Engine Controls (Introduction) -- 2.2L (L61): Other Saturn VUE I

Temperature vs Resistance

Temperature vs Resistance

Altitude vs Barometric Pressure

Altitude vs Barometric Pressure

Emissions Related DTCs

Action Taken When the DTC Sets - Type A

1. The control module illuminates the malfunction indicator lamp (MIL) when the diagnostic runs and fails.
2. The control module records the operating conditions at the time the diagnostic fails. The control module stores this information in the Freeze Frame/Failure Records.

Action Taken When the DTC Sets - Type B

1. The control module illuminates the MIL on the second consecutive ignition cycle that the diagnostic runs and fails.
2. The control module records the operating conditions at the time the diagnostic fails. The first time the diagnostic fails, the control module stores this information in the Failure Records. If the diagnostic reports a failure on the second consecutive ignition cycle, the control module records the operating conditions at the time of the failure. The control module writes the operating conditions to the Freeze Frame and updates the Failure Records.

Conditions for Clearing the MIL/DTC - Type A or Type B

1. The control module turns OFF the MIL after 3 consecutive ignition cycles that the diagnostic runs and does not fail.
2. A current DTC Last Test Failed clears when the diagnostic runs and passes.
3. A history DTC clears after 40 consecutive warm-up cycles, if no failures are reported by this or any other emission related diagnostic.
4. Use a scan tool in order to clear the MIL and the DTC.

Non-Emissions Related DTCs

Action Taken When the DTC Sets - Type C

1. The control module stores the DTC information into memory when the diagnostic runs and fails.
2. The MIL will not illuminate.
3. The control module records the operating conditions at the time the diagnostic fails. The control module stores this information in the Failure Records.
4. The driver information center, if equipped, may display a message.

Action Taken When the DTC Sets - Type D

1. The control module stores the DTC information into memory when the diagnostic runs and fails.
2. The MIL will not illuminate.
3. The control module records the operating conditions at the time the diagnostic fails. The control module stores this information in the Failure Records.

Conditions for Clearing the DTC - Type C or Type D

1. A last test failed, or current DTC, clears when the diagnostic runs and passes.
2. A history DTC clears after 40 consecutive warm-up cycles, if no failures are reported by this or any other non-emission related diagnostic.
3. Use a scan tool in order to clear the DTC.

CKP System Variation Learn Procedure

1. Install a scan tool.
2. Monitor the engine control module (ECM) for DTCs with a scan tool. If other DTCs are set, except DTC P0315, refer to «Diagnostic Trouble Code (DTC) List»(ref-188782-S08542865492005090200000) for the applicable DTC that set.
3. Select the crankshaft position variation learn procedure with a scan tool.
4. The scan tool instructs you to perform the following: Accelerate to wide open throttle (WOT). Release throttle when fuel cutoff occurs. Observe fuel cutoff specifications for applicable engine. Engine should not accelerate beyond calibrated RPM value. Release throttle immediately if value is exceeded. Block drive wheels. Set parking brake. DO NOT apply brake pedal. Cycle ignition from OFF to ON. Apply and hold brake pedal. Start and idle engine. Turn A/C OFF. Vehicle must remain in Park or Neutral. The scan tool monitors certain component signals to determine if all the conditions are met to continue with the procedure. The scan tool only displays the condition that inhibits the procedure. The scan tool monitors the following components: Crankshaft position (CKP) sensors activity-If there is a CKP sensor condition, refer to the applicable DTC that set. Camshaft position (CMP) signal activity-If there is a CMP signal condition, refer to the applicable DTC that set. Engine coolant temperature (ECT) - If the engine coolant temperature is not warm enough, idle the engine until the engine coolant temperature reaches the correct temperature.
5. Enable the crankshaft position system variation learn procedure with the scan tool and perform the following: Accelerate to WOT. Release when fuel cutoff occurs. Test in progress
6. The scan tool displays Learn Status: Learned this ignition. If the scan tool indicates that DTC P0315 ran and passed, the CKP variation learn procedure is complete. If the scan tool indicates DTC P0315 failed or did not run, refer to «DTC P0315»(ref-188841-S27719406962005090200000) . If any other DTCs set, refer to «Diagnostic Trouble Code (DTC) List»(ref-188782-S08542865492005090200000) for the applicable DTC that set.
7. Turn OFF the ignition for 30 seconds after the learn procedure is completed successfully.
8. The CKP system variation learn procedure is also required when the following service procedures have been performed, regardless of whether DTC P0315 is set: Engine replacement ECM replacement A harmonic balancer replacement Crankshaft replacement CKP sensor replacement Any engine repairs which disturb the crankshaft to CKP sensor relationship

Tools Required

J 39194-C O2 Sensor Wrench. See Special Tools and Equipment .

J 39194-C O2 Sensor Wrench. See Special Tools and Equipment .

J 34730-1A Fuel Pressure Gage. See Special Tools and Equipment .

1. Disconnect the negative battery cable. Refer to «Battery Negative Cable Disconnect/Connect Procedure»(ref-188769-S19455074222005090200000) in Engine Electrical.
2. Connect the J 34730-1A to the fuel pressure connection. See «Special Tools and Equipment»(ref-188785-S10968964482005090200000) . Refer to «Fuel Pressure Gage Installation and Removal»(ref-188785-S36989663072005090200000) .
3. Install the bleed hose into an approved container and open the valve to bleed the system pressure. The fuel connections are now safe for servicing.
4. Disconnect the fuel pressure gage from the fuel pressure connection. Refer to «Fuel Pressure Gage Installation and Removal»(ref-188785-S36989663072005090200000) .

J 34730-1A Fuel Pressure Gage. See Special Tools and Equipment .

SA9156E Fuel Tank Lock Ring Remover. See Special Tools and Equipment .

J 45722 Fuel Tank Lock Ring Remover. See Special Tools and Equipment .

SA9127E Gage Bar Set

Using The Fuel Pump

Scheme 42

Using the fuel pump to drain the tank is the easiest procedure if the pump is operable. The fuel can be pumped out with the vehicle on the ground or on the hoist.

On The Ground

1. Relieve the fuel system pressure. Refer to «Fuel Pressure Relief Procedure»(ref-188785-S01720955142005090200000) .
2. Disconnect the fuel feed line at the fuel rail and install the 3/8 in. x 1/4 in. quick connect from the SA9127E-7 into the fuel feed line.
3. Connect a suitable drain hose to the other end of the adapter and connect the drain hose into a certified fuel handling cart.
4. Connect the scan tool to the vehicle and turn the ignition ON.
5. Energize the fuel pump using the scan tool. Refer to «Fuel Injector Circuit Diagnosis»(ref-188819-S15241638882005090200000) .
6. Pump out the fuel until no more than 1/4 tank remains.

On The Hoist

1. Connect the scan tool to the vehicle diagnostic connector and turn the ignition ON.
2. Relieve the fuel system pressure. Refer to «Fuel Pressure Relief Procedure»(ref-188785-S01720955142005090200000) .
3. Raise the vehicle on a hoist to a comfortable working height, keeping the scan tool outside of the vehicle and accessible from under the car.
4. Disconnect the chassis fuel feed line at the filter outlet, the 3/8 in. line.
5. Install the 3/8 in. x 1/4 in. quick connect (1) adapter from the SA9127E-7 onto the fuel feed line.
6. Connect a suitable drain hose to the other end of the adapter, and connect the drain hose to a certified fuel handling cart.
7. Energize the fuel pump using the scan tool. Refer to «Fuel Injector Circuit Diagnosis»(ref-188819-S15241638882005090200000) .
8. Pump out the fuel until no more than 1/4 tank remains.

Siphoning The Fuel Tank

If the fuel pump is inoperative, the tank can be drained by siphoning from the tank. A suitable means is through the fuel filler pipe with the correct type and stiffness of tubing as used with the SA9804E .

1. Disconnect the negative battery cable.
2. Open the fuel filler door and remove the gas cap.
3. Insert the siphon hose guide/funnel into the fuel filler pipe.
4. Insert the SA9804E into the guide funnel and into the fuel filler pipe. Some resistance may be encountered when the tip of the siphon hose reaches the inlet check valve. Repeated probing may be necessary to slide the hose tip through the check valve cage.
5. Begin the fuel siphoning process. Place the fuel into an approved fuel container.
6. Remove the siphon hose from the fuel filler pipe after draining is complete.

SA9127E-7 Fuel Pressure/Flow Adapter

After it is determined that the fuel system is contaminated, the following procedure to clean it is recommended.

1. Place the vehicle on a hoist and open the hood.
2. Disconnect the negative battery cable.
3. Drain the fuel tank. Refer to «Fuel Tank Draining Procedure»(ref-188785-S10629870142005090200000) .
4. Remove the fuel tank. Refer to «Fuel Tank Replacement»(ref-188785-S14932727402005090200000) .
5. Disconnect the fuel feed line at the fuel rail.
6. With compressed air, blow out the fuel feed. Catch the fuel in a container at the opposite end of the line.
7. Remove the fuel pump modules. Refer to «Fuel Tank Module Replacement - Primary»(ref-188785-S13892417762005090200000) and «Fuel Tank Module Replacement - Secondary»(ref-188785-S31779781932005090200000) .
8. Inspect the inlet filter on the primary pump. If plugged or damaged, the fuel pump module must be replaced.
9. Flush the tank with hot water for at least 6 minutes. Invert and drain. All metal chips/debris must be removed from the tank prior to installation.
10. Install the fuel pump modules to the fuel tank using a new fuel pump seal. Do not connect the fuel feed line to the new filter.
11. Install the fuel tank to the vehicle.
12. Connect the fuel line to the fuel rail.
13. Put at least 22.7 liters (6 gallons) of clean fuel into the fuel tank.
14. Connect the negative battery cable. Tighten: Tighten the battery terminal bolt to 17 N.m (13 lb ft).
15. Connect a scan tool to the vehicle and turn the ignition ON.
16. Raise the vehicle on a hoist and install the male quick connect adapter SA9127E-7 into the fuel feed line.
17. Install the drain hose to the adapter and place the other end in an approved container.
18. Energize the fuel pump with the scan tool for 1-2 minutes. Refer to Energizing the Fuel Pump. This will pump about 1.9 liters (2 quarts) of fuel and purge any debris in the fuel pump.
19. Disconnect the fuel drain hose adapter at the fuel feed line and connect the fuel line to the fuel filter.
20. Energize the fuel pump and check all connections for leaks.
21. De-energize the pump, lower the vehicle, and start the engine.

Spark Plug Usage

1. Ensure that the correct spark plug is installed. An incorrect spark plug causes driveability conditions. Refer to «Ignition System Specifications»(ref-188786-S18194948442005090200000) for the correct spark plug.
2. Ensure that the spark plug has the correct heat range. An incorrect heat range causes the following conditions: Spark plug fouling - colder plug Pre-ignition causing spark plug and/or engine damage - hotter plug

Powertrain

The powertrain has electronic controls to reduce exhaust emissions while maintaining excellent driveability and fuel economy. The engine control module (ECM) is the control center of this system. The ECM monitors numerous engine and vehicle functions. The ECM constantly looks at the information from various sensors and other inputs, and controls the systems that affect vehicle performance and emissions. The ECM also performs the diagnostic tests on various parts of the system. The ECM can recognize operational problems and alert the driver with the malfunction indicator lamp (MIL). When the ECM detects a malfunction, the ECM stores a diagnostic trouble code (DTC). The problem area is identified by the particular DTC that is set. Review the components and wiring diagrams in order to determine which systems are controlled by the ECM.

The following are some of the functions that the ECM controls

1. The engine fueling
2. The ignition control (IC)
3. The knock sensor (KS) system
4. The evaporative emissions (EVAP) system
5. The generator
6. The A/C clutch control
7. The cooling fan control

Engine Control Module Function

The ECM constantly looks at the information from various sensors and other inputs and controls systems that affect vehicle performance and emissions. The ECM also performs diagnostic tests on various parts of the system. The ECM can recognize operational problems and alert the driver with the malfunction indicator lamp (MIL). When the ECM detects a malfunction, the ECM stores a diagnostic trouble code (DTC). The problem area is identified by the particular DTC that is set. The input and output devices in the ECM include analog-to-digital converters, signal buffers, counters, and output drivers. The output drivers are electronic switches that complete a ground or voltage circuit when turned on. Most ECM controlled components are operated by output drivers. The ECM monitors these driver circuits for proper operation and, in most cases, can set a DTC corresponding to the controlled device if a problem is detected.

Warm-up Cycle

The ECM uses warm-up cycles to run some diagnostics and to clear any diagnostic trouble codes (DTCs). A warm-up cycle occurs when the engine coolant temperature increases 22°C (40°F) from the start-up temperature. The engine coolant must also achieve a minimum temperature of 71°C (160°F). The ECM counts the number of warm-up cycles in order to clear the malfunction indicator lamp (MIL). The ECM will clear the DTCs when 40 consecutive warm-up cycles occur without a malfunction.

Fuel Filler Cap

Note. If a fuel tank filler cap requires replacement, use only a fuel tank filler cap with the same features. Failure to use the correct fuel tank filler cap can result in a serious malfunction of the fuel and EVAP system.

The fuel fill pipe has a tethered fuel filler cap. A torque-limiting device prevents the cap from being over-tightened. To install the cap, turn the cap clockwise until you hear audible clicks. This indicates that the cap is correctly torqued and fully seated. A fuel filler cap that is not fully seated may cause a malfunction in the emission system.

Scheme 43

The primary fuel tank module is located inside of the right side of the fuel tank. The primary fuel tank module consists of the following major components

1. The fuel level sensor (4)
2. The fuel pump and reservoir assembly
3. The fuel strainer
4. The primary jet pump
5. The secondary jet pump
6. The fill limiter vent valve (6)
7. The fuel pressure sensor (1)
8. The fuel filter (3)
9. The fuel pressure regulator (5)
10. The fuel transfer pipe (2)

Scheme 44

The secondary fuel tank module is located inside of the left side of the fuel tank. The secondary fuel tank module consists of the following major components

1. The fuel level sensor (1)
2. The fuel pick-up (2)

Fuel Level Sensor

The fuel level sensor consists of a float, a wire float arm, and a ceramic resistor card. The position of the float arm indicates the fuel level. The fuel level sensor contains a variable resistor which changes resistance in correspondence with the position of the float arm. The control module sends the fuel level information via the CAN serial data to the body control module (BCM). The instrument panel cluster (IPC) displays the fuel level as determined by the BCM. This information is used for the IPC fuel gage and the low fuel warning indicator, if applicable. The control module also monitors the fuel level input for various diagnostics.

Scheme 45

The fuel pump (2) is mounted in the primary fuel tank module reservoir. The fuel pump is an electric high-pressure pump. Fuel is pumped to the fuel injection system at a specified flow and pressure. The fuel pump delivers a constant flow of fuel to the engine even during low fuel conditions and aggressive vehicle maneuvers. The control module controls the electric fuel pump operation through a fuel pump relay.

Scheme 46

The primary jet pump (1) is located in the primary fuel tank module. Fuel pump flow loss, caused by vapor expulsion in the pump inlet chamber, is diverted to the primary jet pump and the secondary jet pump (2) through a restrictive orifice located on the pump cover. The primary jet pump fills the reservoir of the primary fuel tank module.

Scheme 47

The secondary jet pump (1) creates a venturi action which causes the fuel to be drawn from the secondary side of the fuel tank, through the transfer pipe, to the primary side of the fuel tank.

Fuel Strainer

The fuel strainer attaches to the lower end of the primary fuel tank module. The fuel strainer is made of woven plastic. The functions of the fuel strainer are to filter contaminants and to wick fuel. The fuel strainer normally requires no maintenance. Fuel stoppage at this point indicates that the fuel tank contains an abnormal amount of sediment or contamination.

Fuel Filter

The fuel filter (1) is located in the primary fuel tank module. The paper filter element traps particles in the fuel that may damage the fuel injection system. The filter housing is made to withstand maximum fuel system pressure, exposure to fuel additives, and changes in temperature.

Fuel Pressure Regulator

The fuel pressure regulator is integrated into the fuel filter cover on the primary fuel tank module. The fuel pressure regulator uses a spring with a preset tension and a stainless steel ball inserted into a precision ground seat in order to regulate fuel pressure. This type of fuel pressure regulator is not serviceable.

Fuel Feed Pipes

The fuel feed pipe carries fuel from the fuel tank to the fuel injection system. The fuel pipe consists of 3 sections

1. The rear fuel pipe is located from the top of the fuel tank to the chassis fuel pipe. The rear fuel pipe is constructed of nylon.
2. The chassis fuel pipe is located under the vehicle and connects the rear fuel pipe to the engine compartment fuel pipe. The chassis fuel pipe is constructed of steel with a section of rubber hose.
3. The engine compartment fuel pipe connects the chassis fuel feed pipe to the fuel rail. The engine compartment fuel pipe is constructed of steel.

Nylon Fuel Pipes

Nylon pipes are constructed to withstand maximum fuel system pressure, exposure to fuel additives, and changes in temperature. The following 2 sizes of nylon pipes are used

1. 9.53 mm (3/8 in) ID for the fuel feed
2. 12.7 mm (1/2 in) ID for the vent

Heat resistant rubber hose or corrugated plastic conduit protect the sections of the pipes that are exposed to chafing, high temperature, or vibration.

Nylon fuel pipes are somewhat flexible and can be formed around gradual turns under the vehicle. However, if nylon fuel pipes are forced into sharp bends, the pipes kink and restrict the fuel flow. Also, once exposed to fuel, nylon pipes may become stiffer and are more likely to kink if bent too far. Take special care when working on a vehicle with nylon fuel pipes.

Quick-Connect Fittings

Quick-connect fittings provide a simplified means of installing and connecting fuel system components. The fittings consist of a unique female connector and a compatible male pipe end. O-rings, located inside the female connector, provide the fuel seal. Integral locking tabs inside the female connector hold the fittings together.

Fuel Pipe O-rings

O-rings seal the threaded connections in the fuel system. The fuel system O-ring seals are made of special material. Service the O-ring seals with the correct service part.

Scheme 48

The fuel rail assembly attaches to the engine intake manifold. The fuel rail assembly performs the following functions

1. Positions the injectors (5) in the intake manifold
2. Distributes fuel evenly to the injectors
3. Integrates the fuel pulse dampener (2) into the fuel metering system

Scheme 49

The fuel injector assembly is a solenoid device controlled by the control module that meters pressurized fuel to a single engine cylinder. The control module energizes the high-impedance, 12 ohm, injector solenoid (4) to open a normally closed ball valve (1). This allows fuel to flow into the top of the injector, past the ball valve, and through a director plate (3) at the injector outlet. The director plate has machined holes that control the fuel flow, generating a spray of finely atomized fuel at the injector tip. Fuel from the injector tip is directed at the intake valve, causing the fuel to become further atomized and vaporized before entering the combustion chamber. This fine atomization improves fuel economy and emissions.

Scheme 50

The rapid opening and closing of the fuel injectors cause pressure fluctuation in the fuel rail. The result is that the amount of injected fuel will be more or less than the desired amount. Mounted on the fuel rail, the pulsation damper reduces these pressure fluctuations. When pressure suddenly begins to drop, the spring-loaded diaphragm extends slightly decreasing fuel rail volume. This will momentarily prevent fuel pressure from becoming too low.

Starting Mode

When the ignition is first turned ON, the control module energizes the fuel pump relay for 2 seconds. This allows the fuel pump to build pressure in the fuel system. The control module calculates the air/fuel ratio based on inputs from the engine coolant temperature (ECT), manifold absolute pressure (MAP), and throttle position (TP) sensors. The system stays in starting mode until the engine speed reaches a predetermined RPM.

Clear Flood Mode

If the engine floods, clear the engine by pressing the accelerator pedal down to the floor and then crank the engine. When the TP sensor is at wide open throttle (WOT), the control module reduces the fuel injector pulse width in order to increase the air to fuel ratio. The control module holds this injector rate as long as the throttle stays wide open and the engine speed is below a predetermined RPM. If the throttle is not held wide open, the control module returns to the starting mode.

Run Mode

The run mode has 2 conditions called Open Loop and Closed Loop. When the engine is first started and the engine speed is above a predetermined RPM, the system begins Open Loop operation. The control module ignores the signal from the heated oxygen sensor (HO2S). The control module calculates the air/fuel ratio based on inputs from the ECT, MAP, and TP sensors. The system stays in Open Loop until meeting the following conditions

1. The HO2S has varying voltage output, showing that the HO2S is hot enough to operate properly.
2. The ECT sensor is above a specified temperature.
3. A specific amount of time has elapsed after starting the engine.

Specific values for the above conditions exist for this engine, and are stored in the electrically erasable programmable read-only memory (EEPROM). The system begins Closed Loop operation after reaching these values. In Closed Loop, the control module calculates the air/fuel ratio, injector ON time, based upon the signal from various sensors, but mainly from the HO2S. This allows the air/fuel ratio to stay very close to 14.7:1.

Acceleration Mode

When the driver pushes on the accelerator pedal, air flow into the cylinders increases rapidly. To prevent possible hesitation, the control module increases the pulse width to the injectors to provide extra fuel during acceleration. This is also known as power enrichment. The control module determines the amount of fuel required based upon the TP, the ECT, the MAP, and the engine speed.

Deceleration Mode

When the driver releases the accelerator pedal, air flow into the engine is reduced. The control module monitors the corresponding changes in the TP and the MAP. The control module shuts OFF fuel completely if the deceleration is very rapid, or for long periods, such as long, closed-throttle coast-down. The fuel shuts OFF in order to prevent damage to the catalytic converters.

Battery Voltage Correction Mode

When the battery voltage is low, the control module compensates for the weak spark delivered by the ignition system in the following ways

1. Increasing the amount of fuel delivered
2. Increasing the idle RPM
3. Increasing the ignition dwell time

Fuel Cutoff Mode

The control module cuts OFF fuel from the fuel injectors when the following conditions are met in order to protect the powertrain from damage and improve driveability

1. The ignition is OFF. This prevents engine run-on.
2. The ignition is ON but there is no ignition reference signal. This prevents flooding or backfiring.
3. The engine speed is too high, above red line.
4. The vehicle speed is too high, above rated tire speed.
5. During an extended, high speed, closed throttle coast down-This reduces emissions and increases engine braking.
6. During extended deceleration, in order to prevent damage to the catalytic converters

Fuel Trim

The control module controls the air/fuel metering system in order to provide the best possible combination of driveability, fuel economy, and emission control. The control module monitors the HO2S signal voltage while in Closed Loop and regulates the fuel delivery by adjusting the pulse width of the injectors based on this signal. The ideal fuel trim (FT) values are around 0 percent for both short and long term FT. A positive FT value indicates the control module is adding fuel in order to compensate for a lean condition by increasing the pulse width. A negative FT value indicates that the control module is reducing the amount of fuel in order to compensate for a rich condition by decreasing the pulse width. A change made to the fuel delivery changes the long and short term FT values. The short term FT values change rapidly in response to the HO2S signal voltage. These changes fine tune the engine fueling. The long term FT makes coarse adjustments to fueling in order to re-center and restore control to short term FT. A scan tool can be used to monitor the short and long term FT values. The long term FT diagnostic is based on an average of several of the long term speed load learn cells. The control module selects the cells based on the engine speed and engine load. If the control module detects an excessively lean or rich condition, the control module will set a FT DTC.

EVAP System Components

The EVAP system consists of the following components

EVAP Canister

The canister is filled with carbon pellets used to absorb and store fuel vapors. Fuel vapor is stored in the canister until the control module determines that the vapor can be consumed in the normal combustion process.

EVAP Purge Valve

The EVAP purge valve controls the flow of vapors from the EVAP system to the intake manifold. This normally closed valve is pulse width modulated (PWM) by the control module to precisely control the flow of fuel vapor to the engine. The valve will also be opened during some portions of the EVAP testing, allowing engine vacuum to enter the EVAP system.

EVAP Vent Valve

The EVAP vent valve controls fresh airflow into the EVAP canister. The valve is normally open. The control module will command the valve closed during some EVAP tests, allowing the system to be tested for leaks.

Fuel Tank Pressure Sensor

The FTP sensor measures the difference between the pressure or vacuum in the fuel tank and outside air pressure. The control module provides a 5-volt reference and a ground to the FTP sensor. The FTP sensor provides a signal voltage back to the control module that can vary between 0.1-4.9 volts. As FTP increases, FTP sensor voltage decreases, high pressure = low voltage. As FTP decreases, FTP voltage increases, low pressure or vacuum = high voltage.

EVAP Service Port

The EVAP service port is located in the EVAP purge pipe between the EVAP purge valve and the EVAP canister. The service port is identified by a green colored cap.

Crankshaft Reluctor Wheel

The crankshaft reluctor wheel is part of the crankshaft. The reluctor wheel has seven machined notches, six of which are equally spaced 60 degrees apart. The seventh notch is spaced 10 degrees after one of the 60-degree notches. The 10-degree notch is used to synchronize the engine position, while the other notches are used to provide cylinder location during a revolution.

Crankshaft Position (CKP) Sensor

The crankshaft position (CKP) sensor is a permanent magnet generator, known as a variable reluctance sensor. The CKP sensor produces an AC voltage of different amplitude and frequency. The frequency depends on the velocity of the crankshaft. The AC voltage output depends on the crankshaft position and the battery voltage. The CKP sensor works in conjunction with a 7X reluctor wheel attached to the crankshaft. The CKP sensor produces seven pulses for each revolution of the crankshaft. The pulse from the 10-degree notch is known as the sync pulse. The sync pulse is used to synchronize the coil firing sequence with the crankshaft position. The CKP sensor is used for ignition timing, the fuel injector timing, misfire diagnostics and tachometer display. The CKP sensor is connected tot he ECM by a signal circuit and a low reference circuit.

Scheme 51

The powertrain control module (PCM) supplies a signal on each of the ignition control (IC) timing control circuits to the ignition control module (ICM). The ICM fires the correct ignition coil at the correct time based on the signals. The ICM detects if cylinder 1 or cylinder 3 is on the compression stroke by sensing the secondary voltage and polarity of each side of the ignition coil. The ICM detects this voltage with sensing circuitry integrated into each ignition coil. The higher voltage is on the compressing cylinder. This is called compression sense ignition. The ICM provides a synthesized cam signal to the PCM based on these inputs. The PCM uses the cam signal to synchronize fuel injection. This system consists of the following circuits

1. An ignition voltage circuit
2. A ground circuit
3. A camshaft position (CMP) sensor signal circuit
4. An IC timing control circuit for cylinders #1 and #4
5. An IC timing control B circuit for cylinders #2 and #3

Engine Control Module (ECM)

The ECM controls all ignition system functions, and constantly corrects the spark timing. The ECM monitors information from various sensor inputs that include the following

1. The throttle position (TP) sensor
2. The engine coolant temperature (ECT) sensor
3. The intake air temperature (IAT) sensor
4. The vehicle speed sensor (VSS)
5. The transmission gear position or range information sensors
6. The engine knock sensors (KS)

Purpose

The throttle actuator control (TAC) system delivers improved throttle response and greater reliability and eliminates the need for mechanical cable. The TAC system performs the following functions

1. Accelerator pedal position sensing
2. Throttle positioning to meet driver and engine demands
3. Throttle position sensing
4. Internal diagnostics
5. Cruise control functions
6. Manage TAC electrical power consumption

The TAC system includes the following components

1. The accelerator pedal position (APP) sensors
2. The throttle body assembly
3. The engine control module (ECM)

Accelerator Pedal Position (APP) Sensor

The accelerator pedal contains 2 individual APP sensors within the assembly. The APP sensors 1 and 2 are potentiometer type sensors each with 3 circuits

1. A 5-volt reference circuit
2. A low reference circuit
3. A signal circuit

The APP sensors are used to determine the pedal angle. The ECM provides each APP sensor a 5-volt reference circuit and a low reference circuit. The APP sensors provide the ECM with signal voltage proportional to the pedal movement. The APP sensor 1 signal voltage at rest position is near the low reference and increases as the pedal is actuated. The APP sensor 2 signal voltage at rest position is near the 5-volt reference and decreases as the pedal is actuated.

Engine Control Module

The ECM is the control center for the TAC system. The ECM determines the drivers intent and then calculates the appropriate throttle response. The ECM achieves throttle positioning by providing a pulse width modulated voltage to the TAC motor.

Normal Mode

During the operation of the TAC system, several modes or functions are considered normal. The following modes may be entered during normal operation

1. Minimum pedal value-At key-up the ECM updates the learned minimum pedal value.
2. Minimum TP values-At key-up the ECM updates the learned minimum TP value. In order to learn the minimum TP value, the throttle blade is moved to the closed position.
3. Ice break mode-If the throttle is not able to reach a predetermined minimum throttle position, the ice break mode is entered. During the ice break mode, the ECM commands the maximum pulse width several times to the throttle actuator motor in the closing direction.
4. Battery saver mode-After a predetermined time without engine RPM, the ECM commands the battery saver mode. During the battery saver mode, the TAC module removes the voltage from the motor control circuits, which removes the current draw used to maintain the idle position and allows the throttle to return to the spring loaded default position.

Reduced Engine Power Mode

When the ECM detects a condition with the TAC system, the ECM may enter a reduced engine power mode. Reduced engine power may cause one or more of the following conditions

1. Acceleration limiting-The ECM will continue to use the accelerator pedal for throttle control; however, the vehicle acceleration is limited.
2. Limited throttle mode-The ECM will continue to use the accelerator pedal for throttle control; however, the maximum throttle opening is limited.
3. Throttle default mode-The ECM will turn off the throttle actuator motor and the throttle will return to the spring loaded default position.
4. Forced idle mode-The ECM will perform the following actions: Limit engine speed to idle by positioning the throttle position, or by controlling the fuel and spark if the throttle is turned off. Ignore the accelerator pedal input.
5. Engine shutdown mode-The ECM will disable fuel and de-energize the throttle actuator.

The knock sensor (KS) system enables the control module to control the ignition timing for the best possible performance while protecting the engine from potentially damaging levels of detonation. The control module uses the KS system to test for abnormal engine noise that may indicate detonation, also known as spark knock.