Outputs
AIR CONDITIONING CLUTCH RELAY-PCM OUTPUTThe air conditioning clutch relay is located in the PDC. The inside top of the PDC cover has a label showing relay and fuse location.
The PCM controls the air conditioning clutch relay ground circuit. The A/C clutch relay coil side contains a 10 amp fuse between the buss bar in the Power Distribution Center (PDC) and the relay. The power side of this relay is fused with a 40 amp fuse. When the PCM receives an air conditioning input, it grounds the A/C compressor clutch relay and the radiator fan relay.
When the PCM senses low idle speeds or wide open throttle through the throttle position sensor, it removes the ground for the A/C compressor clutch relay. When the relay de-energizes, the contacts open preventing air conditioning clutch engagement. Also, if the PCM senses a part throttle launch condition, it disables the A/C compressor clutch for several seconds.
AUTOMATIC SHUTDOWN RELAY-PCM OUTPUT
Power Distribution Center (PDC):
The ASD relay and fuel pump relay are located in the Power Distribution Center (PDC) near the Air Cleaner. The inside top of the PDC cover has a label showing relay and fuse location.
The PCM operates the Automatic Shut Down (ASD) relay and fuel pump relays. The PCM operates them by switching the ground path for the solenoid side of the relays on and off.
The ASD relay connects battery voltage to the fuel injectors and ignition coil. The fuel pump relay connects battery voltage to the fuel pump.
A buss bar in the Power Distribution Center (PDC) supplies voltage to the coil side and contact side of the relay. The ASD relay power circuit contains a 20 amp fuse between the buss bar in the PDC and the relay. The fuses are located in the PDC. Refer to the Wiring Diagrams for circuit information.
The PCM controls the relay by switching the ground path for the solenoid side of the relay on and off. The PCM turns the ground path off when the ignition switch is in the Off position unless the O2 Heater Monitor test is being run. When the ignition switch is in the Run or Start position, the PCM monitors the crankshaft position sensor and camshaft position sensor signals to determine engine speed and ignition timing (coil dwell). If the PCM does not receive the crankshaft position sensor and camshaft position sensor signals when the ignition switch is in the Run position, it will de-energize the ASD relay.
PROPORTIONAL PURGE SOLENOID-PCM OUTPUT
Proportional Purge Solenoid:
The solenoid attaches to a bracket near the front engine mount. To operate correctly, the solenoid must be installed with the electrical connector on top.
The EVAP purge solenoid regulates the rate of vapor flow from the EVAP canister to the throttle body. The PCM operates the solenoid.
During the cold start warm-up period and the hot start time delay, the PCM does not energize the solenoid. When de-energized, no vapors are purged.
The proportional purge solenoid operates at a frequency of 200 hz and is controlled by an engine controller circuit that senses the current being applied to the proportional purge solenoid and then adjusts that current to achieve the desired purge flow. The proportional purge solenoid controls the purge rate of fuel vapors from the vapor canister and fuel tank to the engine intake manifold.
ELECTRIC EGR TRANSDUCER-PCM OUTPUT-2.4/2.5L ENGINES
Electric EGR Transducer-2.4L Engine:
EGR Control Valve-2.5L Engine:
The solenoid/transducer and EGR valve mount to the rear of the cylinder head.
Electronic EGR Transducer:
The Electric EGR Transducer contains an electrically operated solenoid and a back-pressure controlled vacuum transducer. The PCM operates the solenoid based on inputs from the multiport fuel injection system. The solenoid/transducer and EGR valve are serviced as an assembly
When the PCM energizes the solenoid, vacuum does not reach the transducer. Vacuum flows to the transducer when the PCM de-energizes the solenoid.
When exhaust system back-pressure becomes high enough, it fully closes a bleed valve in the vacuum transducer. When the PCM de-energizes the solenoid and back-pressure closes the transducer bleed valve, vacuum flows through the transducer to operate the EGR valve.
De-energizing the solenoid, but not fully closing the transducer bleed hole (because of low back-pressure), varies the strength of the vacuum signal applied to the EGR valve. Varying the strength of the vacuum signal changes the amount of EGR supplied to the engine. This provides the correct amount of exhaust gas recirculation for different operating conditions.
GENERATOR FIELD-PCM OUTPUT
The PCM regulates the charging system voltage within a range of 12.9 to 15.0 volts. Refer to the Battery for information and refer to the Charging for information.
IDLE AIR CONTROL MOTOR-PCM OUTPUT
Idle Air Control Motor Air Bypass Passage-2.4L:
Idle Air Control Motor Air Bypass Passage-2.5L:
The Idle Air Control (IAC) motor is mounted on the throttle body. The PCM operates the idle air control motor.
The PCM adjusts engine idle speed through the idle air control motor to compensate for engine load, coolant temperature or barometric pressure changes.
The throttle body has an air bypass passage that provides air for the engine during closed throttle idle. The idle air control motor pintle protrudes into the air bypass passage and regulates air flow through it.
The PCM adjusts engine idle speed by moving the IAC motor pintle in and out of the bypass passage. The adjustments are based on inputs the PCM receives. The inputs are from the throttle position sensor, crankshaft position sensor, coolant temperature sensor, MAP sensor, vehicle speed sensor and various switch operations (brake, park/neutral, air conditioning).
DATA LINK CONNECTOR
Data Link (Diagnositc) Connector:
The data link connector is located inside the vehicle, under the instrument panel, at the driver's kick panel.
The data link connector (diagnostic connector) links the DRB scan tool with the Powertrain Control Module (PCM). Refer to On-Board Diagnostics in the Emission Control.
FUEL INJECTORS-PCM OUTPUT
Fuel Injector:
All engines use electrically operated top feed fuel injectors.
The Automatic Shutdown (ASD) relay supplies battery voltage to the fuel injectors. The PCM controls the ground path for each injector in sequence. By switching the ground paths on and off, the PCM fine tunes injector pulse width. Injector pulse width refers to the amount of time an injector operates.
The PCM determines injector synchronization from the camshaft position sensor and crankshaft position sensor inputs. The PCM grounds the ASD and fuel pump relays when the ignition switch is initially rotated to the run position . The PCM will de-energize the ASD and fuel relays if it does not receive the camshaft position sensor and crankshaft position sensor inputs.
The PCM energizes the injectors in a sequential order during all engine operating conditions except start-up. For the first injector pulse width during start-up, all injectors are energized at the same time. Once the PCM determines crankshaft position, it begins energizing the injectors in sequence.
IGNITION COIL-PCM OUTPUT
Ignition Coil - 2.4L:
Ignition Coil - 2.5L:
The coil assembly consists of independent coils molded together. The coil assembly is mounted on the intake manifold.
High tension leads route to each cylinder from the coil. The coil fires two spark plugs every power stroke. One plug is the cylinder under compression, the other cylinder fires on the exhaust stroke. The PCM determines which of the coils to charge and fire at the correct time.
The Automatic Shutdown (ASD) relay provides battery voltage to the ignition coil. The PCM provides a ground contact (circuit) for energizing the coil. When the PCM breaks the contact, the energy in the coil primary transfers to the secondary causing the spark. The PCM will de-energize the ASD relay if it does not receive the crankshaft position sensor and camshaft position sensor inputs. Refer to Automatic Shutdown (ASD) Relay-PCM Output for relay operation.
MALFUNCTION INDICATOR (CHECK ENGINE) LAMP-PCM OUTPUT
The PCM supplies the malfunction indicator (check engine) lamp on/off signal to the instrument panel through the CCD Bus. The CCD Bus is a communications port. Various modules use the CCD Bus to exchange information.
The Check Engine lamp comes on each time the ignition key is turned ON and stays on for 3 seconds as a bulb test.
The Malfunction Indicator Lamp (MIL) stays on continuously, when the PCM has entered a Limp-In mode or identified a failed emission component. During Limp-in Mode, the PCM attempts to keep the system operational. The MIL signals the need for immediate service. In limp-in mode, the PCM compensates for the failure of certain components that send incorrect signals. The PCM substitutes for the incorrect signals with inputs from other sensors.
If the PCM detects active engine misfire severe enough to cause catalyst damage, it flashes the MIL. At the same time the PCM also sets a Diagnostic Trouble Code (DTC).
For signals that can trigger the MIL (Check Engine Lamp) refer to the On-Board Diagnostics Chart.
RADIATOR FAN RELAYS-PCM OUTPUT
The radiator fan relays are located in the PDC. The inside top of the PDC cover has a label showing relay and fuse location.
The PCM energizes the radiator fans through either the low or high speed radiator fan relay. The PCM controls the ground circuit for the coil side of the relay. Power for both relay coils is supplied through a 10 amp fuse in the PDC. Power for both relay contacts is supplied power through a 40 amp fuse in the PDC. Refer to the Wiring Diagrams for circuit information.
The PCM monitors the A/C compressor discharge (high side) pressure through the air conditioning pressure transducer. Depending on engine coolant temperature and A/C system high side pressure, both fans operate at either low or high speed.
SPEED CONTROL SERVOS-PCM OUTPUT
The PCM controls operation of the vacuum and the operator presses the on switch, the PCM provides power through the brake switch to the servo. When the speed control system is engaged following a set or resume, the PCM supplies a ground to the vacuum and or vent solenoids inside the servo as needed to maintain the selected vehicle speed. Refer to the Speed Control for more information.
TACHOMETER-PCM OUTPUT
The tachometer receives its information across the CCD Bus from the Body Control Module (BCM). Information on engine RPM is transmitted from the Powertrain Control Module (PCM) across the CCD Bus to the BCM. The BCM calculates the position of the tachometer pointer based on the input from the PCM and adjusts the position of the gauge pointer to the necessary position. This signal is sent over the CCD Bus to the instrument cluster.
5 VOLT SUPPLY-PCM OUTPUT
The PCM supplies 5 volts to the following sensors:
- A/C pressure transducer
- Engine coolant temperature sensor
- Manifold absolute pressure sensor Throttle position sensor
- Linear EGR solenoid
8-VOLT SUPPLY-PCM OUTPUT
The PCM supplies 8 volts to the crankshaft position sensor, camshaft position sensor.
THROTTLE BODY
Throttle Body - 2.4L Engines:
Throttle Body - 2.5L Engine:
The throttle body mounts to the intake manifold. The throttle position sensor and idle air control motor attach to the throttle body.
At above idle conditions, air flow through the throttle body is controlled by a cable operated throttle blade. During closed throttle idle conditions, the idle air control motor controls air flow. Refer to Idle Idle Air Control Motor.