Throttle Control

The ECM controls the positioning of the throttle disc in the electric throttle using information from the APP sensor and the TP sensor. Data from the A/C pressure sensor, TCM, ECT sensor, MAF sensor and the MAP/IAT sensor is also used to determine the correct throttle control.

The two Hall effect sensors in the TP sensor are designated 1 and 2. Both sensors output an increasing voltage as the throttle disc angle increases. Small air flows through the throttle require comprehensive regulation, therefore the voltage rise in one of the sensors increases more quickly than the other sensor which gives accurate control of the throttle and ensure the throttle disc is in the correct position.

The ECM monitors the signals from both sensors to ensure they are within the minimum and maximum thresholds and that the signals correspond to the same throttle disc position. If there is a difference in the signals the ECM uses a default throttle signal calculated from the electric throttle load, engine speed and air pressure and temperature signals. The sensor whose output signal is closest to the calculated throttle disc angle will be used as the correct output. A fault code will be recorded for the other sensor and this can be read using a Land Rover approved diagnostic system. The ECM then monitors the remaining sensor output signal and compares it against the calculated value. If a difference in the comparison occurs the ECM will discount the output from both sensors and disable the electric throttle control and revert to a limp home mode. The throttle disc has springs for opening and closing and the ECM can measure the load applied by these springs for a load signal. If a fault occurs which prevents the damper motor from being operated, the springs return the throttle disc to a position which allows a throttle opening large enough to allow the vehicle to driven, but with reduced drive ability.

Throttle Adaptions 

The ECM has a learning adaption which allows the ECM to calculate the precise control required for the electric throttle damper motor. The adaption process is performed when the ignition is on and the engine is not running. The throttle disc is moved by the damper motor to the fully closed position and the ECM records the values output by the TP sensor potentiometers.

If the permanent battery supply to the ECM has been removed, then previous adaptions will have been lost. If adaptions are stored, then the ECM compares the stored adaption values with the current throttle angle and uses an average of the stored and current values to create the new adaption value.

If the electric throttle unit has been replaced, the power supply must be removed from the ECM to erase all previously stored adaption values.