Electronic Engine Controls

The electronic engine controls consist of the following:

• Powertrain control module (PCM)
• Throttle position (TP) sensor
• Idle air control (IAC) valve
• Engine coolant temperature (ECT) sensor (3.0L and 4.0L)
• Camshaft position (CMP) sensor
• Crankshaft position (CKP) sensor
• Mass air flow (MAF) sensor
• Manifold absolute pressure (MAP) sensor (2.3L)
• Intake air temperature (IAT) sensor
• Heated oxygen sensor (HO2S)
• Catalyst monitor sensor
• Wheel speed sensor
• Cylinder head temperature (CHT) sensor (2.3L)

The PCM:

• Accepts input from various engine sensors to compute the fuel flow rate necessary to maintain a prescribed air/fuel ratio throughout the entire engine operating range.
• Outputs a command to the fuel injectors to meter the appropriate quantity of fuel.

The TP sensor:

• Sends the PCM a signal indicating the throttle plate angle.
• Is the main input to the PCM from the driver.

The IAC valve:

• Controls bypass air around the throttle plate at low speeds.
• Is controlled by the PCM.

The ECT sensor (3.0L and 4.0L):

• Sends the PCM a signal indicating engine coolant temperature.
• Resistance decreases as coolant temperature increases.

The CHT sensor (2.3L):

• Sends the PCM a signal indicating cylinder head temperature.

The CMP sensor:

• Provides camshaft position information which is used by the PCM for fuel synchronization.

The CKP sensor:

• Sends the PCM a signal indicating crankshaft position.
• Is essential for calculating spark timing.

The MAF sensor:

• Uses a hot wire sensing element to measure the amount of air entering the engine.
• Sends the PCM a signal to determine the intake air mass. The PCM will then calculate the required fuel injector pulse width in order to provide the desired air/fuel ratio.

The MAP sensor:

• Measures manifold vacuum and converts it to an electrical signal. This provides the PCM information on engine load.

The IAT sensor (3.0L and 4.0L):

• Sends the PCM a signal indicating the temperature of the air entering the engine.
• Resistance decreases as temperature increases.

The HO2S:

• Has the ability to create a voltage signal dependent on exhaust oxygen content.
• Provides feedback information to the PCM used to calculate fuel delivery.

The catalyst monitor sensor:

• Has the ability to create a voltage signal dependent on exhaust oxygen content.
• Provides feedback information to the PCM used to calculate fuel delivery.

The wheel speed sensor:

• Sends a signal to the PCM indicating wheel speed.