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 (4V)
• cylinder head temperature (CHT) sensor-2.0L Zetec
• camshaft position (CMP) sensor
• crankshaft position (CKP) sensor
• mass air flow (MAF) sensor
• intake air temperature (IAT) sensor
• heated oxygen sensor (HO2S)
• catalyst monitor sensor
• power steering pressure (PSP) switch-3.0L (4V)
• knock sensor (KS)
• clutch pedal position (CPP) switch

The PCM needs the following inputs to calibrate the engine correctly:

• crankshaft position
• camshaft position
• engine rpm
• engine load
• engine coolant temperature
• mass air flow
• amount of engine detonation

The TP sensor:

• sends the PCM a signal indicating throttle plate angle.
• is the main input to the PCM from the driver.
• on the 2.0L Zetec is not repaired separately from the throttle body.

The IAC valve:

• controls bypass air around the throttle plate at low speeds.
• is controlled be the PCM.

The ECT sensor:

• sends the PCM a signal indicating engine temperature.
• resistance decreases as coolant temperature increases.

The CHT sensor:

• sends the PCM a signal indicating the cylinder head temperature.
• resistance decreases as coolant temperature increases.

The CMP sensor:

• sends the PCM a signal indicating camshaft position used for fuel synchronization.

The CKP sensor:

• sends the PCM a signal indicating crankshaft position.
• is essential for calculating spark timing.

The MAF sensor:

• sends the PCM a signal indicating mass air flow rate of air entering the engine.

The IAT sensor:

• sends the PCM a signal indicating the temperature of the air entering the engine.
• is incorporated into the MAF sensor and is repaired as an assembly.

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:

• monitors oxygen content after it flows through the catalytic converter.
• provides a voltage to the PCM used to calculate catalytic converter integrity.

The PSP switch:

• sends a signal to the PCM to increase idle speed for engine stability when power steering pump pressure increases above a set pressure value.

The KS:

• sends a signal to the PCM indicating engine detonation, which retards the ignition timing as necessary.

The CPP switch:

• is mounted on the clutch pedal bracket.
• sends a signal to the speed control amplifier to disengage the speed control system when the clutch pedal is depressed.