Outputs

SPEED CONTROL SERVOS-PCM OUTPUT
OPERATION

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. Refer to the Speed Control for more information.

The vehicle speed sensor generates 8 pulses per sensor revolution. These signals, in conjunction with a closed throttle signal from the throttle position sensor, indicate a closed throttle deceleration to the PCM. Under deceleration conditions, the PCM adjusts the Idle Air Control (IAC) motor to maintain a desired MAP value.

When the vehicle is stopped at idle, a closed throttle signal is received by the PCM (but a speed sensor signal is not received). Under idle conditions, the PCM adjusts the IAC motor to maintain a desired engine speed.

The vehicle speed sensor signal is also used to operate the following functions or systems:
- Speedometer
- Speed control
- Daytime Running Lights (Canadian Vehicles only).

AIR CONDITIONING CLUTCH RELAY-PCM OUTPUT
DESCRIPTION
The air conditioning clutch relay is located in the PDC. The inside top of the PDC cover has a label showing relay and fuse location.

OPERATION
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
DESCRIPTION
The ASD relay is located in the PDC. The inside top of the PDC cover has a label showing relay and fuse location.

OPERATION
The automatic shutdown (ASD) relay supplies battery voltage to the fuel injectors, electronic ignition coil and the heating elements in the oxygen sensors.

A buss bar in the power distribution center (PDC) supplies voltage to the solenoid 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 fuse also protects the power circuit for the fuel pump relay and pump. The fuse is located in the PDC.

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 02 Heater Monitor test is being run. 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 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.

CHARGING SYSTEM INDICATOR LAMP-PCM OUTPUT
OPERATION
The PCM turns the instrument panel Charging System Lamp on.

FUEL PUMP RELAY-PCM OUTPUT
DESCRIPTION
The fuel pump relay is located in the PDC. The inside top of the PDC cover has a label showing relay and fuse location,

OPERATION
The fuel pump relay supplies battery voltage to the fuel pump. A buss bar in the Power Distribution Center (PDC) supplies voltage to the solenoid side and contact side of the relay. The fuel pump relay power circuit contains a 20 amp fuse between the buss bar in the PDC and the relay. The fuse also protects the power circuit for the Automatic Shutdown (ASD) relay. The fuse is located in the PDC. .

The PCM controls the fuel pump 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. When the ignition switch is in the On position, the PCM energizes the fuel pump. If the crankshaft position sensor does not detect engine rotation, the PCM de-energizes the relay after approximately one second.

DUTY CYCLE EVAP PURGE SOLENOID-PCM OUTPUT
DESCRIPTION

Duty Cycle EVAP 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.

OPERATION
The duty cycle EVAP purge solenoid regulates the rate of vapor flow from the EVAP canister to the throttle body. The powertrain control module 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 de-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.

ELECTRIC EGR TRANSDUCER-PCM OUTPUT
DESCRIPTION

Electric EGR Backpressure Transducer-Typical:

The transducer mounts to the clean air hose and the EGR valve mount to the rear of the cylinder head.

OPERATION

Electric EGR Backpressure Transducer-Typical:

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 multi- port fuel injection system. The 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
OPERATION
The PCM regulates the charging system voltage within a range of 12.9 to 15.0 volts.

IDLE AIR CONTROL MOTOR-PCM OUTPUT
DESCRIPTION

Idle Air Control Motor Air Bypass Passage-Typical:

The Idle Air Control (IAC) motor is mounted on the throttle body. The PCM operates the idle air control motor.

OPERATION
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
DESCRIPTION

Data Link Connector:

The data link connector is located inside the vehicle, under the instrument panel, left of the steering column.

OPERATION
The data link connector (diagnostic connector) links the DRB scan tool with the powertrain control module (PCM). Refer to On-Board Diagnostics in the General Diagnosis.

FUEL INJECTORS-PCM OUTPUT
DESCRIPTION

Fuel Injector:

OPERATION
The 2.0L engine uses 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 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. 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
DESCRIPTION

Ignition Coil Pack:

The coil assembly consists of 2 coils molded together. The coil assembly is mounted over the valve cover.

OPERATION
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. Coil number one fires cylinders 1 and 4. Coil number two fires cylinders 2 and 3. The PCM determines which of the coils to charge and fire at the correct time.

The Auto 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 Auto Shutdown (ASD) Relay-PCM Output in for relay operation.

MALFUNCTION INDICATOR (CHECK ENGINE) LAMP-PCM OUTPUT
OPERATION
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.

SOLID STATE FAN RELAY-PCM OUTPUT
DESCRIPTION
The SSFR relay is located on the left front inner frame just behind the radiator.

OPERATION
The radiator fan runs when coolant temperature and A/C system pressure demand cooling. The radiator fan circuit contains a Solid State Fan Relay (SSFR).

A 5 volt signal is supplied to the SSFR. The PCM provides a pulsed ground for the SSFR. Depending upon the amount of pulse on time, the SSFR puts out a proportional voltage to the fan motor at the lower speed. For instance, if the on time is 30 percent, then the voltage to the fan motor will be 3.6 volts.

When engine coolant reaches approximately 99°C (210°F) the PCM grounds the SSFR relay. When the PCM grounds the relay it operates at a 30% duty cycle and immediately ramps up to 100% duty cycle. The PCM de-energizes the SSFR relay when coolant temperature drops to approximately 93°C (199°F).

Also, when the air conditioning pressure switch closes, the PCM grounds the SSFR. The air conditioning switch closes at 285 psi ± 10 psi. When air conditioning pressure drops approximately 40 psi, the pressure switch opens and the fan turns off.

SCI RECEIVE-PCM OUTPUT
OPERATION
SCI Receive is the serial data communication receive circuit for the DRB scan tool. The Powertrain Control Module (PCM) receives data from the DRB through the SCI Receive circuit.

TACHOMETER-PCM OUTPUT
OPERATION
The PCM operates the tachometer on the instrument panel. The PCM calculates engine RPM from the crankshaft position sensor input.

TORQUE CONVERTOR CLUTCH SOLENOID-PCM OUTPUT
OPERATION

Torque Converter Clutch Solenoid:

Three-speed automatic transaxles use a torque converter clutch solenoid. The PCM controls the engagement of the torque converter clutch through the solenoid. The torque converter clutch is engaged up only in direct drive mode.

5 VOLT SUPPLY-PCM OUTPUT
OPERATION
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
OPERATION
The PCM supplies 8 volts to the crankshaft position sensor, camshaft position sensor.