An automatic transmission light that comes on can indicate various problems. Below are the most common reasons:
Low transmission fluid level:
*If the fluid level is below the full mark on the dipstick, it may cause overheating and damage to the transmission.
* Check the fluid level and, if necessary, add the fluid recommended for your vehicle.
Dirty transmission fluid:
*Over time, the fluid can become dirty, which can clog filters and reduce transmission performance.
* Replace fluid and filter according to service recommendations.
Faulty fluid sensor:
* A faulty sensor may give a false low fluid level reading even if it is normal.
* Check the sensor and replace it if necessary.
Wiring problems:
* Electrical problems in the wiring harness leading to the transmission can cause the check light to come on.
* Check the wiring harness for damage or faulty connections.
Solenoid problems:
*Solenoids are used to shift gears and malfunctioning solenoids can cause the check light to come on.
* Check the solenoids and replace them if necessary.
Transmission control unit (TCU) problems:
* The TCU is the computer that controls the transmission. Its malfunction can lead to improper operation of the transmission and the check light coming on.
*Check the TCU using a diagnostic scan tool.
Wear of internal components:
*In some cases, an illuminated check light may indicate internal transmission wear, such as worn clutches or hydraulic components.
*This may require a major overhaul or replacement of the transmission.
What to do:
1. Check the fluid level: Check the transmission fluid level on the dipstick and add if necessary.
2. Scan trouble codes: Use a diagnostic scanner to read any stored trouble codes that may indicate a specific problem.
3. Contact a mechanic: If you cannot determine the problem yourself, contact a qualified mechanic for diagnosis and repair.
4. Don’t Ignore the Problem: An illuminated transmission check light is a serious sign that should not be ignored. Continuing to drive a vehicle with this problem may cause further damage.