Selector lever position sensor, automatic transmission Citroen C4
Location:
* Located on the automatic transmission selector block in the vehicle interior.
Function:
* Determines the position of the automatic transmission selector and transmits information to the electronic control unit (ECU) of the automatic transmission.
Working principle:
* The sensor consists of a potentiometer attached to the selector.
* When the selector position is changed, the potentiometer changes the resistance, which causes the voltage at the sensor output to change.
* The automatic transmission ECU interprets this voltage change to determine the selected gear.
Symptoms of malfunction:
* Incorrect display of the selected gear on the dashboard
* Difficulty shifting gears
* ‘Limp mode’ (emergency mode) automatic transmission
Causes of malfunction:
* Worn or damaged potentiometer
* Oxidation or contamination of contacts
* Mechanical damage to the automatic transmission selector
Diagnostics:
* Visual inspection of the sensor and wiring
* Measuring the resistance of the potentiometer using a multimeter
* Computer diagnostics to read sensor related error codes
Replacement:
* If the sensor is faulty, it must be replaced with a new one.
* Replacement requires removing the automatic transmission selector unit.
* Installation of a new sensor is carried out in reverse order.
Calibration:
After replacing the sensor, it may need to be calibrated to ensure proper operation of the automatic transmission. Calibration is usually performed using dealer diagnostic equipment.