Electric Throttle
The PCM uses the electric throttle to help regulate engine torque.
The electric throttle is located between the charge air cooler connecting pipe and the intake manifold. The electric throttle is secured to the manifold with 4 bolts.
The electric throttle comprises the throttle body and a round throttle butterfly valve. The throttle butterfly valve is actuated by a Direct Current (DC) motor. The electric throttle is controlled by the PCM which receives positional signals from the Throttle Position Sensor (TPS).
If a failure of the motor occurs, the throttle butterfly valve is returned to an emergency position by springs. The throttle butterfly valve remains partially open with limited engine speed available to the driver.
The electric throttle has a 6-pin connector which connect to the PCM .
The 6-pin connector provides the following connections:
- A 12V supply for the DC motor.
- A ground for the DC motor.
- A 5V reference voltage from the PCM .
- TPS negative signal to the PCM .
- TPS positive signal to the PCM .
- A ground connection.
As the throttle angle increases, the output of the negative sensor decreases and the output of the positive sensor increases.
The motor is a DC motor which drives a gear wheel. The motor rotates the spindle to which the throttle butterfly valve is attached. The PCM uses Pulse Width Modulated (PWM) signal to adjust the position of the throttle butterfly valve. The amount of air entering the inlet manifold is regulated by the position of the throttle butterfly valve.
The throttle butterfly valve and the DC motor has 2 maximum positions. The throttle butterfly valve closed which allows minimal air flow through the electric throttle into the intake manifold. The throttle butterfly valve open which allows maximum air flow into the intake manifold.
The PCM calculates the throttle butterfly valve position by comparing the feedback signal from the TPS. The PCM performs a self-test and a calibration routine on the throttle butterfly valve position at each ignition cycle. This is achieved by the PCM powering the DC motor to fully close the throttle butterfly valve and if required, fully open the throttle butterfly valve.
The PCM monitors the DC motor and the TPS for faults and can store fault related DTC . The DTC can be retrieved using a JLR approved diagnostic equipment. In the event of a fault the engine MIL in the Instrument Panel Cluster Control Module (IPC) is also illuminated.