Can a bad transmission pump keep the motor from turning over?

Yes, a bad transmission pump can prevent the motor from turning over, especially in vehicles with automatic transmissions. If the transmission pump fails, it can lead to insufficient hydraulic pressure, which may cause the transmission to lock up or not engage properly. This can create a situation where the engine cannot rotate freely, making it difficult or impossible to start. However, other issues can also cause the engine not to turn over, so a thorough diagnosis is needed.