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Potentiometers

Potentiometers


There are three potentiometers in the soft top system. Their task is to supply information to the control module on the exact positions of the soft top, the fifth bow and the soft top cover. This information is necessary for the control module to control the raising and lowering of the soft top.

All three potentiometers work in the same way. They are connected directly to their respective components via levers. When the soft top system is being operated, a slip contact is moved over the carbon ring in the potentiometer, changing its resistance. The control module detects this as a change in voltage on the potentiometer pin 2. By measuring the voltage, the control module can determine the position of the component.

Pin 1 on the potentiometers is supplied with 5V form pin 15 on the control module (K42). Pin 3 on the potentiometers is grounded via pin 29 on the control module (K42). The potentiometer reading is taken on pin 2 and is fed to the control module on the following pins:


• Pin 30 (K42) main motor potentiometers

• Pin 31 (K42) fifth bow potentiometer

• Pin 32 (K42) soft top cover potentiometer


In order to maintain the best possible contact on the connections to the potentiometers, the control module puts 12 V out from pins 15, 30, 31 and 32 (K42) to burn off any deposits on the connections. This is done for 500 ms before the control module goes into a state of rest. Two Zener diodes between connections 1 and 3 and between connections 2 and 3 in each potentiometer ensure that the burn-off functions correctly. The Zener diodes have a Zener voltage of 6.2V. If they are supplied with a higher voltage than 6.2V, their resistance will be very low. When the control module puts out the burn-off voltage of 12V, the Zener diodes short-circuit the voltage to ground. The burn-off current passes directly via the potentiometer connections.

After work has been carried out on the soft top system that has involved removing the control module, a potentiometer or the soft top, the end positions of the potentiometers must be reprogrammed in the control module. This must also be performed after adjusting the soft top or soft top cover.

Main motor potentiometer



The main motor potentiometer is located by the left-hand main motor and detects the position of the soft top.



Fifth bow potentiometer



The fifth bow potentiometer is located by the right-hand fifth bow motor.



Soft top cover potentiometer



The position of the soft top cover is detected by a potentiometer located by the motor that operates the soft top cover.