Electric Throttle

WARNING: This page is about a different car, the 2015 Jaguar XF, 2014 Jaguar XF, and 2013 Jaguar XF. However, it is still accessible from the selected car via links, so may be relevant.

The electric throttle is located at the entrance of the intake manifold and is secured to the manifold with four Torx head bolts.

The electric throttle comprises the throttle body, a round throttle disc which is actuated by a motor and a TP (throttle position) sensor. The electric throttle is controlled by the ECM which receives positional signals from the TP sensors. If a failure of the motor occurs, the throttle disc is returned to an emergency position by the springs, the throttle disc remains partially open with limited engine speed available to the driver.

The electric throttle has six wires which are connected to the ECM. Two wires supply 12V current and ground for the DC (direct current) motor. Four more wires GO to the TP sensor. Two wires supply a 5V reference voltage and a ground to two analog, Hall effect sensors. Two further wires provide the TP sensor negative and positive signal feedback to the ECM. 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 damper motor which drives a gear wheel and two springs; one for opening and one for closing. The motor rotates the spindle to which the throttle disc is attached. PWM signals from the ECM control the motor to adjust the position of the throttle disc, regulating the amount of air entering the inlet manifold for combustion. Movement of the motor is achieved by changing the polarity of the power supply to the DC motor, allowing it to be operated in both directions. The throttle disc and the motor has two maximum positions; throttle disc closed which allows minimal air flow through the electric throttle into the intake manifold and throttle disc open which allows maximum air flow into the intake manifold.

The ECM calculates the throttle disc position by comparing the feedback signals to stored values at a known datum position. The two signals are also compared to ensure that they show an accurate throttle disc position. The ECM performs a self-test and a calibration routine on the throttle disc position at each ignition cycle. This is achieved by the ECM powering the damper motor to fully close the throttle disc and, if required, fully open the throttle disc.

The ECM monitors the DC damper motor and the TP sensor for faults and can store fault related DTC 's. These can be retrieved using a Jaguar approved diagnostic system.