Control System

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/IAT) sensor
- intake air temperature (IAT) sensor
- heated oxygen sensor (HO2S)
- catalyst monitor sensor
- power steering pressure (PSP) switch - 3.0L (4V)
- knock sensor (KS) 2.0L Zetec
- 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/IAT 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/IAT 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 cruise control amplifier to disengage the cruise control system when the clutch pedal is depressed.