Refer to Intermittent Conditions .

Auxiliary Intake Air Control Solenoid Inspection with Scan Tool

The auxiliary intake air control solenoid is operated by the powertrain control module (PCM). The PCM supplies a ground path to the solenoid control circuit using an internal solid state device called a driver. When the PCM commands the solenoid ON, the voltage on the control circuit should be near zero or low. When the PCM commands the solenoid OFF, the voltage on the control circuit should be near battery voltage or high. When the solenoid is energized, manifold vacuum is applied to the vacuum motor and the auxiliary inlet air duct door is closed.

Auxiliary Intake Air Control Solenoid Inspection w/o Scan Tool

The auxiliary intake air control solenoid is operated by the powertrain control module (PCM). The PCM supplies a ground path to the solenoid control circuit using an internal solid state device called a driver. When the PCM commands the solenoid ON, the voltage on the control circuit should be near zero or low. When the PCM commands the solenoid OFF, the voltage on the control circuit should be near battery voltage or high. When the solenoid is energized, manifold vacuum is applied to the vacuum motor and the auxiliary inlet air duct door is closed.

1. Disconnect the electrical connector of the intake air control solenoid.
2. Use a DMM in order the measure the solenoid resistance value. Specification: The resistance should be between 37-44 ohms at 20°C (68°F).
3. Replace the solenoid if the resistance is not within the specified range. Refer to «Auxiliary Intake Air Control Solenoid Replacement»(ref-200095-S21576324592005102000000) .
4. Use a DMM in order the check for continuity between each solenoid terminal and the solenoid housing. Specification: The DMM has to read infinite (OL).
5. Replace the intake air control solenoid if the resistance is not within specification. A shorted solenoid may cause damage to the PCM.
6. Blow air through the inboard port of the intake air control solenoid. Air has to flow freely through the vent port and NOT out of the outboard port.
7. Replace the solenoid if either of the following conditions is observed. Refer to «Auxiliary Intake Air Control Solenoid Replacement»(ref-200095-S21576324592005102000000) . Air flows from the inboard port out through the outboard port. Air does not flow from the inboard port out through the vent port.
8. Apply battery voltage across the solenoid terminals.
9. Blow air through the inboard port of the solenoid. Air should flow through the solenoid and out of the outboard port.
10. Replace the solenoid if the solenoid fails any of the tests. Refer to «Auxiliary Intake Air Control Solenoid Replacement»(ref-200095-S21576324592005102000000) .
11. Connect the electrical connector of the intake air control solenoid.
12. Start the engine.
13. Inspect that the intake air control solenoid is ON.
14. If the solenoid is not energized, disconnect the solenoid electrical connector and connect a test lamp across the terminals of the solenoid circuit.
15. If the test lamp illuminated, replace the solenoid. Refer to «Auxiliary Intake Air Control Solenoid Replacement»(ref-200095-S21576324592005102000000) .
16. If the test lamp did not illuminate, inspect for the following conditions: Inspect for an open in the ignition positive voltage supply to the solenoid. Inspect for an open or a short to voltage in the solenoid control circuit.
17. Repair any electrical circuit conditions as necessary. Refer to «Wiring Repairs»(ref-200048-S12226828122005102000000) in Wiring Systems.
18. If you did not find and repair an electrical condition, replace the PCM. Refer to «Control Module References»(ref-200102-S05820283132005102000000) in Computer/Integrating Systems for replacement, setup, and programming.

The powertrain control module (PCM) receives an idle-up signal when certain engine electrical loads or engine accessory loads are present. The PCM increases the flow of air through the idle (bypass) air passage of the idle air control (IAC) valve when receiving an idle-up signal. The additional air flowing through the idle air passage causes an increase in the idle speed. The idle speed is increased in order to accommodate the increased engine electrical or engine accessory load. The PCM monitors the following systems for idle-up signals

1. The electric rear window defogger
2. The exterior lighting system
3. The A/C system-When A/C is selected from the HVAC control unit the PCM receives a 12 volt signal. Once the PCM is aware of the request for A/C, the PCM determines whether engagement of the A/C compressor clutch is OK. In order to enable compressor clutch engagement the PCM provides a ground for the control circuit of the A/C compressor clutch relay. The PCM also increases engine idle speed in order to prevent a rough idle or a stalling condition when the A/C compressor is engaged.
4. The power steering system - The power steering pressure (PSP) switch is normally open to ground. Turning the steering wheel increases the power steering oil pressure. Increased power steering oil pressure puts an additional load on the engine that may be noticeable at idle. The PSP switch closes when the power steering system oil pressure is high enough to cause an undesirable idle condition. The voltage signal from the PSP switch to the PCM indicates less than one volt when the PSP switch is closed. The voltage signal is near battery voltage when the PSP switch is open.

Check for any of the following conditions

1. The High Electrical Load parameter on the scan tool can indicate if the PCM has received the rear defogger or parking lamps ON signal. The scan tool should indicate Yes when the rear defogger or parking lamps are turned ON and engine speed should increase slightly. Check for a malfunction in the IAC system or a short to ground in the Diagnostic Request circuit if the engine speed does not increase.
2. A malfunctioning rear defogger or parking lamp (taillight) circuit may cause erratic electrical load idle-up circuit performance. Check for a properly operating rear defogger or taillight system.
3. A PSP switch that does not close, or loss of ground at the PSP switch may cause the engine to stall when the power steering loads are high.
4. The scan tool will display A/C Request Signal YES when A/C is selected and the HVAC blower switch is ON at any speed. The scan tool will display A/C Clutch ON whenever the PCM is allowing A/C compressor engagement. Therefore the scan tool will also display A/C Clutch ON when any defrost mode is selected.

An intermittent malfunction may be caused by a fault in any one of the idle-up signal circuits. Inspect the wiring harness and components for an intermittent condition. Refer to Intermittent Conditions .

EVAP Canister Inspection

Tools Required

1. J 23738-A Hand Vacuum Pump. See «Special Tools»(ref-200095-S21125557472005102000000) .
2. J 41413-300 EVAP Cap and Plug Kit.

1. Remove the evaporative emission (EVAP) canister. Refer to «Evaporative Emission (EVAP) Canister Replacement»(ref-200095-S13047420872005102000000) .
2. Visually inspect the EVAP canister, especially at the arrows, for any cracks or damage.
3. Use the J 41413-300 or an equivalent in order to block the purge port (2) closed.
4. Blow air with a pressure of 1.7 kPa (0.5 in Hg/0.25 psi) into the ORVR vent port (1).
5. Verify that air flows out of inlet air port (3).
6. Block the on-board refueling vapor recovery (ORVR) vent port (3) closed.
7. Connect the J 23738-A or an equivalent to the purge port (1).
8. Apply a vacuum of 0.85 kPa (0.25 in Hg/0.18 psi) into the purge port (1).
9. Verify that air is drawn into the air inlet port (2).
10. Block the air inlet port (4) closed.
11. Block the purge port (3) closed.
12. Remove the small vacuum hose between the fill limiter vent valve (FLVV) port (1) and the EVAP vacuum leak pump port (2).
13. Block the vacuum leak pump port (2) closed.
14. Apply a pressure of 19.6 kPa (5.8 in Hg/2.81 psi) to the ORVR vent port (5).
15. Verify that the pressure holds and does not leak out the small vacuum port (1).
16. Replace the EVAP canister and EVAP vacuum leak pump if any of the inspections or tests are failed. Refer to «Evaporative Emission (EVAP) Canister Replacement»(ref-200095-S13047420872005102000000) .

EVAP Canister Vacuum Leak Pump Assembly Inspection

Evaporative Emission (EVAP) Control System Diagnosis

1. Remove the EVAP canister vacuum leak pump. Refer to «Evaporative Emission (EVAP) System Vacuum Leak Pump Replacement»(ref-200095-S12249816282005102000000) .
2. Use a DMM in order to measure the resistance of the EVAP vent solenoid that is located in the EVAP vacuum leak pump assembly.
3. Connect the DMM to the ignition voltage terminal and the solenoid control terminal. Refer to the vacuum pump terminal identification table above. Measure: The EVAP canister vent valve resistance should be 25-30 ohms at 20°C (68°F).
4. Replace the EVAP vacuum leak pump assembly if the resistance is not within the specified range. The solenoid can damage the powertrain control module (PCM) if the resistance value is less than 25 ohms.
5. Check the PCM and replace, if necessary. Refer to «Control Module References»(ref-200102-S05820283132005102000000) in Computer/Integrating Systems for replacement, setup, and programming.
6. Blow air into the air inlet port. The air should flow through the assembly and out of both ports.
7. Apply battery voltage to the ignition voltage terminal and the solenoid control terminal. Refer to the vacuum pump terminal identification table above.
8. Blow air into the air inlet port. The air should flow only through small port and NOT the large canister port.
9. Replace the EVAP vacuum leak pump assembly if the pump failed either test. Refer to «Evaporative Emission (EVAP) System Vacuum Leak Pump Replacement»(ref-200095-S12249816282005102000000) .

EVAP Canister Purge Valve Inspection

1. Remove the EVAP canister purge valve. Refer to «Evaporative Emission (EVAP) Canister Purge Solenoid Valve Replacement»(ref-200095-S05667229812005102000000) .
2. Use a DMM in order to measure the resistance of the EVAP canister purge valve. Measure: The EVAP canister purge valve resistance should be 26-30 ohms at 20°C (68°F).
3. Replace the EVAP canister purge valve if the resistance is not within the specified range. The solenoid can damage the powertrain control module (PCM) if the resistance value is less than 26 ohms.
4. Check the PCM and replace, if necessary. Refer to «Control Module References»(ref-200102-S05820283132005102000000) in Computer/Integrating Systems for replacement, setup, and programming.
5. Blow air into one of the ports. The air should NOT flow through the opposite port.
6. Apply battery voltage across the terminals of the EVAP canister purge valve.
7. Blow air into the one port. The air should flow easily to the opposite port.
8. Replace the EVAP canister purge valve if the valve failed either test. Refer to «Evaporative Emission (EVAP) Canister Purge Solenoid Valve Replacement»(ref-200095-S05667229812005102000000) .

Each engine cylinder has a dedicated ignition coil assembly. The ignition coil assembly contains the ignition module circuitry. The power distribution circuit supplies system voltage to each coil assembly when the ignition switch is in the ON or START positions. Each coil assembly regulates current flow through the primary coil windings, creating a magnetic field. The powertrain control module (PCM) signals each coil assembly to supply a spark in a cylinder through a trigger circuit. Each assembly does so by opening the primary circuit coil, inducing a high voltage in the secondary circuit coil. The high voltage in the secondary circuit grounds by arcing at the spark plug. This event creates a pulse on the fail safe circuit that the PCM recognizes as a confirmation of spark.

Check for any of the following conditions

1. Any circuit malfunction between the ignition coil assembly and the PCM should set a fail safe circuit DTC P0351, P0352, P0353, or P03545.
2. Check the crankshaft position (CKP) sensor engine reference signal with a scan tool. Observe the Engine Speed parameter while cranking the engine. The scan tool should indicate a steady 200-300 RPM while cranking. If erratic values, such as sudden spikes in the engine speed, are displayed, the engine reference signal is not stable enough for dependable ignition system operation.
3. An ignition system that tests OK after sitting may be susceptible to moisture. Spray water on the ignition system components and wiring in order to check for an intermittent failure.

Crankcase Ventilation System Inspection/Diagnosis

1. Remove the positive crankcase ventilation (PCV) valve. Refer to «Positive Crankcase Ventilation Valve Replacement»(ref-200095-S40843537922005102000000) .
2. Blow air into the cylinder head side of the PCV valve.
3. Check that air passes through the PCV valve easily.
4. Blow air into the intake manifold side of the PCV valve.
5. Check that air passes through the PCV valve with high resistances.
6. If the PCV valve fails either test, replace the PCV valve. Refer to «Positive Crankcase Ventilation Valve Replacement»(ref-200095-S40843537922005102000000) .
7. Inspect the PCV hose for damage, restrictions, or leaks. Replace the hose as necessary.
8. Inspect all PCV system passages and connections for leaks or restrictions. Repair as necessary.

The I/M System Status display provides an indication of when the control module has completed the required tests. This does not necessarily mean that the test has passed, only that a decision was made. If the diagnostic fails, a DTC will indicate the failure. If a failure indication is present for a DTC associated with one of the I/M regulated systems, the DTC may prevent other required tests from running. For example, a DTC for the control circuit of the relay controlling an AIR pump may not be listed in the Inspection/Maintenance System DTC Table because the DTC is a continuous test. If this DTC is set, the Active Tests for the AIR system may not run.

The I/M System Status information may be useful for a technician to determine if diagnostics have run when verifying repairs.

Conditions for Running

1. The barometric pressure (BARO) is more than 75 kPa (22 in Hg).
2. The engine coolant temperature (ECT) is below 24°C (75°F).
3. The battery voltage is between 10.5-16 volts.
4. The fuel level is between 1/4 and 3/4.

Rough road conditions may prevent some of the tests from running. Extreme high or low ambient temperatures may prevent tests such as heated oxygen (HO2S) heater and evaporative emission (EVAP) System from initiating. If a step is interrupted before completion, perform the remaining portion of the set procedures. Any portion of the set procedure that requires the engine at operating temperature may be repeated. This allows most of the diagnostics to run and the remaining tests can be performed using the individual System Set Procedures.

The scan tool can be used to monitor each of the I/M System Status indicators during the I/M Complete System Set Procedure. When all of the indicators for a test step have updated to YES, testing can move on to the next step even if the remaining portion of the test is not complete. For example, step 3 is designed to run the Catalyst Test. The procedure instructs the technician to operate the vehicle in the enable conditions for 6 minutes. If the test updates to YES within 4 minutes, it is not necessary to continue with the enable conditions and testing can advance to the next step.

Inspection/Maintenance (I/M) System DTC Table

Inspection/Maintenance (I/M) System DTC Table

1. The barometric pressure (BARO) is more than 75 kPa.
2. The engine coolant temperature (ECT) is at least 70°C (158°F).
3. Battery voltage is between 10.5-16 volts.

If the status does not update, the test outlined in this procedure can be repeated until the I/M System Status updates to YES.

The I/M System Status does not indicate whether the test has passed or failed, only that a decision was made. When all of the diagnostics for a specific system have run and passed, the I/M System Status will update to YES. If a test for a specific system has failed, the I/M System Status will update to YES, indicating a determination was made, even if all of the required tests have not run. When a failure occurs, the Emission Related DTC portion of the I/M System Status display will indicate the malfunction indicator lamp (MIL) is requested. The I/M System Status also registers the number of diagnostic trouble codes (DTCs).

The first failure of a type B DTC does not constitute a final determination of pass or fail, and will not update the I/M System Status to YES. A second trip is required, and all the conditions to run must be met in order for the test to run again. These conditions may include a partial to complete engine cool down.

The I/M System Status will update only when an emission related DTC fails the second time, or when all of the tests pass.

If there is an impending failure, the system may require more time to run the diagnostic than was allotted in the set procedure. If the test does not run after numerous attempts and no DTC is set, review the appropriate scan tool data list and the service information for an indication of why the test does not complete. Some tests may abort due to changes in the conditions while the test is running. For example, changes in engine load, such as a cooling fan or an A/C compressor clutch turning ON, may cause the test to abort.

If a diagnostic test is difficult to run, maintain necessary enable conditions until the system status updates to YES.

Scan Tool Service Bay Test equipped vehicle

1. The intake air temperature (IAT) is more than 5°C (40°F).
2. The engine coolant temperature (ECT) is more than 5°C (40°F).
3. The fuel level is between 25-90 percent.
4. The battery voltage is between 10.5-18 volts.

Non Scan Tool Service Bay Test equipped vehicles

1. The BARO pressure indicates that the altitude is less than 2,400 meters (8,000 feet).
2. The IAT is between 5-35°C (40-95°F) at engine start.
3. The ECT is between 5-35°C (40-95°F) at engine start.
4. The fuel level is between 25-90 percent.
5. The battery voltage is between 10.5-18 volts.
6. The vehicle is driven for at least 15 minutes.

Extreme high or low ambient temperatures may prevent the EVAP System Tests from initiating. Performing a visual inspection prior to running the EVAP System Set Procedure may prevent having to repeat the test. A loose fuel cap may cause a test to abort or fail and prevent the I/M System Status from updating. A failed or aborted test will require the vehicle to cool down in order to meet the enable criteria to run another test.

The I/M System Status does not indicate whether the test has passed or failed, only that a decision was made. When all of the diagnostics for a specific system have run and passed, the I/M System Status will update to YES. If a test for a specific system has failed, the I/M System Status will update to YES, indicating a determination was made, even if all of the required tests have not run. When a failure occurs, the Emission Related DTC portion of the I/M System Status display will indicate the malfunction indicator lamp (MIL) is requested. The I/M System Status also registers the number of diagnostic trouble codes (DTCs).

The first failure of a type B DTC does not constitute a final determination of pass or fail, and will not update the I/M System Status to YES. A second trip is required, and all the conditions to run must be met in order for the test to run again. These conditions may include a partial to complete engine cool down.

The I/M System Status will update only when an emission related DTC fails the second time, or when all of the tests pass.

If there is an impending failure, the system may require more time to run the diagnostic than was allotted in the set procedure. If the test does not run after numerous attempts and no DTC is set, review the appropriate scan tool data list and the service information for an indication of why the test does not complete. Some tests may abort due to changes in the conditions while the test is running. For example, changes in engine load, such as a cooling fan or an A/C compressor clutch turning ON, may cause the test to abort.

If a diagnostic test is difficult to run, maintain necessary enable conditions until the system status updates to YES.

1. The engine coolant temperature (ECT) is at least 70°C (158°F).
2. The engine is running in Closed Loop fuel control.
3. The battery voltage is between 10.5-16 volts.

If the status does not update, the test outlined in this procedure can be repeated until the I/M System Status updates to YES.

The I/M System Status does not indicate whether the test has passed or failed, only that a decision was made. When all of the diagnostics for a specific system have run and passed, the I/M System Status will update to YES. If a test for a specific system has failed, the I/M System Status will update to YES, indicating a determination was made, even if all of the required tests have not run. When a failure occurs, the Emission Related DTC portion of the I/M System Status display will indicate the malfunction indicator lamp (MIL) is requested. The I/M System Status also registers the number of diagnostic trouble codes (DTCs).

The first failure of a type B DTC does not constitute a final determination of pass or fail, and will not update the I/M System Status to YES. A second trip is required, and all the conditions to run must be met in order for the test to run again. These conditions may include a partial to complete engine cool down.

The I/M System Status will update only when an emission related DTC fails the second time, or when all of the tests pass.

If there is an impending failure, the system may require more time to run the diagnostic than was allotted in the set procedure. If the test does not run after numerous attempts and no DTC is set, review the appropriate scan tool data list and the service information for an indication of why the test does not complete. Some tests may abort due to changes in the conditions while the test is running. For example, changes in engine load, such as a cooling fan or an A/C compressor clutch turning ON, may cause the test to abort.

If a diagnostic test is difficult to run, maintain necessary enable conditions until the system status updates to YES.

1. The engine is running.
2. The battery voltage is between 10.5-16 volts.
3. The test will always initiate after a cold start. The control module considers the engine to be cold if the engine coolant temperature (ECT) is below 24°C (75°F).

The HO2S Heater Tests will normally run within the 2 minutes allotted in the procedure. If there is an indeterminate condition, the test may take up to 8 minutes on some vehicles before a decision of pass or fail is made. If the test does not update within the allotted period of time, continue operation within the enable conditions until the test updates to YES. If the test does not update to YES, it may have failed or aborted due to the loss of enabling conditions. Extremely high ambient temperatures may prevent the HO2S Heater from initiating. The oxygen sensor heaters are operated by the engine control module. The control module has the ability to monitor the current required by the heaters and does this on a continuous basis.

The I/M System Status does not indicate whether the test has passed or failed, only that a decision was made. When all of the diagnostics for a specific system have run and passed, the I/M System Status will update to YES. If a test for a specific system has failed, the I/M System Status will update to YES, indicating a determination was made, even if all of the required tests have not run. When a failure occurs, the Emission Related DTC portion of the I/M System Status display will indicate the malfunction indicator lamp (MIL) is requested. The I/M System Status also registers the number of diagnostic trouble codes (DTCs).

The first failure of a type B DTC does not constitute a final determination of pass or fail, and will not update the I/M System Status to YES. A second trip is required, and all the conditions to run must be met in order for the test to run again. These conditions may include a partial to complete engine cool down.

The I/M System Status will update only when an emission related DTC fails the second time, or when all of the tests pass.

If there is an impending failure, the system may require more time to run the diagnostic than was allotted in the set procedure. If the test does not run after numerous attempts and no DTC is set, review the appropriate scan tool data list and the service information for an indication of why the test does not complete. Some tests may abort due to changes in the conditions while the test is running. For example, changes in engine load, such as a cooling fan or an A/C compressor clutch turning ON, may cause the test to abort.

If a diagnostic test is difficult to run, maintain necessary enable conditions until the system status updates to YES.

Service Bay Test

The Service Bay Tests are included on the scan tool for some systems depending upon vehicle make and model. The service bay tests initiate the operation of certain PCM controlled functions, assisting the technician in system diagnosis.

EVAP Service Bay Test

The EVAP service bay test is designed to enable the PCM to run the on-board EVAP system diagnostic. If the diagnostic detects any system leaks or component failures the PCM stores the appropriate DTC under Last Test Failed. Throughout the diagnostic test sequence the PCM uses the fuel tank pressure (FTP) sensor in order to monitor the vapor pressure in EVAP system. Unexpected changes in EVAP system pressure can indicate the incorrect operation of EVAP system components and detect system leaks.

The EVAP service bay test is an automated sequence of four individual EVAP test events. The following table provides an overview of each event

Service Bay Test

The EVAP service bay test can run up to 10 minutes to run. If the test detects a fault in the first or second event, the test may run less than 2 minutes. When the service bay test is complete, the EVAP I/M System Status updates to YES. In order to perform the EVAP service bay test with the scan tool follow the procedures below

1. Install the scan tool.
2. Turn ON the ignition, with the engine OFF.
3. Ensure that the fuel filler cap is installed securely.
4. Perform the scan tool Clear DTC function.
5. Enable the EVAP Service Bay Test with the scan tool.
6. If the scan tool displays Test in Progress, the service bay test is enabled.
7. If the scan tool displays Test Failed, the test was not enabled. Exit the test screen on the scan tool and turn OFF the ignition for 30 seconds. After 30 seconds turn ON the ignition and enable the test again with the scan tool.
8. DO NOT turn OFF the ignition or select EXIT on the scan tool during the Test in Progress display.
9. WAIT until the scan tool displays Test Complete.
10. Check for DTCs under Last Test Failed with the scan tool.
11. No DTCs stored indicates that the EVAP system diagnostic has passed and no EVAP system faults are present.
12. Any stored DTC indicates that an EVAP system fault exists. Go to the appropriate DTC table and perform the diagnostic procedure as necessary.