Automatic transmission solenoids
Automatic transmission (AT) solenoids are electromagnetic devices that control the flow of fluid to change gears. Solenoid resistance can help in diagnosing and identifying automatic transmission faults.
Typical resistance values for automatic transmission solenoids
The resistance of automatic transmission solenoids varies depending on the type of vehicle and automatic transmission model. Below are typical resistance values for some common solenoids:
* Torque converter lock-up solenoid: 11-15 ohms
* Shift Solenoid: 5-10 ohms
* Linear Switching Pressure Solenoid: 10-20 ohms
* Main switch pressure solenoid: 15-25 ohms
Diagnostics by measuring the resistance of solenoids
Measuring the resistance of the solenoids can help determine the following faults:
* Open Circuit: If the resistance is infinite (ohms), this indicates an open circuit in the solenoid or its wiring.
*Short Circuit: If the resistance is close to zero (ohms), it may indicate a short circuit in the solenoid.
* Solenoid wear: Solenoid resistance may deviate from typical values, which may indicate wear or damage to the solenoid.
Steps to measure the resistance of automatic transmission solenoids
To measure the resistance of the automatic transmission solenoids, follow these steps:
1. Find automatic transmission wiring diagrams for your car.
2. Determine the location of the solenoids and their terminals.
3. Disconnect the battery and allow it to drain for your safety.
4. Locate the solenoid terminals.
5. Using a multimeter set to resistance (ohms) mode, connect one probe to one solenoid terminal and the other probe to the other terminal.
6. Record the resistance value.
7. Repeat steps for other solenoids.
Notes:
*Always refer to your vehicle’s wiring diagram for accurate resistance readings.
* Resistance measurements should be carried out on a cold engine.
*If you are unsure about measurements or diagnosis, consult a qualified mechanic.