Automatic transmission shift position sensor
Purpose
The Transmission Range Sensor (TRS) is a device that detects the position of the gear lever in an automatic transmission. It tells the transmission control module (TCM) or engine control unit (ECU) of the selected gear.
Operating principle
A shift position sensor is usually a set of switches or position sensors that are activated when the gear shift lever is in a certain position. It can be located on the gearshift lever or on the transmission itself.
The switches or position sensors are connected to the TCM or ECU via a wiring harness. When the gearshift lever is moved, the position sensor switches the corresponding switches or position sensors. This change in voltage or resistance is detected by the control module and interpreted as a specific gear position.
Types of automatic transmission shift position sensors
There are several types of automatic transmission shift position sensors, including:
* Mechanical switches
*Hall effect position sensors
* Magnetoresistive sensors
Location
The automatic transmission shift position sensor is usually located:
* On the gear lever
* On the gearbox next to the gear lever
* Inside the gearbox itself
Malfunctions
A faulty automatic transmission shift position sensor can lead to the following problems:
* Incorrect display of gear position on the dashboard
* No gear engagement
* Difficulty shifting gears
* Shocks or slipping when shifting gears
*Check engine light
Diagnostics and replacement
You can diagnose a faulty automatic transmission shift position sensor using a fault code scanner. If the sensor is faulty, it must be replaced. Replacing the sensor usually requires removing the shift lever and/or transmission.