Engine Controls Schematic Icons
Engine Controls Schematic Icons Icon Icon Definition NOTE: The OBD II symbol is used on the circuit diagrams in order to alert the technician that the circuit is essential for proper OBD II emission control circuit operation. Any circuit which fails and causes the malfunction indicator lamp (MIL) to turn ON, or causes emissions-related component damage, is identified as an OBD II circuit. IMPORTANT: Twisted-pair wires provide an effective shield that helps protect sensitive electronic components from electrical interference. If the wires were covered with shielding, install new shielding. In order to prevent electrical interference from degrading the performance of the connected components, you must maintain the proper specification when making any repairs to the twisted-pair wires shown: The wires must be twisted a minimum of 9 turns per 31 cm (12 in) as measured anywhere along the length of the wires The outside diameter of the twisted wires must not exceed 6.0 mm (0.25 in)
Scheme 387
Scheme 387: Engine Controls Schematic Icons
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Scheme 389
Scheme 389: Engine Controls Schematics
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Scheme 399
Scheme 400
Scheme 400: Engine Controls Component Views
| Callout | Component Name |
|---|
| 1 | Powertrain Control Module (PCM) |
| 2 | Radiator Support |
| 3 | Left Frame Rail |
| 4 | PCM Wire Harness Connectors |
Scheme 401
| Callout | Component Name |
|---|
| 1 | Fuse Block-Underhood |
| 2 | Forward Lamp Harness - C4 (GRN) |
| 3 | Chassis Harness - C3 (RED) |
| 4 | Fuse Block-Underhood Mounting Bracket |
| 5 | Left Front Wheel House |
| 6 | Left Front Inner Fender |
| 7 | Instrument Panel Harness - C1 (LT GRY) |
| 8 | Engine Harness - C2 (BLK) |
Scheme 402
| Callout | Component Name |
|---|
| 1 | Air Cleaner Assembly |
| 2 | Mass Air Flow (MAF)/Intake Air Temperature (IAT) Sensor Assembly |
| 3 | Air Inlet Tube |
| 4 | Generator |
Scheme 403
| Callout | Component Name |
|---|
| 1 | Crankshaft |
| 2 | Front Engine Cover |
| 3 | Crankshaft Position (CKP) Sensor |
Scheme 404
| Callout | Component Name |
|---|
| 1 | Crankshaft Position (CKP) Reluctor Wheel |
| 2 | Crankshaft |
| 3 | Engine Block |
Scheme 405
| Callout | Component Name |
|---|
| 1 | Throttle Position (TP) Sensor |
| 2 | Idle Air Control (IAC) Valve |
| 3 | Ignition Coil |
| 4 | Evaporative (EVAP) Canister Purge Solenoid |
| 5 | Engine Oil Pressure (EOP) Switch |
| 6 | Knock Sensor (KS) |
| 7 | Fuel Pressure Connection Valve |
| 8 | Positive Crankcase Ventilation Valve (PCV) |
Scheme 406
| Callout | Component Name |
|---|
| 1 | Throttle Body |
| 2 | Exhaust Gas Recirculation (EGR) Valve |
| 3 | Generator |
| 4 | Evaporative Emission (EVAP) Canister Purge Valve |
| 5 | Manifold Absolute Pressure (MAP) Sensor |
Scheme 407
| Callout | Component Name |
|---|
| 1 | Bank 1 Cylinder Head |
| 2 | Engine Coolant Temperature (ECT) Sensor |
Scheme 408
| Callout | Component Name |
|---|
| 1 | Engine Harness |
| 2 | Injector Assembly Electrical Connector |
| 3 | Throttle Body |
| 4 | Manifold Absolute Pressure (MAP) Sensor |
| 5 | Ignition Control Module (ICM) |
| 6 | Ignition Coil |
| 7 | Evaporative Emission (EVAP) Canister Purge Solenoid |
Scheme 409
| Callout | Component Name |
|---|
| 1 | Camshaft Position (CMP) Sensor |
| 2 | Engine Oil Pressure (EOP) Switch |
| 3 | Knock Sensor (KS) |
Scheme 410
| Callout | Component Name |
|---|
| 1 | HO2S Bank 2 Sensor 2 |
| 2 | HO2S Bank 1 Sensor 2 |
| 3 | HO2S Bank 1 Sensor 1 |
| 4 | HO2S Bank 2 Sensor 1 |
Scheme 411
| Callout | Component Name |
|---|
| 1 | Vehicle Speed Sensor (VSS) |
Scheme 412
| Callout | Component Name |
|---|
| 1 | Vehicle Speed Sensor (VSS) |
Scheme 413
| Callout | Component Name |
|---|
| 1 | Vehicle Speed Sensor (VSS) |
Scheme 414
| Callout | Component Name |
|---|
| 1 | Manual Transmission |
| 2 | Vehicle Speed Sensor (VSS) |
| 3 | Transfer Case (4WD) |
Scheme 415
| Callout | Component Name |
|---|
| 1 | Left Frame Rail |
| 2 | Evaporative Emission (EVAP) Canister Vent Solenoid |
| 3 | Fuel Tank |
| 4 | Evaporative Emission (EVAP) Canister |
Scheme 416
| Callout | Component Name |
|---|
| 1 | Secondary Air Injection (AIR) Pump |
| 2 | Vacuum Hose to AIR Solenoid |
| 3 | Low Pressure Switch |
| 4 | A/C Accumulator |
| 5 | AIR Hose to AIR Pipes |
| 6 | AIR Solenoid |
| 7 | AIR Pump Shut Off Valve |
| 8 | Fender to Cowl Brace |
Scheme 417
| Callout | Component Name |
|---|
| 1 | Fuel Tank |
| 2 | Fuel Tank Pressure (FTP) Sensor Connector |
| 3 | Fuel Level Sensor |
| 4 | Fuel Pump and Sender Assembly |
Malfunction Indicator Lamp (MIL) Operation
The malfunction indicator lamp (MIL) is located in the instrument panel cluster. The MIL will display as either SERVICE ENGINE SOON or one of the following symbols when commanded ON
Scheme 418
Scheme 418: Malfunction Indicator Lamp (MIL) Operation
Scheme 419
The MIL indicates that an emissions related fault has occurred and vehicle service is required.
The following is a list of the modes of operation for the MIL
- The MIL illuminates when the ignition is turned ON, with the engine OFF. This is a bulb test to ensure the MIL is able to illuminate.
- The MIL turns OFF after the engine is started if a diagnostic fault is not present.
- The MIL remains illuminated after the engine is started if the control module detects a fault. A diagnostic trouble code (DTC) is stored any time the control module illuminates the MIL due to an emissions related fault. The MIL turns OFF after three consecutive ignition cycles in which a Test Passed has been reported for the diagnostic test that originally caused the MIL to illuminate.
- The MIL flashes if the control module detects a misfire condition which could damage the catalytic converter.
- When the MIL is illuminated and the engine stalls, the MIL will remain illuminated as long as the ignition is ON.
- When the MIL is not illuminated and the engine stalls, the MIL will not illuminate until the ignition is cycled OFF and then ON.
Fuel System Overview
The fuel tank stores the fuel supply. The electric fuel pump supplies fuel through an in-line fuel filter to the fuel injection system. The fuel pump provides fuel at a higher rate of flow than is needed by the fuel injection system. The fuel pressure regulator maintains the correct fuel pressure to the fuel injection system. A separate pipe returns unused fuel to the fuel tank.
Fuel Metering Modes of Operation
The control module monitors voltages from several sensors in order to determine how much fuel to give the engine. The control module controls the amount of fuel delivered to the engine by changing the fuel injector pulse width. The fuel is delivered under one of several modes.
EVAP System Operation
The evaporative emission (EVAP) control system limits fuel vapors from escaping into the atmosphere. Fuel tank vapors are allowed to move from the fuel tank, due to pressure in the tank, through the vapor pipe, into the EVAP canister. Carbon in the canister absorbs and stores the fuel vapors. Excess pressure is vented through the vent line and EVAP vent solenoid valve to the atmosphere. The EVAP canister stores the fuel vapors until the engine is able to use them. At an appropriate time, the control module will command the EVAP purge solenoid valve ON, allowing engine vacuum to be applied to the EVAP canister. With the EVAP vent solenoid valve OFF, fresh air is drawn through the vent solenoid valve and the vent line to the EVAP canister. Fresh air is drawn through the canister, pulling fuel vapors from the carbon. The air/fuel vapor mixture continues through the EVAP purge pipe and EVAP purge solenoid valve into the intake manifold to be consumed during normal combustion. The control module uses several tests to determine if the EVAP system is leaking.
Distributor Ignition (DI) System Description
The distributor ignition (DI) system is responsible for producing and controlling a high energy secondary spark. This spark is used to ignite the compressed air/fuel mixture at precisely the correct time. This provides optimal performance, fuel economy, and control of exhaust emissions. This ignition system consists of a single ignition coil and ignition control module (ICM). Spark energy is delivered via a distributor cap, rotor, and secondary spark plug wires. The driver module within the ICM is commanded to operate the coil by the powertrain control module (PCM), that has complete control over spark timing. The DI system consists of the following components
Modes of Operation
There is one normal mode of operation, with the spark under PCM control. If the CKP pulses are lost the engine will not run. The loss of a CMP signal may result in a longer crank time since the PCM cannot determine which stroke the pistons are on. Diagnostic trouble codes are available to accurately diagnose the ignition system with a scan tool.
Sensor Description
This KS system uses one or two flat response two-wire sensors. The sensor uses piezo-electric crystal technology that produces an AC voltage signal of varying amplitude and frequency based on the engine vibration or noise level. The amplitude and frequency are dependant upon the level of knock that the KS detects. The control module receives the KS signal through a signal circuit. The KS ground is supplied by the control module through a low reference circuit.
The control module learns a minimum noise level, or background noise, at idle from the KS and uses calibrated values for the rest of the RPM range. The control module uses the minimum noise level to calculate a noise channel. A normal KS signal will ride within the noise channel. As engine speed and load change, the noise channel upper and lower parameters will change to accommodate the normal KS signal, keeping the signal within the channel. In order to determine which cylinders are knocking, the control module only uses KS signal information when each cylinder is near top dead center (TDC) of the firing stroke. If knock is present, the signal will range outside of the noise channel.
If the control module has determined that knock is present, it will retard the ignition timing to attempt to eliminate the knock. The control module will always try to work back to a zero compensation level, or no spark retard. An abnormal KS signal will stay outside of the noise channel or will not be present. KS diagnostics are calibrated to detect faults with the KS circuitry inside the control module, the KS wiring, or the KS voltage output. Some diagnostics are also calibrated to detect constant noise from an outside influence such as a loose/damaged component or excessive engine mechanical noise.
Air Intake System Description
The primary function of the air intake system is to provide filtered air to the engine. The system uses a cleaner element mounted in a housing. The cleaner housing is remotely mounted and uses intake ducts to route the incoming air into the throttle body. The secondary function of the air intake system is to muffle air induction noise. This is achieved through the use of resonators attached to the air intake ducts. the resonators are tuned to the specific powertrain. The mass air flow (MAF) sensor is attached to the outlet of the air cleaner housing. The air cleaner life indicator is located on an intake duct between the air cleaner housing and the throttle plate.
