* Transmission Problems: This is the most likely culprit. Issues could include:
* Low or no transmission fluid: Insufficient fluid prevents proper clutch engagement.
* Faulty transmission solenoids or valves: These electrical components control fluid flow within the transmission. A malfunctioning solenoid can prevent gear selection.
* Internal transmission damage: Worn gears, broken clutches, or other internal damage can prevent the transmission from engaging.
* Torque Converter Issues: The torque converter connects the engine to the transmission. Problems with its lockup or internal components can prevent power transfer.
* Engine Problems: Although less likely given the engine is running, problems could include:
* Insufficient engine power: A severely underpowered engine might not be able to overcome internal transmission resistance or other friction. This is usually accompanied by other symptoms.
* Control System Issues:
* Faulty shift selector: The selector itself might be malfunctioning, not properly engaging the transmission.
* Electrical Problems: A wiring fault, a blown fuse, or a problem with the transmission control module (TCM) could prevent the transmission from receiving the correct signals.
* Brake System Issues:
* Parking brake engaged: A simple but important check. Make sure the parking brake is fully released.
* Other Mechanical Issues:
* Driveshaft problems: A broken or disconnected driveshaft would prevent power transfer to the wheels.
Troubleshooting Steps:
1. Check the parking brake: Ensure it's completely disengaged.
2. Check the transmission fluid level: Low fluid is a common cause.
3. Listen for unusual noises: Grinding, whining, or banging sounds from the transmission indicate internal problems.
4. Check the engine RPM: If the engine RPM increases when the accelerator is pressed but the car doesn't move, the problem is likely within the transmission or drivetrain.
5. Have the vehicle professionally diagnosed: A mechanic can use diagnostic tools to pinpoint the exact cause of the problem. This is crucial as internal transmission repairs can be expensive.
Without more specifics about the vehicle, it's impossible to diagnose the problem definitively. A qualified mechanic is needed to accurately assess the situation and perform the necessary repairs.
