Chevrolet Spark automatic transmission speed sensor
The speed sensor is an important component in automatic transmissions (AT) of Chevrolet Spark vehicles. It measures the rotational speed of the transmission shaft and transmits this information to the electronic control unit (ECU).
Location and principle of operation
The speed sensor is usually located on the transmission housing. It consists of the following components:
* Magnetic Core: Collects the teeth on the gear attached to the transmission shaft.
* Coil: Creates an electric current when the gear rotates.
* Electrical circuit: Sends current to the ECU.
As the transmission shaft rotates, the gear teeth pass through the sensor’s magnetic core. This leads to the appearance of current pulses in the sensor, the frequency of which is proportional to the rotation speed.
Functions
The speed sensor performs several important functions in an automatic transmission:
* Shift Control: The ECU uses speed data to determine the optimal gear shift point.
* Torque Converter Lockup: The speed sensor also detects the lockup speed of the torque converter to improve efficiency and fuel economy.
* Cruise control control: The speed sensor is used by the cruise control system to maintain a set speed.
* Fault Diagnosis: Speed sensor data can be used to identify potential transmission or engine problems.
Malfunctions and symptoms
A faulty speed sensor can lead to various problems such as:
* Incorrect gear shifting
*Transmission slipping or vibration
* Check Engine Lamp (CEL) comes on
* Increased fuel consumption
Replacement
If the speed sensor is faulty, it must be replaced by a qualified mechanic. Replacement usually involves the following steps:
*Disconnecting the negative battery terminal
* Removing the speed sensor cover
* Disconnecting the electrical connector
* Unscrewing the speed sensor
* Installing a new speed sensor
* Electrical connector connection
* Installing the speed sensor cover
*Connecting the negative terminal of the battery
After replacing the speed sensor, you must reset the adaptive values of the ECU by disconnecting the battery for a few minutes. This will allow the ECU to learn the new speed sensor parameters and ensure optimal transmission operation.