56 Ride height control sensor

This type of sensor is used in the Toyota height control system that is reviewed in Chapter 1. Figure 5.19 shows the details of the sensor and it may be seen that it uses the principle of the potential divider that is used in a variety of other vehicle sensor applications.

Vertical movement of the vehicle body, relative to the wheels, is converted to rotary movement of the sensor brush by means of the sensor arm. The voltage detected at the sensor signal terminal is dependent on the position of the brush relative to the two ends of the resistive track. Figure 5.20 shows an oscilloscope trace of the signal that the height sensor sends to the control computer. At point (1), the suspension dampers are fully extended. As the vehicle load is increased, the height decreases and this causes the sensor voltage to fall, as shown at (2) on

Fig. 5.19 A ride height sensor
Fig. 5.20 Typical voltage trace for a ride height sensor

the trace. When the suspension is compressed to the lowest height, the voltage level as indicated at (3), causes the control computer to output a signal to the height control actuator and the vehicle height will be restored to the required level.

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