Which sign may indicate a problem with the transmission solenoid?

A harsh and erratic shifting experience in a vehicle can indeed indicate a problem with the transmission solenoid. The transmission solenoid is responsible for controlling the flow of transmission fluid, which is essential for smooth shifting between gears. When the solenoid malfunctions, it may fail to regulate the hydraulic pressure correctly, resulting in abrupt or rough transitions as the vehicle shifts gears. This can lead to the sensation of jerking or erratic behavior during gear changes, rather than the smooth and gradual shifts that a properly functioning transmission would provide.

The symptoms associated with the other options do not directly relate to the functioning of the transmission solenoid in the same way. Increased fuel consumption could be caused by various factors, including driving habits or engine issues. An unresponsive throttle typically points to problems with the engine management system or throttle control rather than the transmission itself. Overheating in the engine may indicate cooling system issues or engine performance concerns, which again do not directly tie to the function of the transmission solenoid. Therefore, the clear connection between harsh, erratic shifting and the role of the transmission solenoid makes this the correct indicator of potential solenoid problems.