Inputs

Fig. 2 Data Link (Diagnostic) Connector:

DATA LINK CIRCUITS
The Powertrain Control Module (PCM) communicates with the DRB Scan Tool through the data link receive and transmit circuits. Technicians can connect the DRB Scan Tool to the data link connector. The data link connector contains 16 terminals. Terminal 6 is the Data Link Engine Receive circuit. Terminal 7 is the Data Link Engine Transmit (K-Line) circuit.

DATA LINK CONNECTOR
The data link connector ([1][2]diagnostic connector) links the DRB scan tool with the Powertrain Control Module (PCM). Refer to On-Board Diagnostics in Emission Control Systems. The data link connector is located inside the vehicle, under the instrument panel, at the driver's kick panel Fig. 2.

AIR CONDITIONING PRESSURE TRANSDUCER - PCM INPUT
The Powertrain Control Module (PCM) monitors the A/C compressor discharge (high side) pressure through the air conditioning pressure transducer. The transducer supplies an input to the PCM. The PCM engages the A/C compressor clutch if pressure is sufficient for A/C system operation.

ASD SENSE CIRCUIT - PCM INPUT
The Automatic Shutdown (ASD) sense circuit informs the PCM when the ASD relay energizes. When energized, the ASD relay supplies battery voltage to the fuel injectors, ignition coils, and the heating element in each oxygen sensor. If the PCM does not receive 12 volts from this input after grounding the ASD relay, it sets a diagnostic trouble code.

BATTERY VOLTAGE - PCM INPUT
The PCM monitors battery voltage input to determine fuel injector pulse width and generator field control. If battery voltage is low the PCM will increase injector pulse width (period of time that injector is energized).

BATTERY TEMPERATURE SENSOR - PCM INPUT
The PCM uses the temperature of the battery area to control the charge rate. The signal is used to regulate the system voltage. The system voltage is higher at cold temperatures and is gradually reduced as temperature is increased.

BRAKE SWITCH - PCM INPUT
When the brake switch is activated, the PCM receives an input indicating that brakes are being applied. The brake switch is mounted on the brake pedal support bracket.

Fig. 4 Intake Air Temperature Sensor And MAP Sensor:

INTAKE AIR TEMPERATURE SENSOR - PCM INPUT
The Intake Air Temperature (IAT) sensor measures the temperature of the intake air as it enters the engine. The sensor supplies one of the inputs the PCM uses to determine injector pulse width and spark advance. The IAT sensor threads into the intake manifold Figs. 4.

Fig. 7 Camshaft Position Sensor:

CAMSHAFT POSITION SENSOR - PCM IN PUT
The PCM determines fuel injection synchronization and cylinder identification from inputs provided by the camshaft position sensor and crankshaft position sensor. From the two inputs, the PCM determines crankshaft position.

The camshaft position sensor attaches to the rear of the cylinder head Fig. 7. The sensor also acts as a thrust plate to control camshaft end-play.

Fig. 9 Timing Reference Notches:

CRANKSHAFT POSITION SENSOR - PCM INPUT
The PCM determines what cylinder to fire from the crankshaft and camshaft position sensor input. It is also used to synchronize the fuel injectors with their respective cylinders. Refer to Crankshaft Position Sensor for more information.

The second crankshaft counterweight has two sets of four timing reference notches including a 60 degree signature notch Fig. 9. From the crankshaft position sensor input the PCM determines engine speed and crankshaft angle (position).

Fig. 10 Crankshaft Position Sensor:

The crankshaft position sensor mounts to the engine block behind the generator, just above the oil filter Fig. 10.

Fig. 13 Engine Coolant Temperature Sensor:

ENGINE COOLANT TEMPERATURE SENSOR - PCM INPUT
The coolant temperature sensor has one element. The element supplies coolant temperature signal to the PCM. The PCM supplies coolant temperature information on the CCD Bus to the Body Control Module (BCM) for the instrument panel gauge cluster. The PCM determines engine coolant temperature from the coolant temperature sensor.

As coolant temperature varies, the coolant temperature sensor resistance changes resulting in a different current draw from the PCM.

When the engine is cold, the PCM will provide slightly richer air-fuel mixtures and higher idle speeds until normal operating temperatures are reached.

The coolant sensor threads into the rear of the cylinder head Figs. 13. New sensors have sealant applied to the threads.

[1][2]FUEL LEVEL SENSOR - PCM INPUT
The fuel level input comes across the CCD Bus from the Body Control Module. The input is used for the Fuel System and Misfire Monitors. Refer to On-Board Diagnostics. If the fuel level is below approximately 1/16 of a tank the Fuel System and Misfire monitors will be disabled.

IGNITION SENSE - PCM INPUT
The ignition sense input informs the PCM that the ignition switch is in the Start or Run position.

FIG. 15 Knock Sensor:

KNOCK SENSOR - PCM INPUT
The knock sensor threads into the side of the cylinder block in front of the starter Fig. 15. When the knock sensor detects a knock in one of the cylinders, it sends an input signal to the PCM. In response, the PCM retards ignition timing for all cylinders by a scheduled amount.

Knock sensors contain a piezoelectric material which sends an input voltage (signal) to the PCM. As the intensity of the engine knock vibration increases, the knock sensor output voltage also increases.

Fig. 4 Intake Air Temperature Sensor And MAP Sensor:

MANIFOLD ABSOLUTE PRESSURE (MAP) SENSOR - PCM INPUT
The PCM supplies 5 volts direct current to the MAP sensor. The MAP sensor converts intake manifold pressure into voltage. The PCM monitors the MAP sensor output voltage. As vacuum increases, MAP sensor voltage decreases proportionately. Also, as vacuum decreases, MAP sensor voltage increases proportionately.

At key on, before the engine is started, the PCM determines atmospheric air pressure from the MAP sensor voltage. While the engine operates, the PCM determines intake manifold pressure from the MAP sensor voltage. Based on MAP sensor voltage and inputs from other sensors, the PCM adjusts spark advance and the air/fuel mixture.

The MAP sensor mounts to the intake manifold Fig. 4.

Fig. 16 Upstream Heated Oxygen Sensor:

HEATED OXYGEN SENSORS - PCM INPUT
The input from the upstream heated oxygen sensor tells the PCM the oxygen content of the exhaust gas. Based on this input, the PCM fine tunes the air-fuel ratio by adjusting injector pulse width.

The sensor input switches from 0 to 1 volt, depending upon the oxygen content of the exhaust gas in the exhaust manifold. When a large amount of oxygen is present (caused by a lean air-fuel mixture), the sensor produces voltage as low as 0.1 volt. When there is a lesser amount of oxygen present (rich air-fuel mixture) the sensor produces a voltage as high as 1.0 volt. By monitoring the oxygen content and converting it to electrical voltage, the sensor acts as a rich-lean switch.

The heating element in the sensor provides heat to the sensor ceramic element. Heating the sensor allows the system to enter into closed loop operation sooner. Also, it allows the system to remain in closed loop operation during periods of extended idle.

In Closed Loop, the PCM adjusts injector pulse width based on the upstream heated oxygen sensor input along with other inputs. In Open Loop, the PCM adjusts injector pulse width based on preprogrammed (fixed) values and inputs from other sensors.

The upstream oxygen sensor threads into the outlet flange of the exhaust manifold Fig. 16.

Fig. 20 Park/Neutral Switch:

PARK / NEUTRAL POSITION SWITCH - PCM INPUT
The [1][2]park/neutral position switch is located on the automatic transaxle housing Fig. 20. Manual transaxles do not use park/neutral switches. The switch provides an input to the PCM to indicate whether the automatic transaxle is in Park/Neutral, or a drive gear selection. This input is used to determine idle speed (varying with gear selection) and ignition timing advance. The park/neutral input is also used to cancel vehicle speed control. The park/neutral switch is sometimes referred to as the neutral safety switch.

Fig. 21 Power Steering Pressure Switch:

POWER STEERING PRESSURE SWITCH - PCM INPUT
A pressure sensing switch is located on the power steering gear. The switch Fig. 21 provides an input to the PCM during periods of high pump load and low engine RPM; such as during parking maneuvers.

When power steering pump pressure exceeds 4137 kPa (600 psi), the switch is open. The PCM increases idle air flow through the IAC motor to prevent engine stalling. When pump pressure is low, the switch is closed.

SENSOR RETURN - PCM INPUT
The sensor return circuit provides a low electrical noise ground reference for all of the systems sensors. The sensor return circuit connects to internal ground circuits within the powertrain control module.

SPEED CONTROL - PCM INPUT
The speed control system provides 5 voltage levels to the PCM. The voltages correspond to the On/Off, Set, Resume and Cancel.

The speed control On voltage informs the PCM that the speed control system has been activated. The speed control Set voltage informs the PCM that a fixed vehicle speed has been selected. The speed control Resume voltage indicates the previous fixed speed is requested. The speed control Off voltage tells the PCM that the speed control system has been deactivated. The speed control Cancel voltage tells the PCM to deactivate but retain set speed in memory (same as depressing the brake pedal).

Fig. 22 Throttle Position Sensor:

THROTTLE POSITION SENSOR - PCM INPUT
The throttle position sensor mounts to the side of the throttle body Fig. 22.

The Throttle Position Sensor (TPS) connects to the throttle blade shaft. The TPS is a variable resistor that provides the PCM with an input signal (voltage). The signal represents throttle blade position. As the position of the throttle blade changes, the resistance of the TPS changes.

The PCM supplies approximately 5 volts DC to the TPS. The TPS output voltage (input signal to the PCM) represents throttle blade position. The TPS output voltage to the PCM varies from approximately 0.5 volt at minimum throttle opening (idle) to a maximum of 3.7 volts at wide open throttle.

Along with inputs from other sensors, the PCM uses TPS input to determine current engine operating conditions. The PCM also adjusts fuel injector pulse width and ignition timing based on these inputs.

TRANSMISSION CONTROL MODULE - PCM INPUT
The Transmission Control Module (TCM) supplies 3 inputs to the PCM:
- Vehicle Speed (road speed)
- Torque Management
- Gear Position

VEHICLE SPEED
The TCM supplies vehicle speed and distance traveled inputs to the PCM. From these inputs and the throttle position sensor input, the PCM determines when a deceleration condition occurs.

TORQUE MANAGEMENT
The PCM receives a torque management input from the TCM. 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.

Fig. 24 Vehicle Speed Sensor--Manual Transmission:

VEHICLE SPEED SENSOR - PCM INPUT (MANUAL TRANSMISSION)
The vehicle speed sensor is located in the transmission extension housing Fig. 24. The sensor input is used by the PCM to determine vehicle speed and distance traveled, manual transmission only. Refer to Transmission Control Module for automatic transmission.

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)
- Open Throttle IAC position.