Outputs

AIR CONDITIONING COMPRESSOR CLUTCH RELAY-PCM OUTPUT
The Powertrain Control Module (PCM) operates the air conditioning clutch relay ground circuit. The battery supplies power to the solenoid side of the relay The PCM grounds the relay when the operator puts the A/C or defrost switch in the ON position and it receives an acceptable input from the A/C pressure transducer. If the A/C pressure transducer input indicates high side pressure is too high or too low, the PCM will not ground the A/C compressor clutch relay

With the engine operating, the PCM cycles the air conditioning clutch on and off during A/C operation. When the PCM senses low idle speeds or wide open throttle through the throttle position sensor, it de-energizes the A/C compressor clutch relay

Power Distribution Center (PDC):

The A/C compressor clutch relay is located in the Power Distribution Center (PDC) near the battery. A decal on the inside of the PDC covers shows the locations of each relay and fuse contained in the PDC.

AUTOMATIC SHUT DOWN (ASD) AND FUEL PUMP RELAYS-PCM OUTPUT
The PCM operates the Automatic Shut Down (ASD) relay and fuel pump relay through two grounds. The PCM operates them by switching the ground path for the solenoid (coil) 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.

The PCM turns the ground paths off when the ignition switch is in the Off position. Both relays are off. When the ignition switch is in the On or Crank 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 a crankshaft position sensor signal and camshaft position sensor signal when the ignition switch is in the Run position, it de-energizes both relays. When the relays are dc-energized, battery voltage is not supplied to the fuel injectors, ignition coil and fuel pump.

The ASD relay and fuel pump relay are located in the Power Distribution Center (PDC). A decal on the inside of the PDC covers shows the locations of each relay and fuse contained in the PDC.

DUTY CYCLE EVAP PURGE SOLENOID-PCM OUTPUT
The duty cycle EVAP purge solenoid regulates the rate of vapor flow from the EVAP canister to the throttle body. The Powertrain Control Module (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 engine enters closed loop operation after it reaches a specified temperature and the programmed time delay ends. During closed loop operation, the PCM energizes and dc-energizes the solenoid 5 to 10 times per second, depending upon operating conditions. The PCM varies the vapor flow rate by changing solenoid pulse width. Pulse width is the amount of time the solenoid is energized.

Duty Cycle EVAP Purge Solenoid:

The EVAP purge solenoid and bracket attach to the right inner fender well next to the dash panel. The top of the solenoid has the word TOP on it.

The solenoid will not operate unless it is installed correctly. The EVAP purge solenoid shares a bracket with the MTV solenoid.

EGR Solenoid:

ELECTRONIC EGR TRANSDUCER SOLENOID-PCM OUTPUT
The electronic EGR transducer contains an electrically operated solenoid and a back-pressure transducer. The Powertrain Control Module (PCM) operates the solenoid. The PCM determines when to energize the solenoid. Exhaust system backpressure controls the transducer.

When the PCM energizes the solenoid, vacuum does not reach the transducer. Vacuum flows to the transducer when the PCM dc-energizes the solenoid.

When exhaust system back-pressure becomes high enough, it fully closes a bleed valve in the 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 vacuum applied to the EGR valve. Varying the strength of the vacuum changes the amount of EGR supplied to the engine. This provides the correct amount of exhaust gas recirculation for different operating conditions.

EVAP Purge And MTV Solenoids:

MANIFOLD TUNING VALVE (MTV) SOLENOID-PCM OUTPUT
The MTV solenoid regulates the supply of vacuum to the manifold tuning valve. The PCM controls the MTV solenoid. The manifold tuning valve optimizes acoustical tuning of the intake system during wide open throttle operation throughout the RPM range. The valve opens a crossover passage in that connects both sides of the intake manifold plenum.

When energized, the MTV solenoid allows vacuum to reach and close the manifold tuning valve. When not energized, the solenoid closes and vacuum bleeds off from the manifold tuning valve vacuum motor. The manifold tuning valve opens the crossover when the solenoid de-energizes.

The MTV solenoid shares a bracket with the duty cycle EVAP purge solenoid. The solenoids and bracket attach to the right inner fender well next to the dash panel (Fig. 24).

Short Runner Valve (SRV):

SHORT RUNNER VALVE (SRV)
The SRV system operates under WOT conditions above 5000 rpm to maximize engine performance. When actuated by the PCM, the SRV solenoid energizes, allowing mechanical linkage to redirect the intake air flow to six short runners. The PCM looks for a current spike when actuating the solenoid. If the spike is not present, the PCM sets the DTC.

GENERATOR FIELD-PCM OUTPUT
The PCM regulates the charging system voltage within a range of 12.9 to 15.0 volts.

Idle Air Control Motor:

Idle Air Passage:

IDLE AIR CONTROL MOTOR-PCM OUTPUT
The idle air control motor and housing attaches to the rear of the intake manifold plenum. The housing opens to the rear runner in the intake manifold plenum. A hose from the air cleaner plenum supplies filtered air to idle air control motor housing. The idle air control motor pintle protrudes into the housing and regulates air flow through it.

The PCM adjusts engine idle speed by moving the idle air control motor pintle in and out of the opening in the housing. The adjustments are based on inputs to the PCM. The inputs effecting idle speed include the throttle position sensor, road speed (from transmission control module), coolant temperature sensor, battery voltage and battery temperature. Also, various switch operations (brake, park/neutral, air conditioning) effect idle speed. The PCM prevents deceleration die out by increasing airflow when the throttle closes quickly.

Data Link Connector:

DATA LINK CONNECTOR-PCM OUTPUT
The data link connector (diagnostic connector) links the DRB scan tool with the Powertrain Control Module (PCM). The data link connector is located inside the vehicle, below instrument panel next to the center column.

Fuel Injector:

FUEL INJECTORS-PCM OUTPUT
This engine uses bottom feed injectors. Fuel from the rail enters the side of the injectors.

The Automatic Shut Down (ASD) relay supplies battery voltage to the 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 after receiving 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. During start-up, when the coolant temperature is below 15 °C (60 °F), all injectors are energized at the same time. Above 15 °C, the PCM energizes the injectors in sequence. Once the PCM determines crankshaft position, it begins energizing the injectors in sequence.

Ignition Coil Pack:

IGNITION COIL-PCM OUTPUT
The coil assembly consists of 3 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 Shut Down (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 sensor and camshaft sensor inputs. Refer to Automatic Shut Down (ASD) Relay and Fuel Pump Relay-PCM for relay operation.

The PCM determines which of the coils to charge and fire at the correct time. The Automatic Shut Down (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 sensor and camshaft sensor inputs. Refer to Automatic Shut Down (ASD) Relay and Fuel Pump Relay-PCM 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 Service Engine Soon 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).

The MIL can also display diagnostic trouble codes. Cycle the ignition switch on, off, on, off, on, within 5 seconds and any diagnostic trouble codes stored in the PCM will be displayed. Refer to Trouble Code Descriptions.

RADIATOR FAN RELAYS-PCM OUTPUT
The cooling system uses one fan. The fan operates at two different speeds, low and high. Depending on engine coolant temperature, A/C system high side pressure, and transmission temperature, the fan operate at either low or high. The PCM controls radiator fan speed by grounding the coil side of either the low speed fan relay or the high speed fan relay. The ignition switch supplies voltage to the coil sides of the relay. When the PCM grounds the coil side of the relay, the contacts close and the battery supplies power to the fan.

The low speed and high speed fan relays are located in the Power Distribution Center (PDC). A decal on the inside of the PDC cover shows the locations of each relay and fuse contained in the PDC.

SPEED CONTROL SERVOS-PCM OUTPUT
The PCM controls operation of the vacuum and vent solenoids inside the speed control servo. When 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.

TACHOMETER-PCM OUTPUT
The tachometer receives its information from the Powertrain Control Module (PCM). The PCM calculates the position of the tachometer pointer based on inputs and adjusts the position of the gauge pointer to the necessary position.

TORQUE MANAGEMENT
The PCM receives the torque management input from the transmission control module. The PCM receives the input when the transmission shifts gears. In response, the PCM shuts off a number of fuel injectors when the transmission shifts gears.

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.