Outputs

Fig 20 Power Distribution Center (PDC):

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.

The A/C compressor clutch relay is located in the Power Distribution Center (PDC) (Fig. 20). 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 one ground path. The PCM operates them by switching the ground path for the solenoid side of the relays on and off. Both relays turn on and off at the same time.

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 path 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 de-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) near the battery. A decal on the inside of the PDC covers shows the locations of each relay and fuse contained in the PDC.

Fig 21 Proportional Purge Solenoid:

PROPORTIONAL PURGE SOLENOID-PCM OUTPUT
All vehicles use a proportional purge solenoid. The 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 (Fig. 21) 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.

EXHAUST GAS RECIRCULATION (LSEGR)
The EGR valve consists of three major components. First there is the pintle, valve seat, and housing which contains and regulates the gas flow. Second there is the armature, return spring, and solenoid coil to provide the operating force to regulate the flow by changing the pintle position. The solenoid coil assembly is in parallel with a diode and connects to the two connectors in the connector assembly. The third major component which senses pintle position and is connected to the three connectors in the electrical connector.

The exhaust gas recirculation flow is determined by the engine controller. For a given set of conditions, the engine controller knows the ideal exhaust gas recirculation flow to optimize NOx and fuel economy as a function of the pintle position. Pintle position is obtained from the position sensor and the engine controller by adjusting the duty cycle of 128 Hz power supplied to the solenoid coil to obtain the correct position.

Fig 22 Manifold Tuning Valve:

MANIFOLD TUNING VALVE (MTV)-PCM OUTPUT
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 cross-over passage in that connects both sides of the intake manifold plenum (Fig. 22).

Fig 23 Short Runner Valve (SRV):

SHORT RUNNER VALVE (SRV)
The SRV system operates under WOT conditions above 5,000 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.

Fig 24 Idle Air Control Motor:

IDLE AIR CONTROL MOTOR-PCM OUTPUT
The idle air control motor attaches to the throttle body (Fig. 24). 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 or ambient conditions.

The throttle body has an air bypass passage that provides air for the engine at idle (the throttle blade is closed). 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 idle air control motor pintle in and out of the bypass passage. The adjustments are based on inputs the PCM receives. 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 air flow when the throttle closes quickly.

Fig 25 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 (Fig. 25).

Fig 26 Fuel Injector:

FUEL INJECTORS-PCM OUTPUT
The engines uses top feed injectors (Fig. 26).

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 150 C (600 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.

Fig 28 Ignition Coil:

IGNITION COIL-PCM OUTPUT
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 deenergize 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 in this section 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 PCI Bus. The PCI Bus is a communications port. Various modules use the PCI 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).

RADIATOR FAN RELAYS-PCM OUTPUT
The cooling system uses two fans. Both fans operate at two different speeds, low and high. Depending on engine coolant temperature and A/C system high side pressure, the both fans 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 fans.

The low speed and high speed fan relays are 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.

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 across the PCI Bus from the Body Control Module (BCM). Information on engine RPM is transmitted from the Powertrain Control Module (PCM) across the PCI 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 PCI Bus to the instrument cluster.

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.