Safety Warning
DIY auto repair can cause serious injury, fire, or vehicle damage. These guides are for informational purposes only. Always follow OEM torque specs, wear PPE, and consult a certified mechanic if you are unsure. You are solely responsible for your safety.
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.
Use the Manual With the Right Hardware
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When to See a Mechanic
Stop DIY work and contact a certified mechanic immediately if any of the following apply:
- • You smell fuel, burning insulation, or see smoke.
- • Brakes feel soft, pull hard to one side, or make grinding noises.
- • The engine overheats, stalls repeatedly, or misfires under load.
- • You are missing required tools, torque specs, or safe lifting equipment.
- • You are not confident in the next step or safety outcome.
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